What's this an indication of? This cap was original with the'64 radio. Thanks....
(RCA RHC19B)
:Doug, how would you do that? There are 3 lugs on the current one..it's about 2 inches tall...I think you would use 2 that would add close to the values of the one there now...can they be the metal with the blue plastic?
:
:
I have it in a download file...anyway I could send or post it?
I actually found the capacitor at a local warehouse and replaced it but it took away the buzz and only makes a crinkle sound when I turn it off. Thanks for the help.
:The schematic is located at
http://freepdfhosting.com/a2a50fc93b.pdf
Thanks in advance--let me know if any viewing problems
|
RCA RC-1224 Chassis Schematic:  |
::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::The schematic is located at
:http://freepdfhosting.com/a2a50fc93b.pdf
:Thanks in advance--let me know if any viewing problems
:
:
:
: : : :  : : : :Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf I would appreciate any input from all of you... : : : :Sir David . . . . . : : :I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. : : :I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. : : :That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. : : :I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. : : :If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). : : :But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. : : :Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :position or put a cushion in between, if using a metal stool. :Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. : : :The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. : : :The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. : : :A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. : : :The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. : : :It also could cause squeakee-squawkee if not providing adequate bypassing action. : : :Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. : : :If not . . . .we'll think about it some more. : : :Referencing : : : :Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. : : :Thassitt . . . . : : :73's de Edd : : : : :Progress is made by lazy men looking for an easier way to do things. : : : :  : : : |
:
:
:
: : : : RCA RC-1224 Chassis Schematic: : : : : : : : : : : |
:
:
:
:
:
:
:
:
:::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::The schematic is located at
::http://freepdfhosting.com/a2a50fc93b.pdf
::Thanks in advance--let me know if any viewing problems
::
::
:
:
73's de Edd
|
::
::
::
::
::
::
::
::
::
::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf
:I would appreciate any input from all of you...
::
::
::
::Sir David . . . . .
::
::
::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis.
::
::
::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours.
::
::
::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic .
::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema.
::
::
::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose..
::
::
::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set).
::
::
::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips.
::
::
::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting
::position or put a cushion in between, if using a metal stool.
::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term.
::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be.
::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes.
::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before.
::
::
::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up.
::
::
::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing.
::
::
::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors.
::
::
::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages.
::
::
::It also could cause squeakee-squawkee if not providing adequate bypassing action.
::
::
::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'.
::
::
::If not . . . .we'll think about it some more.
::
::
::Referencing :
::
::
::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit.
::
::
::Thassitt . . . .
::
::
::73's de Edd
::
::
::
::
::Progress is made by lazy men looking for an easier way to do things.
::
::
::
::
::
::
::
::
::
::
::
::
::
:: RCA RC-1224 Chassis Schematic:
::
::
::
::
::
::
::
::
::
::
::
::
::
::
::
::
::
::
::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::The schematic is located at
:::http://freepdfhosting.com/a2a50fc93b.pdf
:::Thanks in advance--let me know if any viewing problems
:::
:::
::
::
:
:
:
: : : : : : : :Many Thanks--will check in the morning.... : : : : : :Sanity and insanity overlap a fine gray line... : : : : : : : |
:
:
:
:::
:::
::: ::: ::: ::: ::: ::: ::: :::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf ::I would appreciate any input from all of you... ::: ::: ::: :::Sir David . . . . . ::: ::: :::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. ::: ::: :::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. ::: ::: :::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. ::: ::: :::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. ::: ::: :::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). ::: ::: :::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. ::: ::: :::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :::position or put a cushion in between, if using a metal stool. :::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. ::: ::: :::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. ::: ::: :::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. ::: ::: :::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. ::: ::: :::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. ::: ::: :::It also could cause squeakee-squawkee if not providing adequate bypassing action. ::: ::: :::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. ::: ::: :::If not . . . .we'll think about it some more. ::: ::: :::Referencing : ::: ::: :::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. ::: ::: :::Thassitt . . . . ::: ::: :::73's de Edd ::: ::: ::: ::: :::Progress is made by lazy men looking for an easier way to do things. ::: ::: ::: ::: ::: ::: ::: |
:::
:::
:::
::: ::: ::: ::: RCA RC-1224 Chassis Schematic: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: |
:::
:::
:::
:::
:::
:::
:::
:::
:::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::The schematic is located at
::::http://freepdfhosting.com/a2a50fc93b.pdf
::::Thanks in advance--let me know if any viewing problems
::::
::::
:::
:::
::
::
:
:
::
:: :: :: :: :: :: :: ::Many Thanks--will check in the morning.... : :: :: :: ::Sir David . . . . . :: :: ::Updated with your proper schematic: :: :: :: ::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. :: ::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. :: ::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. :: ::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. ::with C5 doing the volume controls coupling in action. :: :: ::The centrally located C3 is filling in for the AVC section filtering. :: ::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. :: ::Sooooo that is the run down of electrolytics using your proper schematic. :: ::Clean-clean-clean the band switch contacts. :: ::Thassitt . . . :: :: ::73's de Edd :: :: :: :: ::Sanity and insanity overlap a fine gray line... :: :: :: :: :: :: :: |
::
::
::
::::
::::
:::: :::: :::: :::: :::: :::: :::: ::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf :::I would appreciate any input from all of you... :::: :::: :::: ::::Sir David . . . . . :::: :::: ::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. :::: :::: ::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. :::: :::: ::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . ::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. :::: :::: ::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. :::: :::: ::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). :::: :::: ::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. :::: :::: ::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting ::::position or put a cushion in between, if using a metal stool. ::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. ::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. ::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. ::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. :::: :::: ::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. :::: :::: ::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. :::: :::: ::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. :::: :::: ::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. :::: :::: ::::It also could cause squeakee-squawkee if not providing adequate bypassing action. :::: :::: ::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. :::: :::: ::::If not . . . .we'll think about it some more. :::: :::: ::::Referencing : :::: :::: ::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. :::: :::: ::::Thassitt . . . . :::: :::: ::::73's de Edd :::: :::: :::: :::: ::::Progress is made by lazy men looking for an easier way to do things. :::: :::: :::: :::: :::: :::: :::: |
::::
::::
::::
:::: :::: :::: :::: RCA RC-1224 Chassis Schematic: :::: :::: :::: :::: :::: :::: :::: :::: :::: :::: |
::::
::::
::::
::::
::::
::::
::::
::::
::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::The schematic is located at
:::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::Thanks in advance--let me know if any viewing problems
:::::
:::::
::::
::::
:::
:::
::
::
:
:Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::
::: ::: ::: ::: ::: ::: ::: :::Many Thanks--will check in the morning.... :: ::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::: ::: :::Sir David . . . . . ::: ::: :::Updated with your proper schematic: ::: ::: ::: :::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. ::: :::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. ::: :::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. ::: :::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. :::with C5 doing the volume controls coupling in action. ::: ::: :::The centrally located C3 is filling in for the AVC section filtering. ::: :::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. ::: :::Sooooo that is the run down of electrolytics using your proper schematic. ::: :::Clean-clean-clean the band switch contacts. ::: :::Thassitt . . . ::: ::: :::73's de Edd ::: ::: ::: ::: :::Sanity and insanity overlap a fine gray line... ::: ::: ::: ::: ::: ::: ::: |
:::
:::
:::
:::::
:::::
::::: ::::: ::::: ::::: ::::: ::::: ::::: :::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf ::::I would appreciate any input from all of you... ::::: ::::: ::::: :::::Sir David . . . . . ::::: ::::: :::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. ::::: ::::: :::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. ::::: ::::: :::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. ::::: ::::: :::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. ::::: ::::: :::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). ::::: ::::: :::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. ::::: ::::: :::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :::::position or put a cushion in between, if using a metal stool. :::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. ::::: ::::: :::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. ::::: ::::: :::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. ::::: ::::: :::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. ::::: ::::: :::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. ::::: ::::: :::::It also could cause squeakee-squawkee if not providing adequate bypassing action. ::::: ::::: :::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. ::::: ::::: :::::If not . . . .we'll think about it some more. ::::: ::::: :::::Referencing : ::::: ::::: :::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. ::::: ::::: :::::Thassitt . . . . ::::: ::::: :::::73's de Edd ::::: ::::: ::::: ::::: :::::Progress is made by lazy men looking for an easier way to do things. ::::: ::::: ::::: ::::: ::::: ::::: ::::: |
:::::
:::::
:::::
::::: ::::: ::::: ::::: RCA RC-1224 Chassis Schematic: ::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: |
:::::
:::::
:::::
:::::
:::::
:::::
:::::
:::::
:::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::::The schematic is located at
::::::http://freepdfhosting.com/a2a50fc93b.pdf
::::::Thanks in advance--let me know if any viewing problems
::::::
::::::
:::::
:::::
::::
::::
:::
:::
::
::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:
:
I am done bin tellinks you vots . . . . |
::::
::::
::::
::::
::::
::::
::::
::::
::::
::::Many Thanks--will check in the morning....
:::
:::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
::::
::::
::::Sir David . . . . .
::::
::::
::::Updated with your proper schematic:
::::
::::
::::
::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced.
::::
::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2.
::::
::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location.
::::
::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis.
::::with C5 doing the volume controls coupling in action.
::::
::::
::::The centrally located C3 is filling in for the AVC section filtering.
::::
::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect.
::::
::::Sooooo that is the run down of electrolytics using your proper schematic.
::::
::::Clean-clean-clean the band switch contacts.
::::
::::Thassitt . . .
::::
::::
::::73's de Edd
::::
::::
::::
::::
::::Sanity and insanity overlap a fine gray line...
::::
::::
::::
::::
::::
::::
::::
::::
::::
::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf
:::::I would appreciate any input from all of you...
::::::
::::::
::::::
::::::Sir David . . . . .
::::::
::::::
::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis.
::::::
::::::
::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours.
::::::
::::::
::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic .
::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema.
::::::
::::::
::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose..
::::::
::::::
::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set).
::::::
::::::
::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips.
::::::
::::::
::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting
::::::position or put a cushion in between, if using a metal stool.
::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term.
::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be.
::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes.
::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before.
::::::
::::::
::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up.
::::::
::::::
::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing.
::::::
::::::
::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors.
::::::
::::::
::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages.
::::::
::::::
::::::It also could cause squeakee-squawkee if not providing adequate bypassing action.
::::::
::::::
::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'.
::::::
::::::
::::::If not . . . .we'll think about it some more.
::::::
::::::
::::::Referencing :
::::::
::::::
::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit.
::::::
::::::
::::::Thassitt . . . .
::::::
::::::
::::::73's de Edd
::::::
::::::
::::::
::::::
::::::Progress is made by lazy men looking for an easier way to do things.
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
:::::: RCA RC-1224 Chassis Schematic:
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::
::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::::The schematic is located at
:::::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::::Thanks in advance--let me know if any viewing problems
:::::::
:::::::
::::::
::::::
:::::
:::::
::::
::::
:::
:::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
::
::
:
:
:
: : : : : : : : :Checked at 5pm today-- R50 = 11 Om R51 = 161 Om R52 = 62 Om :What say ye? : :Sir David . . . . . : : : :The Q9 is measuring 107 votes off collector & only half the voltage off B & E. : : : : :I am done bin tellinks you vots . . . . : :That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. : : : That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. : : :Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ω's) R51--- (150Ω's) R52--- (56Ω's) . I'm expecting one or some to be HIGH in value. : : :If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. : : :Thassitt . . . . for now . . . standing by . . .from afar . . . . : : :73's de Edd : : : : :It's my cat's world . . . . . I'm just here to open cans... : : : : : : : |
:
:
:
:
:
:::::
:::::
::::: ::::: ::::: ::::: ::::: ::::: ::::: :::::Many Thanks--will check in the morning.... :::: ::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::::: ::::: :::::Sir David . . . . . ::::: ::::: :::::Updated with your proper schematic: ::::: ::::: ::::: :::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. ::::: :::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. ::::: :::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. ::::: :::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. :::::with C5 doing the volume controls coupling in action. ::::: ::::: :::::The centrally located C3 is filling in for the AVC section filtering. ::::: :::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. ::::: :::::Sooooo that is the run down of electrolytics using your proper schematic. ::::: :::::Clean-clean-clean the band switch contacts. ::::: :::::Thassitt . . . ::::: ::::: :::::73's de Edd ::::: ::::: ::::: ::::: :::::Sanity and insanity overlap a fine gray line... ::::: ::::: ::::: ::::: ::::: ::::: ::::: |
:::::
:::::
:::::
:::::::
:::::::
::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: :::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf ::::::I would appreciate any input from all of you... ::::::: ::::::: ::::::: :::::::Sir David . . . . . ::::::: ::::::: :::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. ::::::: ::::::: :::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. ::::::: ::::::: :::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. ::::::: ::::::: :::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. ::::::: ::::::: :::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). ::::::: ::::::: :::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. ::::::: ::::::: :::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :::::::position or put a cushion in between, if using a metal stool. :::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. ::::::: ::::::: :::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. ::::::: ::::::: :::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. ::::::: ::::::: :::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. ::::::: ::::::: :::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. ::::::: ::::::: :::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. ::::::: ::::::: :::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. ::::::: ::::::: :::::::If not . . . .we'll think about it some more. ::::::: ::::::: :::::::Referencing : ::::::: ::::::: :::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. ::::::: ::::::: :::::::Thassitt . . . . ::::::: ::::::: :::::::73's de Edd ::::::: ::::::: ::::::: ::::::: :::::::Progress is made by lazy men looking for an easier way to do things. ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: |
:::::::
:::::::
:::::::
::::::: ::::::: ::::::: ::::::: RCA RC-1224 Chassis Schematic: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: |
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::::::The schematic is located at
::::::::http://freepdfhosting.com/a2a50fc93b.pdf
::::::::Thanks in advance--let me know if any viewing problems
::::::::
::::::::
:::::::
:::::::
::::::
::::::
:::::
:::::
::::
::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::
:::
::
::
:
:
::
:: :: :: :: :: :: :: :: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm ::Checked at 5pm today-- |
::
::
::
::
::
::::::
::::::
:::::: :::::: :::::: :::::: :::::: :::::: :::::: ::::::Many Thanks--will check in the morning.... ::::: :::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::: :::::: ::::::Sir David . . . . . :::::: :::::: ::::::Updated with your proper schematic: :::::: :::::: :::::: ::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. :::::: ::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. :::::: ::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. :::::: ::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. ::::::with C5 doing the volume controls coupling in action. :::::: :::::: ::::::The centrally located C3 is filling in for the AVC section filtering. :::::: ::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. :::::: ::::::Sooooo that is the run down of electrolytics using your proper schematic. :::::: ::::::Clean-clean-clean the band switch contacts. :::::: ::::::Thassitt . . . :::::: :::::: ::::::73's de Edd :::::: :::::: :::::: :::::: ::::::Sanity and insanity overlap a fine gray line... :::::: :::::: :::::: :::::: :::::: :::::: :::::: |
::::::
::::::
::::::
::::::::
::::::::
:::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: ::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf :::::::I would appreciate any input from all of you... :::::::: :::::::: :::::::: ::::::::Sir David . . . . . :::::::: :::::::: ::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. :::::::: :::::::: ::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. :::::::: :::::::: ::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . ::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. :::::::: :::::::: ::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. :::::::: :::::::: ::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). :::::::: :::::::: ::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. :::::::: :::::::: ::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting ::::::::position or put a cushion in between, if using a metal stool. ::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. ::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. ::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. ::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. :::::::: :::::::: ::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. :::::::: :::::::: ::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. :::::::: :::::::: ::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. :::::::: :::::::: ::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. :::::::: :::::::: ::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. :::::::: :::::::: ::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. :::::::: :::::::: ::::::::If not . . . .we'll think about it some more. :::::::: :::::::: ::::::::Referencing : :::::::: :::::::: ::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. :::::::: :::::::: ::::::::Thassitt . . . . :::::::: :::::::: ::::::::73's de Edd :::::::: :::::::: :::::::: :::::::: ::::::::Progress is made by lazy men looking for an easier way to do things. :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: |
::::::::
::::::::
::::::::
:::::::: :::::::: :::::::: :::::::: RCA RC-1224 Chassis Schematic: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: |
::::::::
::::::::
::::::::
::::::::
::::::::
::::::::
::::::::
::::::::
::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::::::The schematic is located at
:::::::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::::::Thanks in advance--let me know if any viewing problems
:::::::::
:::::::::
::::::::
::::::::
:::::::
:::::::
::::::
::::::
:::::
:::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
::::
::::
:::
:::
::
::
:
:
" Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? " "Checked at 5pm today-- " POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm " Now with your : Also you additionally mentioned changing out the Fairchild manufactured SE4002 . . . Q7 and Q8, which I would not be suspect of yet, and with them not still being commonly "shelf stocked" availables. 73's de Edd A Handy . . . . . Cycles to Hertz Reference / Conversion Chart: |
:::
:::
:::
:::
:::
:::
:::
:::
:::
::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm
:
:::Checked at 5pm today--
::R50 = 11 Om R51 = 161 Om R52 = 62 Om
:::What say ye?
:::
:::Sir David . . . . .
:::
:::
:::
:::The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::
:::
:::
:::
:::I am done bin tellinks you vots . . . .
:::
:::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level.
:::
:::
::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground.
:::
:::
:::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value.
:::
:::
:::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm.
:::
:::
:::Thassitt . . . . for now . . . standing by . . .from afar . . . .
:::
:::
:::73's de Edd
:::
:::
:::
:::
:::It's my cat's world . . . . . I'm just here to open cans...
:::
:::
:::
:::
:::
:::
:::
:::
:::
:::
:::
:::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::Many Thanks--will check in the morning....
::::::
::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::::::
:::::::
:::::::Sir David . . . . .
:::::::
:::::::
:::::::Updated with your proper schematic:
:::::::
:::::::
:::::::
:::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced.
:::::::
:::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2.
:::::::
:::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location.
:::::::
:::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis.
:::::::with C5 doing the volume controls coupling in action.
:::::::
:::::::
:::::::The centrally located C3 is filling in for the AVC section filtering.
:::::::
:::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect.
:::::::
:::::::Sooooo that is the run down of electrolytics using your proper schematic.
:::::::
:::::::Clean-clean-clean the band switch contacts.
:::::::
:::::::Thassitt . . .
:::::::
:::::::
:::::::73's de Edd
:::::::
:::::::
:::::::
:::::::
:::::::Sanity and insanity overlap a fine gray line...
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf
::::::::I would appreciate any input from all of you...
:::::::::
:::::::::
:::::::::
:::::::::Sir David . . . . .
:::::::::
:::::::::
:::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis.
:::::::::
:::::::::
:::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours.
:::::::::
:::::::::
:::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic .
:::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema.
:::::::::
:::::::::
:::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose..
:::::::::
:::::::::
:::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set).
:::::::::
:::::::::
:::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips.
:::::::::
:::::::::
:::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting
:::::::::position or put a cushion in between, if using a metal stool.
:::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term.
:::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be.
:::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes.
:::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before.
:::::::::
:::::::::
:::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up.
:::::::::
:::::::::
:::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing.
:::::::::
:::::::::
:::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors.
:::::::::
:::::::::
:::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages.
:::::::::
:::::::::
:::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action.
:::::::::
:::::::::
:::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'.
:::::::::
:::::::::
:::::::::If not . . . .we'll think about it some more.
:::::::::
:::::::::
:::::::::Referencing :
:::::::::
:::::::::
:::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit.
:::::::::
:::::::::
:::::::::Thassitt . . . .
:::::::::
:::::::::
:::::::::73's de Edd
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::Progress is made by lazy men looking for an easier way to do things.
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
::::::::: RCA RC-1224 Chassis Schematic:
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::
:::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::::::::The schematic is located at
::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
::::::::::Thanks in advance--let me know if any viewing problems
::::::::::
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::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
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: : : : : : : : : : : :Sir Dave . . . . . : : : :"Many Thanks--will check in the morning...." : : : :" Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? " : : :The Q9 is measuring 107 votes off collector & only half the voltage off B & E. " : : : :"Checked at 5pm today-- : : :R50 = 11 Ohm R51 = 161 Ohm R52 = 62 Ohm : : :What say ye? " : : : :" POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm " : : : : :Now with your : : : :The Q9 is measuring 107 votes off collector & only half the voltage off B & E. : : :I had interpreted your "voltages on the Q9 C-E . . .particularly the emitter . . . as being about half of that 107 . . . . which would be ~53 volts ". : : :And, if so, that WOULD have watts of power being applied across those three series resistors of the emitter to ground path and the opening up the weakest link of the three. : : :BUT . . . with your values given they are still in adequate tolerance and such a Cat-Ass-Trophy has not occurred. : : :Sooooooo apparently that referencing to a "half" voltage aspect must be referring to THE Sams schematics designated base (7.4 Vdc) and emitter (6.8Vdc)voltages or now being . . . 3.7 and 3.4 volts ). : : :That, along with the HIGHER than normal main B+ being at its 107 level, is telling us that the Q9 AF output transistor is not getting forward biased on enough to be pulling its prescribed ~32 ma of current thru it, thereby pulling down the main B+ to that lower figure. : : : :Also you additionally mentioned changing out the Fairchild manufactured SE4002 . . . Q7 and Q8, which I would not be suspect of yet, and with them not still being commonly "shelf stocked" availables. : : :Apparently your subbing in of some NTE ? ECG ? family of replacement xstrs as a NTE123AP. : : :Now what let's do next: : : :Check the voltages present on all of the C-B-E's of the three audio circuitrys transistors . .Q7-8-9 and log down and pass on to us. : : :Also check the voltages of the Sams BLACK BOX Referenced 1-6 power supply feed test points like your given #1. :I would certainly expect all to be proportionatively higher than specified. : : :Also no problems on the temporarily reversed FM summing and AVC supply electrolytics . .as per their being damaged. : : :Now SHOULD it have been that C5 at the first base of your series cascaded AF transistors, its leakage could have messed up the biasing of those direct DC coupled Q7-8-9 and potentially given us a condition like we are now apparently having. : : : : :Prayers for your wife . . . . . : : : : : : :73's de Edd : : : : :A Handy . . . . . Cycles to Hertz Reference / Conversion Chart: :  : : : : : : :  : : : : : : : |
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:::: :::: :::: :::: :::: :::: :::: :::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm :: ::::Checked at 5pm today-- :::R50 = 11 Om R51 = 161 Om R52 = 62 Om ::::What say ye? :::: ::::Sir David . . . . . :::: :::: :::: ::::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::: :::: :::: :::: ::::I am done bin tellinks you vots . . . . :::: ::::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. :::: :::: :::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. :::: :::: ::::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value. :::: :::: ::::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. :::: :::: ::::Thassitt . . . . for now . . . standing by . . .from afar . . . . :::: :::: ::::73's de Edd :::: :::: :::: :::: ::::It's my cat's world . . . . . I'm just here to open cans... :::: :::: :::: :::: :::: :::: :::: |
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:::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: ::::::::Many Thanks--will check in the morning.... ::::::: :::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::::: :::::::: ::::::::Sir David . . . . . :::::::: :::::::: ::::::::Updated with your proper schematic: :::::::: :::::::: :::::::: ::::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. :::::::: ::::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. :::::::: ::::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. :::::::: ::::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. ::::::::with C5 doing the volume controls coupling in action. :::::::: :::::::: ::::::::The centrally located C3 is filling in for the AVC section filtering. :::::::: ::::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. :::::::: ::::::::Sooooo that is the run down of electrolytics using your proper schematic. :::::::: ::::::::Clean-clean-clean the band switch contacts. :::::::: ::::::::Thassitt . . . :::::::: :::::::: ::::::::73's de Edd :::::::: :::::::: :::::::: :::::::: ::::::::Sanity and insanity overlap a fine gray line... :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: |
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:::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: ::::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf :::::::::I would appreciate any input from all of you... :::::::::: :::::::::: :::::::::: ::::::::::Sir David . . . . . :::::::::: :::::::::: ::::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. :::::::::: :::::::::: ::::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. :::::::::: :::::::::: ::::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . ::::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. :::::::::: :::::::::: ::::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. :::::::::: :::::::::: ::::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). :::::::::: :::::::::: ::::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. :::::::::: :::::::::: ::::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting ::::::::::position or put a cushion in between, if using a metal stool. ::::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. ::::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. ::::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. ::::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. :::::::::: :::::::::: ::::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. :::::::::: :::::::::: ::::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. :::::::::: :::::::::: ::::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. :::::::::: :::::::::: ::::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. :::::::::: :::::::::: ::::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. :::::::::: :::::::::: ::::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. :::::::::: :::::::::: ::::::::::If not . . . .we'll think about it some more. :::::::::: :::::::::: ::::::::::Referencing : :::::::::: :::::::::: ::::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. :::::::::: :::::::::: ::::::::::Thassitt . . . . :::::::::: :::::::::: ::::::::::73's de Edd :::::::::: :::::::::: :::::::::: :::::::::: ::::::::::Progress is made by lazy men looking for an easier way to do things. :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: |
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:::::::::: :::::::::: :::::::::: :::::::::: RCA RC-1224 Chassis Schematic: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: |
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::::::::::
::::::::::
::::::::::
::::::::::
::::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::::::::The schematic is located at
:::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::::::::Thanks in advance--let me know if any viewing problems
:::::::::::
:::::::::::
::::::::::
::::::::::
:::::::::
:::::::::
::::::::
::::::::
:::::::
:::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
::::::
::::::GOOD MORNING...2-24 9:30 am..
I checked those areas with a digital mult set on AC volts...results:
B C E
Q7 .011 .009 .009
Q8 .009 .013 .009
Q9 .009 1.076 .008
Point 1: 1.307 2:.014 3:.009 4:9.07 5:.009 6:.009
Thanks again....
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:: :: :: :: :: :: :: :: :: :: :: ::Sir Dave . . . . . :: :: :: ::"Many Thanks--will check in the morning...." :: :: :: ::" Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? " :: :: ::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. " :: :: :: ::"Checked at 5pm today-- :: :: ::R50 = 11 Ohm R51 = 161 Ohm R52 = 62 Ohm :: :: ::What say ye? " :: :: :: ::" POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm " :: :: :: :: ::Now with your : :: :: ::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :: :: ::I had interpreted your "voltages on the Q9 C-E . . .particularly the emitter . . . as being about half of that 107 . . . . which would be ~53 volts ". :: :: ::And, if so, that WOULD have watts of power being applied across those three series resistors of the emitter to ground path and the opening up the weakest link of the three. :: :: ::BUT . . . with your values given they are still in adequate tolerance and such a Cat-Ass-Trophy has not occurred. :: :: ::Sooooooo apparently that referencing to a "half" voltage aspect must be referring to THE Sams schematics designated base (7.4 Vdc) and emitter (6.8Vdc)voltages or now being . . . 3.7 and 3.4 volts ). :: :: ::That, along with the HIGHER than normal main B+ being at its 107 level, is telling us that the Q9 AF output transistor is not getting forward biased on enough to be pulling its prescribed ~32 ma of current thru it, thereby pulling down the main B+ to that lower figure. :: :: :: ::Also you additionally mentioned changing out the Fairchild manufactured SE4002 . . . Q7 and Q8, which I would not be suspect of yet, and with them not still being commonly "shelf stocked" availables. :: :: ::Apparently your subbing in of some NTE ? ECG ? family of replacement xstrs as a NTE123AP. :: :: ::Now what let's do next: :: :: ::Check the voltages present on all of the C-B-E's of the three audio circuitrys transistors . .Q7-8-9 and log down and pass on to us. :: :: ::Also check the voltages of the Sams BLACK BOX Referenced 1-6 power supply feed test points like your given #1. ::I would certainly expect all to be proportionatively higher than specified. :: :: ::Also no problems on the temporarily reversed FM summing and AVC supply electrolytics . .as per their being damaged. :: :: ::Now SHOULD it have been that C5 at the first base of your series cascaded AF transistors, its leakage could have messed up the biasing of those direct DC coupled Q7-8-9 and potentially given us a condition like we are now apparently having. :: :: :: :: ::Prayers for your wife . . . . . :: :: :: :: :: :: ::73's de Edd :: :: :: :: ::A Handy . . . . . Cycles to Hertz Reference / Conversion Chart: :: :: :: :: :: :: :: :: :: :: :: :: :: :: :: |
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::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm ::: :::::Checked at 5pm today-- ::::R50 = 11 Om R51 = 161 Om R52 = 62 Om :::::What say ye? ::::: :::::Sir David . . . . . ::::: ::::: ::::: :::::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::::: ::::: ::::: ::::: :::::I am done bin tellinks you vots . . . . ::::: :::::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. ::::: ::::: ::::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. ::::: ::::: :::::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value. ::::: ::::: :::::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. ::::: ::::: :::::Thassitt . . . . for now . . . standing by . . .from afar . . . . ::::: ::::: :::::73's de Edd ::::: ::::: ::::: ::::: :::::It's my cat's world . . . . . I'm just here to open cans... ::::: ::::: ::::: ::::: ::::: ::::: ::::: |
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::::::::: ::::::::: ::::::::: ::::::::: ::::::::: ::::::::: ::::::::: :::::::::Many Thanks--will check in the morning.... :::::::: ::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::::::::: ::::::::: :::::::::Sir David . . . . . ::::::::: ::::::::: :::::::::Updated with your proper schematic: ::::::::: ::::::::: ::::::::: :::::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. ::::::::: :::::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. ::::::::: :::::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. ::::::::: :::::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. :::::::::with C5 doing the volume controls coupling in action. ::::::::: ::::::::: :::::::::The centrally located C3 is filling in for the AVC section filtering. ::::::::: :::::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. ::::::::: :::::::::Sooooo that is the run down of electrolytics using your proper schematic. ::::::::: :::::::::Clean-clean-clean the band switch contacts. ::::::::: :::::::::Thassitt . . . ::::::::: ::::::::: :::::::::73's de Edd ::::::::: ::::::::: ::::::::: ::::::::: :::::::::Sanity and insanity overlap a fine gray line... ::::::::: ::::::::: ::::::::: ::::::::: ::::::::: ::::::::: ::::::::: |
:::::::::
:::::::::
:::::::::
:::::::::::
:::::::::::
::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: :::::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf ::::::::::I would appreciate any input from all of you... ::::::::::: ::::::::::: ::::::::::: :::::::::::Sir David . . . . . ::::::::::: ::::::::::: :::::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. ::::::::::: ::::::::::: :::::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. ::::::::::: ::::::::::: :::::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :::::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. ::::::::::: ::::::::::: :::::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. ::::::::::: ::::::::::: :::::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). ::::::::::: ::::::::::: :::::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. ::::::::::: ::::::::::: :::::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :::::::::::position or put a cushion in between, if using a metal stool. :::::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :::::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :::::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :::::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. ::::::::::: ::::::::::: :::::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. ::::::::::: ::::::::::: :::::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. ::::::::::: ::::::::::: :::::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. ::::::::::: ::::::::::: :::::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. ::::::::::: ::::::::::: :::::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. ::::::::::: ::::::::::: :::::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. ::::::::::: ::::::::::: :::::::::::If not . . . .we'll think about it some more. ::::::::::: ::::::::::: :::::::::::Referencing : ::::::::::: ::::::::::: :::::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. ::::::::::: ::::::::::: :::::::::::Thassitt . . . . ::::::::::: ::::::::::: :::::::::::73's de Edd ::::::::::: ::::::::::: ::::::::::: ::::::::::: :::::::::::Progress is made by lazy men looking for an easier way to do things. ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: |
:::::::::::
:::::::::::
:::::::::::
::::::::::: ::::::::::: ::::::::::: ::::::::::: RCA RC-1224 Chassis Schematic: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: |
:::::::::::
:::::::::::
:::::::::::
:::::::::::
:::::::::::
:::::::::::
:::::::::::
:::::::::::
:::::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::::::::::The schematic is located at
::::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
::::::::::::Thanks in advance--let me know if any viewing problems
::::::::::::
::::::::::::
:::::::::::
:::::::::::
::::::::::
::::::::::
:::::::::
:::::::::
::::::::
::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::::::
:::::::GOOD MORNING...2-24 9:30 am..
:I checked those areas with a digital mult set on AC volts...results:
: B C E
:Q7 .011 .009 .009
:Q8 .009 .013 .009
:Q9 .009 1.076 .008
:Point 1: 1.307 2:.014 3:.009 4:9.07 5:.009 6:.009
:Thanks again....
73’s de Edd
:::::::::::
Howdy . . . . . Horn Honker . . . . 2-24 -2012 . . . 2:15 poste meridian..
What we need is those voltages being metered while being in DC mode.
But in referring to the given AC info we can initially see that the power sections ripple content is fine and that #1 ripple has to almost be up to the 5 Vac threshold before starting to perceive of any power supply related hummmmmmmm in the speaker.
The one variant, is that power supply reference point #4 where you designate it as being 9.07 Vac.
Now since its power feed BEFORE it is from #3 and then the feed just AFTER it is #5 and both of them being down in the decades of millivolts, I do think that you did a voltage mis- read or transposed it down in error.
Do it . .to it . . . again . . .with the DC voltage readings this time.
:::
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::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: :::Sir Dave . . . . . ::: ::: ::: :::"Many Thanks--will check in the morning...." ::: ::: ::: :::" Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? " ::: ::: :::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. " ::: ::: ::: :::"Checked at 5pm today-- ::: ::: :::R50 = 11 Ohm R51 = 161 Ohm R52 = 62 Ohm ::: ::: :::What say ye? " ::: ::: ::: :::" POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm " ::: ::: ::: ::: :::Now with your : ::: ::: :::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::: ::: :::I had interpreted your "voltages on the Q9 C-E . . .particularly the emitter . . . as being about half of that 107 . . . . which would be ~53 volts ". ::: ::: :::And, if so, that WOULD have watts of power being applied across those three series resistors of the emitter to ground path and the opening up the weakest link of the three. ::: ::: :::BUT . . . with your values given they are still in adequate tolerance and such a Cat-Ass-Trophy has not occurred. ::: ::: :::Sooooooo apparently that referencing to a "half" voltage aspect must be referring to THE Sams schematics designated base (7.4 Vdc) and emitter (6.8Vdc)voltages or now being . . . 3.7 and 3.4 volts ). ::: ::: :::That, along with the HIGHER than normal main B+ being at its 107 level, is telling us that the Q9 AF output transistor is not getting forward biased on enough to be pulling its prescribed ~32 ma of current thru it, thereby pulling down the main B+ to that lower figure. ::: ::: ::: :::Also you additionally mentioned changing out the Fairchild manufactured SE4002 . . . Q7 and Q8, which I would not be suspect of yet, and with them not still being commonly "shelf stocked" availables. ::: ::: :::Apparently your subbing in of some NTE ? ECG ? family of replacement xstrs as a NTE123AP. ::: ::: :::Now what let's do next: ::: ::: :::Check the voltages present on all of the C-B-E's of the three audio circuitrys transistors . .Q7-8-9 and log down and pass on to us. ::: ::: :::Also check the voltages of the Sams BLACK BOX Referenced 1-6 power supply feed test points like your given #1. :::I would certainly expect all to be proportionatively higher than specified. ::: ::: :::Also no problems on the temporarily reversed FM summing and AVC supply electrolytics . .as per their being damaged. ::: ::: :::Now SHOULD it have been that C5 at the first base of your series cascaded AF transistors, its leakage could have messed up the biasing of those direct DC coupled Q7-8-9 and potentially given us a condition like we are now apparently having. ::: ::: ::: ::: :::Prayers for your wife . . . . . ::: ::: ::: ::: ::: ::: :::73's de Edd ::: ::: ::: ::: :::A Handy . . . . . Cycles to Hertz Reference / Conversion Chart: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: ::: |
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::::::
::::::
:::::: :::::: :::::: :::::: :::::: :::::: :::::: :::::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm :::: ::::::Checked at 5pm today-- :::::R50 = 11 Om R51 = 161 Om R52 = 62 Om ::::::What say ye? :::::: ::::::Sir David . . . . . :::::: :::::: :::::: ::::::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::: :::::: :::::: :::::: ::::::I am done bin tellinks you vots . . . . :::::: ::::::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. :::::: :::::: :::::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. :::::: :::::: ::::::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value. :::::: :::::: ::::::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. :::::: :::::: ::::::Thassitt . . . . for now . . . standing by . . .from afar . . . . :::::: :::::: ::::::73's de Edd :::::: :::::: :::::: :::::: ::::::It's my cat's world . . . . . I'm just here to open cans... :::::: :::::: :::::: :::::: :::::: :::::: :::::: |
::::::
::::::
::::::
::::::
::::::
::::::::::
::::::::::
:::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: ::::::::::Many Thanks--will check in the morning.... ::::::::: :::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::::::: :::::::::: ::::::::::Sir David . . . . . :::::::::: :::::::::: ::::::::::Updated with your proper schematic: :::::::::: :::::::::: :::::::::: ::::::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. :::::::::: ::::::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. :::::::::: ::::::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. :::::::::: ::::::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. ::::::::::with C5 doing the volume controls coupling in action. :::::::::: :::::::::: ::::::::::The centrally located C3 is filling in for the AVC section filtering. :::::::::: ::::::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. :::::::::: ::::::::::Sooooo that is the run down of electrolytics using your proper schematic. :::::::::: ::::::::::Clean-clean-clean the band switch contacts. :::::::::: ::::::::::Thassitt . . . :::::::::: :::::::::: ::::::::::73's de Edd :::::::::: :::::::::: :::::::::: :::::::::: ::::::::::Sanity and insanity overlap a fine gray line... :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: :::::::::: |
::::::::::
::::::::::
::::::::::
::::::::::::
::::::::::::
:::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: ::::::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf :::::::::::I would appreciate any input from all of you... :::::::::::: :::::::::::: :::::::::::: ::::::::::::Sir David . . . . . :::::::::::: :::::::::::: ::::::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. :::::::::::: :::::::::::: ::::::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. :::::::::::: :::::::::::: ::::::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . ::::::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. :::::::::::: :::::::::::: ::::::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. :::::::::::: :::::::::::: ::::::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). :::::::::::: :::::::::::: ::::::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. :::::::::::: :::::::::::: ::::::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting ::::::::::::position or put a cushion in between, if using a metal stool. ::::::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. ::::::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. ::::::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. ::::::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. :::::::::::: :::::::::::: ::::::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. :::::::::::: :::::::::::: ::::::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. :::::::::::: :::::::::::: ::::::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. :::::::::::: :::::::::::: ::::::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. :::::::::::: :::::::::::: ::::::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. :::::::::::: :::::::::::: ::::::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. :::::::::::: :::::::::::: ::::::::::::If not . . . .we'll think about it some more. :::::::::::: :::::::::::: ::::::::::::Referencing : :::::::::::: :::::::::::: ::::::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. :::::::::::: :::::::::::: ::::::::::::Thassitt . . . . :::::::::::: :::::::::::: ::::::::::::73's de Edd :::::::::::: :::::::::::: :::::::::::: :::::::::::: ::::::::::::Progress is made by lazy men looking for an easier way to do things. :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: |
::::::::::::
::::::::::::
::::::::::::
:::::::::::: :::::::::::: :::::::::::: :::::::::::: RCA RC-1224 Chassis Schematic: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: |
::::::::::::
::::::::::::
::::::::::::
::::::::::::
::::::::::::
::::::::::::
::::::::::::
::::::::::::
::::::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::::::::::The schematic is located at
:::::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::::::::::Thanks in advance--let me know if any viewing problems
:::::::::::::
:::::::::::::
::::::::::::
::::::::::::
:::::::::::
:::::::::::
::::::::::
::::::::::
:::::::::
:::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
::::::::
::::::::GOOD MORNING...2-24 9:30 am..
::I checked those areas with a digital mult set on AC volts...results:
:: B C E
::Q7 .011 .009 .009
::Q8 .009 .013 .009
::Q9 .009 1.076 .008
::Point 1: 1.307 2:.014 3:.009 4:9.07 5:.009 6:.009
::Thanks again....
:
:
::::::::::::
:
:
: Howdy . . . . . Horn Honker . . . . 2-24 -2012 . . . 2:15 poste meridian..
:What we need is those voltages being metered while being in DC mode.
:
:
:But in referring to the given AC info we can initially see that the power sections ripple content is fine and that #1 ripple has to almost be up to the 5 Vac threshold before starting to perceive of any power supply related hummmmmmmm in the speaker.
:
:
:The one variant, is that power supply reference point #4 where you designate it as being 9.07 Vac.
:
:
:Now since its power feed BEFORE it is from #3 and then the feed just AFTER it is #5 and both of them being down in the decades of millivolts, I do think that you did a voltage mis- read or transposed it down in error.
:
:
:Do it . .to it . . . again . . .with the DC voltage readings this time.
:
:
:
:73’s de Edd
:
HOW DUMB AM I? 4:35 2-24
B C E
Q7 3.0 10.77 2.35
Q8 10.80 18.9 10.18
Q9 10.18 70.2 9.58
1: 84 2: 18.8 3: 11.48 4: 10.59 5: 9.97 6: 9.33
Again, thanks..sorry 'bout the screw up.
:
:
:
::::
::::
:::: :::: :::: :::: :::: :::: :::: :::: ::::: :Do it . .to it . . . again . . .with the DC voltage readings this time. : : : :73’s de Edd : HOW DUMB AM I? 4:35 2-24 B C E Q7 3.0 10.77 2.35 Q8 10.80 18.9 10.18 Q9 10.18 70.2 9.58 1: 84 2: 18.8 3: 11.48 4: 10.59 5: 9.97 6: 9.33 |
::::
::::
::::
:::::::
:::::::
::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm ::::: :::::::Checked at 5pm today-- ::::::R50 = 11 Om R51 = 161 Om R52 = 62 Om :::::::What say ye? ::::::: :::::::Sir David . . . . . ::::::: ::::::: ::::::: :::::::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::::::: ::::::: ::::::: ::::::: :::::::I am done bin tellinks you vots . . . . ::::::: :::::::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. ::::::: ::::::: ::::::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. ::::::: ::::::: :::::::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value. ::::::: ::::::: :::::::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. ::::::: ::::::: :::::::Thassitt . . . . for now . . . standing by . . .from afar . . . . ::::::: ::::::: :::::::73's de Edd ::::::: ::::::: ::::::: ::::::: :::::::It's my cat's world . . . . . I'm just here to open cans... ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: |
:::::::
:::::::
:::::::
:::::::
:::::::
:::::::::::
:::::::::::
::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: :::::::::::Many Thanks--will check in the morning.... :::::::::: ::::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. ::::::::::: ::::::::::: :::::::::::Sir David . . . . . ::::::::::: ::::::::::: :::::::::::Updated with your proper schematic: ::::::::::: ::::::::::: ::::::::::: :::::::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. ::::::::::: :::::::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. ::::::::::: :::::::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. ::::::::::: :::::::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. :::::::::::with C5 doing the volume controls coupling in action. ::::::::::: ::::::::::: :::::::::::The centrally located C3 is filling in for the AVC section filtering. ::::::::::: :::::::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. ::::::::::: :::::::::::Sooooo that is the run down of electrolytics using your proper schematic. ::::::::::: :::::::::::Clean-clean-clean the band switch contacts. ::::::::::: :::::::::::Thassitt . . . ::::::::::: ::::::::::: :::::::::::73's de Edd ::::::::::: ::::::::::: ::::::::::: ::::::::::: :::::::::::Sanity and insanity overlap a fine gray line... ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: ::::::::::: |
:::::::::::
:::::::::::
:::::::::::
:::::::::::::
:::::::::::::
::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: :::::::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf ::::::::::::I would appreciate any input from all of you... ::::::::::::: ::::::::::::: ::::::::::::: :::::::::::::Sir David . . . . . ::::::::::::: ::::::::::::: :::::::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. ::::::::::::: ::::::::::::: :::::::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. ::::::::::::: ::::::::::::: :::::::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . :::::::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. ::::::::::::: ::::::::::::: :::::::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. ::::::::::::: ::::::::::::: :::::::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). ::::::::::::: ::::::::::::: :::::::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. ::::::::::::: ::::::::::::: :::::::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting :::::::::::::position or put a cushion in between, if using a metal stool. :::::::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. :::::::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. :::::::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. :::::::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. ::::::::::::: ::::::::::::: :::::::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. ::::::::::::: ::::::::::::: :::::::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. ::::::::::::: ::::::::::::: :::::::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. ::::::::::::: ::::::::::::: :::::::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. ::::::::::::: ::::::::::::: :::::::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. ::::::::::::: ::::::::::::: :::::::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. ::::::::::::: ::::::::::::: :::::::::::::If not . . . .we'll think about it some more. ::::::::::::: ::::::::::::: :::::::::::::Referencing : ::::::::::::: ::::::::::::: :::::::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. ::::::::::::: ::::::::::::: :::::::::::::Thassitt . . . . ::::::::::::: ::::::::::::: :::::::::::::73's de Edd ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: :::::::::::::Progress is made by lazy men looking for an easier way to do things. ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: |
:::::::::::::
:::::::::::::
:::::::::::::
::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: RCA RC-1224 Chassis Schematic: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: ::::::::::::: |
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::
:::::::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
:::::::::::::::The schematic is located at
::::::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
::::::::::::::Thanks in advance--let me know if any viewing problems
::::::::::::::
::::::::::::::
:::::::::::::
:::::::::::::
::::::::::::
::::::::::::
:::::::::::
:::::::::::
::::::::::
::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
:::::::::
:::::::::GOOD MORNING...2-24 9:30 am..
:::I checked those areas with a digital mult set on AC volts...results:
::: B C E
:::Q7 .011 .009 .009
:::Q8 .009 .013 .009
:::Q9 .009 1.076 .008
:::Point 1: 1.307 2:.014 3:.009 4:9.07 5:.009 6:.009
:::Thanks again....
::
::
:::::::::::::
::
::
:: Howdy . . . . . Horn Honker . . . . 2-24 -2012 . . . 2:15 poste meridian..
::What we need is those voltages being metered while being in DC mode.
::
::
::But in referring to the given AC info we can initially see that the power sections ripple content is fine and that #1 ripple has to almost be up to the 5 Vac threshold before starting to perceive of any power supply related hummmmmmmm in the speaker.
::
::
::The one variant, is that power supply reference point #4 where you designate it as being 9.07 Vac.
::
::
::Now since its power feed BEFORE it is from #3 and then the feed just AFTER it is #5 and both of them being down in the decades of millivolts, I do think that you did a voltage mis- read or transposed it down in error.
::
::
::Do it . .to it . . . again . . .with the DC voltage readings this time.
::
::
::
::73’s de Edd
::
:HOW DUMB AM I? 4:35 2-24
: B C E
:Q7 3.0 10.77 2.35
:Q8 10.80 18.9 10.18
:Q9 10.18 70.2 9.58
:
:1: 84 2: 18.8 3: 11.48 4: 10.59 5: 9.97 6: 9.33
:Again, thanks..sorry 'bout the screw up.
::
::
::
:
:
:::::
:::::
::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: :::::: ::Do it . .to it . . . again . . .with the DC voltage readings this time. :: :: :: ::73’s de Edd :: :HOW DUMB AM I? 4:35 2-24 :B C E :Q7 3.0 10.77 2.35 :Q8 10.80 18.9 10.18 :Q9 10.18 70.2 9.58 : :1: 84 2: 18.8 3: 11.48 4: 10.59 5: 9.97 6: 9.33 :Again, thanks..sorry 'bout the screw up. ::::: ::::: :::::Sir Dave . . . . . ::::: ::::: ::::: :::::"Many Thanks--will check in the morning...." ::::: how confusing to follow :::::" Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? " |
:::::
:::::
:::::
::::::::
::::::::
:::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: POINT 1 on the schematic & in that circuit measures 132 votes instead of called for 82.....5:15 pm :::::: ::::::::Checked at 5pm today-- :::::::R50 = 11 Om R51 = 161 Om R52 = 62 Om ::::::::What say ye? :::::::: ::::::::Sir David . . . . . :::::::: :::::::: :::::::: ::::::::The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::::: :::::::: :::::::: :::::::: ::::::::I am done bin tellinks you vots . . . . :::::::: ::::::::That high of a voltage on the collector is telling us that the Q9 is NOT conducting and pulling its specified / designed current level, in order to then be loading down and pulling the collector B+ level on down to its proper level. :::::::: :::::::: :::::::: That is dependent on that transistor being + biased on enough to get current thru it and on down thru the three resistors that eventually connect to ground. :::::::: :::::::: ::::::::Take a cold set ohmmic evaluation of the resistive values of R50--- (10Ù's) R51--- (150Ù's) R52--- (56Ù's) . I'm expecting one or some to be HIGH in value. :::::::: :::::::: ::::::::If some are burnt . . . .we just might possibly have us a leaky Q9, but that is NOT being the norm. :::::::: :::::::: ::::::::Thassitt . . . . for now . . . standing by . . .from afar . . . . :::::::: :::::::: ::::::::73's de Edd :::::::: :::::::: :::::::: :::::::: ::::::::It's my cat's world . . . . . I'm just here to open cans... :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: :::::::: |
::::::::
::::::::
::::::::
::::::::
::::::::
::::::::::::
::::::::::::
:::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: ::::::::::::Many Thanks--will check in the morning.... ::::::::::: :::::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E. :::::::::::: :::::::::::: ::::::::::::Sir David . . . . . :::::::::::: :::::::::::: ::::::::::::Updated with your proper schematic: :::::::::::: :::::::::::: :::::::::::: ::::::::::::I just now see that you have sneaked in its schematic . . . some what different in its being Am-Fm and a dropping of the HIGH voltage drastically on down, just after the C1 electrolytic already replaced. :::::::::::: ::::::::::::Now change my prior numbering references and concentrate on the next . . .MUCH lower voltage rated filter of C2. :::::::::::: ::::::::::::The we have the C6 emitter bypassing filter associated with the Q9 output transistor just above the power supply location. :::::::::::: ::::::::::::Note that we have two pre amp transistors Q7-Q8 before the Q9 as compared to my "guesstimated " chassis. ::::::::::::with C5 doing the volume controls coupling in action. :::::::::::: :::::::::::: ::::::::::::The centrally located C3 is filling in for the AVC section filtering. :::::::::::: ::::::::::::If you have weak-bad, or no FM . . . . then C4 at the top right of the schematic is the suspect. :::::::::::: ::::::::::::Sooooo that is the run down of electrolytics using your proper schematic. :::::::::::: ::::::::::::Clean-clean-clean the band switch contacts. :::::::::::: ::::::::::::Thassitt . . . :::::::::::: :::::::::::: ::::::::::::73's de Edd :::::::::::: :::::::::::: :::::::::::: :::::::::::: ::::::::::::Sanity and insanity overlap a fine gray line... :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: :::::::::::: |
::::::::::::
::::::::::::
::::::::::::
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:::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: ::::::::::::::Many thanks...the actual schematic is located at: :http://freepdfhosting.com/a2a50fc93b.pdf :::::::::::::I would appreciate any input from all of you... :::::::::::::: :::::::::::::: :::::::::::::: ::::::::::::::Sir David . . . . . :::::::::::::: :::::::::::::: ::::::::::::::I don't have access to my vast archived materiel at this site , but with what few bits that you have done tole' us, I think that we can possibly work / compare with the year or so earier RC-1224 chassis. :::::::::::::: :::::::::::::: ::::::::::::::I have marked up a schematic of it and placed the items of most interest to loacting the remaining fallacies with that unit of yours. :::::::::::::: :::::::::::::: ::::::::::::::That mentioned . . . . reduced . . .HIGH voltage that you gave is telling me that the set is a hybrid design of set and using newer NPN planar transistors in the two AF transistors in the top right corner of the schematic . ::::::::::::::And then they are using conventional "old school" design of PNP transistors at their lower operating voltages for the string of the four 38xxx series of RF transistors to the left of the schema. :::::::::::::: :::::::::::::: ::::::::::::::I would guess that your replacement of the dual section cardboard electrolytic, with its tri terminal PCB mounting terminals has got the MAIN B+ back to normal and the HUMMMMMMMMM has abated . . .somewhat fiercely ! . . . . I might suppose.. :::::::::::::: :::::::::::::: ::::::::::::::If you would now fire up the set and locate the volume control for access to it . . . . and it looks like your unit might have placed it a bit away from the PCB proper and on a panel, (as being compared to this 1224 set). :::::::::::::: :::::::::::::: ::::::::::::::But, do run the volume up to MAX and then touch the center terminal of that vol control with the metal of a small standard screwdriver /or/ house- door- car key, of which you are touching its metal, with spittle moistened fingertips. :::::::::::::: :::::::::::::: ::::::::::::::Be insulated from ground with none of your body touching anything , except possibly a wooden stool if in sitting ::::::::::::::position or put a cushion in between, if using a metal stool. ::::::::::::::Now, in that manner , your body should then be picking up some healthy AC house wiring "hummmm" and by your then touching that terminal, it should amplify it , with the use of those last two audio power amp stages and give you a milder version of your previous HUMMMMM . . .when touching the center vol control term. ::::::::::::::If this occors, your "radiator" is operating normal thru the last two audio stages, and we can then further peruse the front of the set, where I suspicion the remaining problems to be. ::::::::::::::I have marked up the other SUSPECT . . . .dried out electrolytic capacitors . . . in "yaller" boxes. ::::::::::::::The very top C19 is suspect for progressively weak audio or none coming in while doing that initial test before. :::::::::::::: :::::::::::::: ::::::::::::::The right side C27 emitter bypass cap would be responsible for considerable loss of audio level if opened up. :::::::::::::: :::::::::::::: ::::::::::::::The intermediately located C28 and C23 are associated with the reduced voltage power supply of the 1st AF amp transistor and its emitter bypassing. :::::::::::::: :::::::::::::: ::::::::::::::A very critical C123, down at the bottom is as an important counterpart of your other filter, which you have already replaced> It is responsible for cleaning up the power filtering of the negative voltage source which supplies your 4 frontal RF transistors. :::::::::::::: :::::::::::::: ::::::::::::::The last C16 . . . me too . . . ME TOO ! . . . is responsible for the filtering your Automatic Volume Control . . . gain aspect of the RF stages. :::::::::::::: :::::::::::::: ::::::::::::::It also could cause squeakee-squawkee if not providing adequate bypassing action. :::::::::::::: :::::::::::::: ::::::::::::::Change those out . . . . and MUCH easier to be able to FIND a supplier of . . . and I think that your 'ole radiator, might be radiating agin'. :::::::::::::: :::::::::::::: ::::::::::::::If not . . . .we'll think about it some more. :::::::::::::: :::::::::::::: ::::::::::::::Referencing : :::::::::::::: :::::::::::::: ::::::::::::::Markee-markee up schematic of OLDER RC -1224 chassis placed below, to compare against your sets bit newer 1228 unit. :::::::::::::: :::::::::::::: ::::::::::::::Thassitt . . . . :::::::::::::: :::::::::::::: ::::::::::::::73's de Edd :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: ::::::::::::::Progress is made by lazy men looking for an easier way to do things. :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: |
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:::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: RCA RC-1224 Chassis Schematic: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: :::::::::::::: |
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::::::::::::::::You can post it on one of the freebie image hosting sites, e.g., Image Shack, and then post the link here.
::::::::::::::::The schematic is located at
:::::::::::::::http://freepdfhosting.com/a2a50fc93b.pdf
:::::::::::::::Thanks in advance--let me know if any viewing problems
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:::::::::::Replaced all elec. capacitors and Q7-Q8. No sound except slight sound on FM/AM when first turned on...no reception--I am lost...any ideas? The Q9 is measuring 107 votes off collector & only half the voltage off B & E.
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::::::::::GOOD MORNING...2-24 9:30 am..
::::I checked those areas with a digital mult set on AC volts...results:
:::: B C E
::::Q7 .011 .009 .009
::::Q8 .009 .013 .009
::::Q9 .009 1.076 .008
::::Point 1: 1.307 2:.014 3:.009 4:9.07 5:.009 6:.009
::::Thanks again....
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::: Howdy . . . . . Horn Honker . . . . 2-24 -2012 . . . 2:15 poste meridian..
:::What we need is those voltages being metered while being in DC mode.
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:::But in referring to the given AC info we can initially see that the power sections ripple content is fine and that #1 ripple has to almost be up to the 5 Vac threshold before starting to perceive of any power supply related hummmmmmmm in the speaker.
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:::The one variant, is that power supply reference point #4 where you designate it as being 9.07 Vac.
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:::Now since its power feed BEFORE it is from #3 and then the feed just AFTER it is #5 and both of them being down in the decades of millivolts, I do think that you did a voltage mis- read or transposed it down in error.
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:::Do it . .to it . . . again . . .with the DC voltage readings this time.
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:::73’s de Edd
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::HOW DUMB AM I? 4:35 2-24
:: B C E
::Q7 3.0 10.77 2.35
::Q8 10.80 18.9 10.18
::Q9 10.18 70.2 9.58
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::1: 84 2: 18.8 3: 11.48 4: 10.59 5: 9.97 6: 9.33
::Again, thanks..sorry 'bout the screw up.
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