The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
Are all tubes lit?
Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
If you're getting static, I would guess that the rectifier and xfmr are working.
Doug
:I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:
:The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:
:Are all tubes lit?
:
:Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:
:If you're getting static, I would guess that the rectifier and xfmr are working.
:Doug
:
::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
Lewis
:
:The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:
:Are all tubes lit?
:
:Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:
:If you're getting static, I would guess that the rectifier and xfmr are working.
:Doug
:
::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
Lewis
*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
Lewis
::
::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
::
::Are all tubes lit?
:
:
:
::
::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
::
::If you're getting static, I would guess that the rectifier and xfmr are working.
::Doug
::
:::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:
:
:Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
:Lewis
:*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
:Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
:Lewis
:::
:::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:::
:::Are all tubes lit?
::
::
::
:::
:::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:::
:::If you're getting static, I would guess that the rectifier and xfmr are working.
:::Doug
:::
::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
::
::
::Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
::Lewis
::*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
::Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
::Lewis
Lewis, Thank you for the reply. I did get a working radio, and set to @1100kHz, and rocked the Zenith dial.I did get the oscillator sound-on the good one- I am assuming that is what was to happen. I get no volume at all. As I turn the volume control, the static stays the same. Thank you, Tim
::::
::::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
::::
::::Are all tubes lit?
:::
:::
:::
::::
::::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
::::
::::If you're getting static, I would guess that the rectifier and xfmr are working.
::::Doug
::::
:::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:::
:::
:::Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
:::Lewis
:::*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
:::Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
:::Lewis
:Lewis, Thank you for the reply. I did get a working radio, and set to @1100kHz, and rocked the Zenith dial.I did get the oscillator sound-on the good one- I am assuming that is what was to happen. I get no volume at all. As I turn the volume control, the static stays the same. Thank you, Tim
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Oh, GOOD,GOOD! We have eliminated the most complicated part of the radio, and pretty much the power supply. We are now down to the IF and audio stages. What happens if you touch the first audio grid (accessable through the TV position of the Radio RV switch)? Do you get a hum or not??
Lewis
:::::
:::::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:::::
:::::Are all tubes lit?
::::
::::
::::
:::::
:::::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:::::
:::::If you're getting static, I would guess that the rectifier and xfmr are working.
:::::Doug
:::::
::::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
::::
::::
::::Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
::::Lewis
::::*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
::::Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
::::Lewis
::Lewis, Thank you for the reply. I did get a working radio, and set to @1100kHz, and rocked the Zenith dial.I did get the oscillator sound-on the good one- I am assuming that is what was to happen. I get no volume at all. As I turn the volume control, the static stays the same. Thank you, Tim
:
:
:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:
:Oh, GOOD,GOOD! We have eliminated the most complicated part of the radio, and pretty much the power supply. We are now down to the IF and audio stages. What happens if you touch the first audio grid (accessable through the TV position of the Radio RV switch)? Do you get a hum or not??
:
:Lewis
Hello Lewis. I,m not sure where you want me to touch to check for the hum.Please let me know. Thank you, Tim.
::::::
::::::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
::::::
::::::Are all tubes lit?
:::::
:::::
:::::
::::::
::::::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
::::::
::::::If you're getting static, I would guess that the rectifier and xfmr are working.
::::::Doug
::::::
:::::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:::::
:::::
:::::Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
:::::Lewis
:::::*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
:::::Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
:::::Lewis
:::Lewis, Thank you for the reply. I did get a working radio, and set to @1100kHz, and rocked the Zenith dial.I did get the oscillator sound-on the good one- I am assuming that is what was to happen. I get no volume at all. As I turn the volume control, the static stays the same. Thank you, Tim
::
::
::~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
::
::Oh, GOOD,GOOD! We have eliminated the most complicated part of the radio, and pretty much the power supply. We are now down to the IF and audio stages. What happens if you touch the first audio grid (accessable through the TV position of the Radio RV switch)? Do you get a hum or not??
::
::Lewis
:Hello Lewis. I,m not sure where you want me to touch to check for the hum.Please let me know. Thank you, Tim.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Somewhere on probably the back of the radio is a jack of some sorts marked "Television" On the schematic it looks like two pin jacks. There is a "Radio-Television" switch (in the old days they thouht you were going to use the radio audio section for TV audio) You can also use that jack for Phonographs. With the swith in the "TV" position, one of the jacks is connected directly to the volume control, and when touched should make a hum or buzz in the speaker.
Lewis
:::::::
:::::::The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:::::::
:::::::Are all tubes lit?
::::::
::::::
::::::
:::::::
:::::::Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:::::::
:::::::If you're getting static, I would guess that the rectifier and xfmr are working.
:::::::Doug
:::::::
::::::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
::::::
::::::
::::::Do these things first. Touch the ungrounded lug on the outside of the volume control. If you get a hum in the speaker, the power supply and the audio section are OK for now. If you get hum, then get a working AM radio and place it next to the Zenith, tuned to a blank space around 1100 kHz. Rock the tuning of the Zenith around 455 kHz lower than the good radio. You should hear the local oscillator at some point. Let us know the result of those actions, and we will be in a much better position to help.
::::::Lewis
::::::*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*<>*
::::::Oh, Oh, Easier way. Position the RAdio-Television swithc to the TV position, see if you can get the hum from one of those terminals. Volume up, of course.
::::::Lewis
::::Lewis, Thank you for the reply. I did get a working radio, and set to @1100kHz, and rocked the Zenith dial.I did get the oscillator sound-on the good one- I am assuming that is what was to happen. I get no volume at all. As I turn the volume control, the static stays the same. Thank you, Tim
:::
:::
:::~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:::
:::Oh, GOOD,GOOD! We have eliminated the most complicated part of the radio, and pretty much the power supply. We are now down to the IF and audio stages. What happens if you touch the first audio grid (accessable through the TV position of the Radio RV switch)? Do you get a hum or not??
:::
:::Lewis
::Hello Lewis. I,m not sure where you want me to touch to check for the hum.Please let me know. Thank you, Tim.
:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:Somewhere on probably the back of the radio is a jack of some sorts marked "Television" On the schematic it looks like two pin jacks. There is a "Radio-Television" switch (in the old days they thouht you were going to use the radio audio section for TV audio) You can also use that jack for Phonographs. With the swith in the "TV" position, one of the jacks is connected directly to the volume control, and when touched should make a hum or buzz in the speaker.
:Lewis
Hello Lewis. IT WORKS!!! Please see my response to Doug Criner as to what the problem was. I really appreciate your help, and I'll look forward to your help as I will probably have other issues. Thanks again. Tim
:
:The schematic doesn't show voltages. But measure the DC voltage across C24 to see if you have high-voltage B+. If it's there, then the rectifier is working.
:
:Are all tubes lit?
:
:Double and triple check all the wiring involved in your cap replacements. You could have two problems - the original one and maybe a wiring error on top of that. Wiring errors a very easy to make.
:
:If you're getting static, I would guess that the rectifier and xfmr are working.
:Doug
:Hello Doug. Thank you for your reply. I did check the wiring, and I believe that it is OK. All of the tubes do light up. The DC voltage across C24 is 260VDC. I don't know if that is what it should be. When I say that I get static, it is not very loud, and the volume control does not change it. Thank you for your help. Tim
::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
Steve
:Steve
Steve
:Steve
Hello Steve. Thank you for the voltage chart. Most of the voltages were in the ball park, however, some where way out there. On the 1232 tube, both of the readings that should have been 0.5 were 79.On the 6F6G tube, the one that should have been -20 was 236,and the one that should have been -1 was -19.4.On the 6F5G tube the one that should have been 100 was 27. I hope this means something to you. Thank you, Tim.
It appearst that there are several problems here. But we need to work on just one at a time, and not jump to the next problem until the first one is fixed.
First, before doing anything else, remeasure all your voltages to make sure that you are on the right pins. Make sure that your DMM is on DC. The voltage diagram is shown looking from the bottom of the chassis, and pins are numbered clockwise from the index.
But based on your first measurements, here's what I came up with:
6F5 (1st audio) - pin 4, the plate is way low (27 vs. 100V). Check the voltages, working backwards from the 6F5 plate toward the cathode (pin 8) of the 6X5 and find out where the voltage is getting lost. Check the value of R11 (220K). DON'T JUMP TO OTHER PROBLEMS UNTIL THIS ONE IS SOLVED.
6F6 (final audio) - I believe that Zenith's voltage diagram is WRONG. It shows 220V on pin 4, which is the grid. 220V should be on the plate, which is Pin 3. Pin 4, the grid, should be -20V. Recheck these - maybe you're OK.
There are two 6F6 pins that should read the same voltage, since they are tied together, internally - Pins 5 and 8. Check the values of R12 and R5.
1232 (RF amp) - somehow, the cathode (Pin 7) and the supressor (Pin 4), which are tied together, are too high. Check the values of R1, R20, and the operation of the local/distant switch.
Doug
::Voltage chart and alignment info on it's way. Let us know what you find out.
::Steve
:Hello Steve. Thank you for the voltage chart. Most of the voltages were in the ball park, however, some where way out there. On the 1232 tube, both of the readings that should have been 0.5 were 79.On the 6F6G tube, the one that should have been -20 was 236,and the one that should have been -1 was -19.4.On the 6F5G tube the one that should have been 100 was 27. I hope this means something to you. Thank you, Tim.
It wouldn't be the first time a Zenith chart was wrong. Also check the candohm resister strip which frequently has sections open.
Steve
:
:It appearst that there are several problems here. But we need to work on just one at a time, and not jump to the next problem until the first one is fixed.
:
:First, before doing anything else, remeasure all your voltages to make sure that you are on the right pins. Make sure that your DMM is on DC. The voltage diagram is shown looking from the bottom of the chassis, and pins are numbered clockwise from the index.
:
:But based on your first measurements, here's what I came up with:
:
:6F5 (1st audio) - pin 4, the plate is way low (27 vs. 100V). Check the voltages, working backwards from the 6F5 plate toward the cathode (pin 8) of the 6X5 and find out where the voltage is getting lost. Check the value of R11 (220K). DON'T JUMP TO OTHER PROBLEMS UNTIL THIS ONE IS SOLVED.
:
:6F6 (final audio) - I believe that Zenith's voltage diagram is WRONG. It shows 220V on pin 4, which is the grid. 220V should be on the plate, which is Pin 3. Pin 4, the grid, should be -20V. Recheck these - maybe you're OK.
:
:There are two 6F6 pins that should read the same voltage, since they are tied together, internally - Pins 5 and 8. Check the values of R12 and R5.
:
:1232 (RF amp) - somehow, the cathode (Pin 7) and the supressor (Pin 4), which are tied together, are too high. Check the values of R1, R20, and the operation of the local/distant switch.
:Doug
:
:::Voltage chart and alignment info on it's way. Let us know what you find out.
:::Steve
::Hello Steve. Thank you for the voltage chart. Most of the voltages were in the ball park, however, some where way out there. On the 1232 tube, both of the readings that should have been 0.5 were 79.On the 6F6G tube, the one that should have been -20 was 236,and the one that should have been -1 was -19.4.On the 6F5G tube the one that should have been 100 was 27. I hope this means something to you. Thank you, Tim.
Hello Doug, and thank you again. I did recheck voltages, and they were correct. Pin 4 of 6F5G is 27 VDC. R11 checks out at 228K. I haven't gone any further as you suggested. Let me know what you think. Thank you, Tim.The 6F6 readings were pin 3-236V, pin4-257V.
Using the schematic, try to understand the logic of why I'm suggesting the following test procedure. This is the kind of thought process that is necessary to perform systematic troubleshooting. It's best to go slowly, make notes of everything you do, and record the results.
The basic idea is to disconnect, one at a time, each component connected to the 6F5 plate, and see if that causes the plate voltage comes up to where it should be, 100V. If and when that happens, we will have isolated the problem to a particular area.
First, pull the 6F5 tube, and check the voltage on Pin 4. Is it still low? If not, then stop. If the voltage is still low, reinstall the 6F5, and continue.
Next, check the voltage to ground from each end of R11. One end, the one connected to the 6F5 plate, presumably will measure that 27V that you reported.
Now measure the voltage at the other end of R11. Do you get 200V or so? If not, stop. If you do get 200V or so, then change the position of the tone-control switch labeled "Normal." Does the voltage come up on the 6F5 plate?
If not, then do these three things, one at a time:
1. Temporarily disconnect the end of C11 that is connected to the 6F5's plate. Does the plate voltage come up? If not, then reconnect C11, and then go to step 2.
2. Temporarily disconnect the end of C14 that is connected to the 6F5 plate. Does the plate voltage come up? If not, then reconnect C14, and go to step 3.
3. Temporarily disconnect the end of C9 that is connected to the 6F5 plate. Does the 6F5 plate voltage come up?
Is there anything connected to the 6F5 plate that we haven't tried? There shouldn't be unless there is a wiring error.
Keep us posted.
Doug
:Hello Doug, and thank you again. I did recheck voltages, and they were correct. Pin 4 of 6F5G is 27 VDC. R11 checks out at 228K. I haven't gone any further as you suggested. Let me know what you think. Thank you, Tim.The 6F6 readings were pin 3-236V, pin4-257V.
Doug
Doug
:Doug
Hello Doug -SUCCESS YES!!!! One thing in common that evryone suggested time and again was to recheck caps ans wiring. On about the fourth time through I found a single strand of wire that had come unraveled from another wire that was touching a lead of one of the caps. I bent it out of the way, not even positive if it had been touching, but it had, because the radio is working fine. Thank you Doug and evryone else that helped with their suggestions and time involved. I don't take that lightley and really do appreciate it. I still have several things to do on the radio. One thing is that the dial alignment is way off. It looks like I should be able to pull the pointer off and reposition it, but I don't want to pull too hard and break it. Any suggestions? Also I need to replace the dial cord,or does this unit take belts? It looks like it could take 2 belts. It has a cord now, but slips badly. The cabinet is in very good shape, but it could be polished and shined. Any suggestions? Thanks again everyone. One happy dude-Tim B.
::
::It appearst that there are several problems here. But we need to work on just one at a time, and not jump to the next problem until the first one is fixed.
::
::First, before doing anything else, remeasure all your voltages to make sure that you are on the right pins. Make sure that your DMM is on DC. The voltage diagram is shown looking from the bottom of the chassis, and pins are numbered clockwise from the index.
::
::But based on your first measurements, here's what I came up with:
::
::6F5 (1st audio) - pin 4, the plate is way low (27 vs. 100V). Check the voltages, working backwards from the 6F5 plate toward the cathode (pin 8) of the 6X5 and find out where the voltage is getting lost. Check the value of R11 (220K). DON'T JUMP TO OTHER PROBLEMS UNTIL THIS ONE IS SOLVED.
::
::6F6 (final audio) - I believe that Zenith's voltage diagram is WRONG. It shows 220V on pin 4, which is the grid. 220V should be on the plate, which is Pin 3. Pin 4, the grid, should be -20V. Recheck these - maybe you're OK.
::
::There are two 6F6 pins that should read the same voltage, since they are tied together, internally - Pins 5 and 8. Check the values of R12 and R5.
::
::1232 (RF amp) - somehow, the cathode (Pin 7) and the supressor (Pin 4), which are tied together, are too high. Check the values of R1, R20, and the operation of the local/distant switch.
::Doug
::
::::Voltage chart and alignment info on it's way. Let us know what you find out.
::::Steve
:::Hello Steve. Thank you for the voltage chart. Most of the voltages were in the ball park, however, some where way out there. On the 1232 tube, both of the readings that should have been 0.5 were 79.On the 6F6G tube, the one that should have been -20 was 236,and the one that should have been -1 was -19.4.On the 6F5G tube the one that should have been 100 was 27. I hope this means something to you. Thank you, Tim.
:Hello Doug, and thank you again. I did recheck voltages, and they were correct. Pin 4 of 6F5G is 27 VDC. R11 checks out at 228K. I haven't gone any further as you suggested. Let me know what you think. Thank you, Tim.The 6F6 readings were pin 3-236V, pin4-257V.
Tim, Triple check your wiring against the schematic. I had a cap landed on the wrong pin of a coil and it had me stumped for a long time. Quadruple check it. Reland every wire in your mind.
:::
:::It appearst that there are several problems here. But we need to work on just one at a time, and not jump to the next problem until the first one is fixed.
:::
:::First, before doing anything else, remeasure all your voltages to make sure that you are on the right pins. Make sure that your DMM is on DC. The voltage diagram is shown looking from the bottom of the chassis, and pins are numbered clockwise from the index.
:::
:::But based on your first measurements, here's what I came up with:
:::
:::6F5 (1st audio) - pin 4, the plate is way low (27 vs. 100V). Check the voltages, working backwards from the 6F5 plate toward the cathode (pin 8) of the 6X5 and find out where the voltage is getting lost. Check the value of R11 (220K). DON'T JUMP TO OTHER PROBLEMS UNTIL THIS ONE IS SOLVED.
:::
:::6F6 (final audio) - I believe that Zenith's voltage diagram is WRONG. It shows 220V on pin 4, which is the grid. 220V should be on the plate, which is Pin 3. Pin 4, the grid, should be -20V. Recheck these - maybe you're OK.
:::
:::There are two 6F6 pins that should read the same voltage, since they are tied together, internally - Pins 5 and 8. Check the values of R12 and R5.
:::
:::1232 (RF amp) - somehow, the cathode (Pin 7) and the supressor (Pin 4), which are tied together, are too high. Check the values of R1, R20, and the operation of the local/distant switch.
:::Doug
:::
:::::Voltage chart and alignment info on it's way. Let us know what you find out.
:::::Steve
::::Hello Steve. Thank you for the voltage chart. Most of the voltages were in the ball park, however, some where way out there. On the 1232 tube, both of the readings that should have been 0.5 were 79.On the 6F6G tube, the one that should have been -20 was 236,and the one that should have been -1 was -19.4.On the 6F5G tube the one that should have been 100 was 27. I hope this means something to you. Thank you, Tim.
::Hello Doug, and thank you again. I did recheck voltages, and they were correct. Pin 4 of 6F5G is 27 VDC. R11 checks out at 228K. I haven't gone any further as you suggested. Let me know what you think. Thank you, Tim.The 6F6 readings were pin 3-236V, pin4-257V.
:Tim, Triple check your wiring against the schematic. I had a cap landed on the wrong pin of a coil and it had me stumped for a long time. Quadruple check it. Reland every wire in your mind.
Neal-The radio is working!!! Thank you for your help. Check my response to Doug to see what the problem was. Thank you for all of your help. Tim
I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
Doug
::Neal: Could it be your output transformer has an open? Are you using the original Speaker? There is a 4 wire and a 5 Wire hookup on different radios. The 6f6g tube powers the speaker so a problem there could effect your voltages.
:
:I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
That's it exactly. If he was trying to use a 4 wire speaker where a 5 wire is needed, one of the pins on the 6f6 tube would be missing B+. It seems as if I haven't read enough feedback on his problem.
Neal, that's a good thought, but the 6F6 (power output tube) is, according to Tim, getting 230V B+ to it. That voltage must be going through the primary of the output xfmr and the speaker field coil. If either were open, then I don't there would be B+ getting to the the 6F6.
:Doug
:
:
:::Neal: Could it be your output transformer has an open? Are you using the original Speaker? There is a 4 wire and a 5 Wire hookup on different radios. The 6f6g tube powers the speaker so a problem there could effect your voltages.
::
::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:That's it exactly. If he was trying to use a 4 wire speaker where a 5 wire is needed, one of the pins on the 6f6 tube would be missing B+. It seems as if I haven't read enough feedback on his problem.
:Neal, that's a good thought, but the 6F6 (power output tube) is, according to Tim, getting 230V B+ to it. That voltage must be going through the primary of the output xfmr and the speaker field coil. If either were open, then I don't there would be B+ getting to the the 6F6.
::Doug
::
::
::::Neal: Could it be your output transformer has an open? Are you using the original Speaker? There is a 4 wire and a 5 Wire hookup on different radios. The 6f6g tube powers the speaker so a problem there could effect your voltages.
:::
:::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
Hello Neal. The speaker is a 4 wire, and I am assuming it is the original speaker. Thank you for your help. Tim
::That's it exactly. If he was trying to use a 4 wire speaker where a 5 wire is needed, one of the pins on the 6f6 tube would be missing B+. It seems as if I haven't read enough feedback on his problem.
::Neal, that's a good thought, but the 6F6 (power output tube) is, according to Tim, getting 230V B+ to it. That voltage must be going through the primary of the output xfmr and the speaker field coil. If either were open, then I don't there would be B+ getting to the the 6F6.
:::Doug
:::
:::
:::::Neal: Could it be your output transformer has an open? Are you using the original Speaker? There is a 4 wire and a 5 Wire hookup on different radios. The 6f6g tube powers the speaker so a problem there could effect your voltages.
::::
::::I purchased a Zenith 8S463 in non working order. The first thing I did was replace all of the caps. When I turn it on, I just get a little static, no stations, or volume at all. In reading about this particular radio, it seems that the 6X5G tube was prone to failure, and caused problems with the transformer. I was wondering how I go about checking this, voltages, etc. I am still a novice at this, and would appreciate any help I can get. Thank you, Tim.
:
:Hello Neal. The speaker is a 4 wire, and I am assuming it is the original speaker. Thank you for your help. Tim
Hello Tim, If you have the right voltages on your 6f6 pins then you're most likely ok there. I had a nightmare of a time trying to make a 4 wire Speaker w/output xformer work on a Zenith radio that wanted a 5 wire speaker. The fifth wire being the center tap of the primary side of the output xformer. It just ties in with one of the legs of the same and plugs into the chassis in a 4 prong plug. I had low voltage on one of the 6f6g pins where it should have been b+. The 5 wire design fixed that.
Sir Tim…
Looks like you didn’t pick the very easiest set to trouble shoot, what with the unit requiring the use of a somewhat less than perfect referencing of schematics from Riders, additionally, the fine detail on that sheet of voltages at the tube sockets may be less than desired…..BUT…. it should be a treasure when you finally get it going
From that aspect, initially refer to the enhanced drawing enclosed, and we can correct or add in voltages as time progresses. All of the tube indexes are shown in respect to a tubes pins 1and 8 and those have been marked up with red numbers.
Top chassis voltages reference:
The next consideration would be to refer to the new schema below and initially notice the derivation of the raw B+ from the cathode of the 6X5 and then the initial branching off to two points, one would be the field coil of the speaker which is located just above that point and the other point would be the R19 resistor which feeds the dotted red buss to the left over to the junction of R15 and R16…now we know that reduced B+ is present all along this buss and down to the even less B+ being crated for the buss that trails down from R16….because you said that the local oscillator emissions could be picked on a close coupled receiver.
You can see that mentioned buss [Back-Red-Red-Black] turns to the left at the bottom and then makes a series pass thru two feedback windings of oscillator circuits and eventually ends up at the 2nd grid (ersatz plate) of your 6A8 ‘s 3 tube elements that are used for its local oscillator circuit.
Now, let’s go back to the point where your raw B+ entered the field coil of the speaker, it then passes thru and ends up being more fully filtered of ripple with that inductance and the C24 output filter capacitor and then the B+ voltage passes upward via the [ dashed red mark up ] B+ buss and feeds the 6F6 screen grid and also the output transformer with that voltage passage on thru it to the plate circuit of the 6F6…I believe that you have confirmed the presence of B+ at both that units’ plate an screen grid…right ?
Now looking at the schema half way between the AF out transformer and the spkr field coil … the dashed red B+ supply buss juncture routes to the left and
Its first routing is upward to feed thru R11 your plate load resistor that feeds the plate of the 6F5 1st AF amp.
The main B+ buss then feeds left to the point where it goes upward to feed the
supply side of the 2nd I.F. transformer…it then passes thru the transformer winding to the plate of its 6K7 tube.
Check the screen grid of that tube and you will see that it derives its supply from yet a different source, track its [Red-Black dot] line down and one jog to the left and then one jog down and then one jog to the left and then a jog down and past the 6U5 to its right and you will end up down at R15… the companion point where the B+ was reduced by R16 to feed the oscillator circuit we already covered.
There was one additional juncture up at the point of the 6K7 screen grid connection, where that buss also tied into R6 to provide a reduced voltage level to grids G3&5 of the 6A8.
Getting back on the main B+ buss again, we see it tying into R7 which feeds the 1st I.F. transformer and flows on thru it to the plate of the 6A8, that same voltage level also coincidentally connects over to R3 to feed the broadly resonant RF coil in the plate circuit of the R.F. amplifier stage …with voltage reaching the 1232 plate.
The next branch of the main B+ is to feed down and supply plate and target voltage to the 6U5…….MMMmmmmm…. Magic Tuning Eye.
That only leaves the last tie- in of the main B+ buss, to be a feed to the R5 dropping resistor to feed screen voltage to the 1232 R.F. amp tube.
Soooo…now check out all of the branches and confirm that your B+ is dividing down and feeding all of these points.
A different aspect of the receiver to inspect now is the manner in which they derive negative biasing voltages to feed throughout the sets circuitry.
One would most conventionally expect to see the secondary high voltage center tap of the power transformer be routed directly to ground, in this case they have the center tap feeding into a series string of three resistors so that
There will be a negative voltage level developed across the string, with the highest value at reference [A], a mid level value at [B],and the lowest level
At the resistor that is closest to ground potential , which would be [C].
The highest level is required for the biasing to the 1st grid of the of the 6F6 AF output tube which is routed up from [A] via series R5 and R12 with a bit of in line decoupling to ground via C12.
The next less bias requirement is for the 6F5’s 1St AF tubes, 1St grid circuitry… it starting at [B] and then passing up via series pair R6 and R8, with C10 being their decoupling capacitor.
That only leaves [C] level to be accounted for, with it completing the ground loop of the cathodes of the 6F6---6F5---6J5---6U5 along with a bias being supplied to G4 of the 6A8 and a additionally supplying a counterpoise referencing bias to the AVC circuitry to get a wider AVC voltage swing .
Getting back to the fact of your receiving the carrier of the local oscillator, I’m not going to search back, but did you also confirm audio gain thru the system by the application of a moistened fingertip to the 1st grid cap of the 6J5.
If so, lets go the next step, which would be the firing up of the Zenith set and placing that AM pocket transistors’ enclosed ferri-loop antenna up right against the plate cap of the 6K7 and tune the xstr unit into the second harmonic of 455 Khz which would be 910 KHz. Now, if your mixer and the 6K7 I.F. amp is working in that Zenith set, there should be a healthy enough level of converted RF to hear stations come in on the xstr monitoring set as you tune across the AM band with the Zenith receiver.
If no luck…feed us the voltages monitored at the B+ nodes of the set…plates and screens… along with the negative bias voltages metered at green marked up test points [A]-- [B]-- [C].
Standing by….
Schematic markup of the sets B+ routing :
Routing of the Detected audio and AVC Busses:
Along with…….
Supplemental info on derived bias sources from the utilization of a stacked power supply design :
:
73's de Edd