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:: :: :: :: :: :: :: : : Sir Edd: : : Getting back with you on the Zenith radio that had the filter condenser taken out and not put back in the circuit. The radio was a Zenith model 4G903 Chassis 4F40. I used 4 electrolyic caps to replace the one 4 section cap.I think i got them wired back in as you pointed out to me.I checked out the tubes and found them good, i still have an open circuit and it is the 1 meg. resistor that comes off of transformer T1 on tie-point 4# i dont know where it goes.This resistor is in the circuit with 3 more 1 meg resistors.They are listed as resistor 2's. The off and on switch works and when on i get about 80 volts from the sel. rect.no sound from the speaker, or buzz. It also looks like i have no fil. voltage to the tubes.I know that the fil. voltage on tubes are 1 volt, and max is 3 volts. Even with the lights off i see no light to the tubes. I also put the one black wire from the volume control to the (BLUE)buss line.The other black wire coming from one end of the antenna i put to ground.When i would take it from ground i would loose the 80 volts coming from the sel.rect.Then i though i would try to put it also on the (BLUE) buss line. When i did i saw the 3v4 tube light up bright and found out i burnt it out. So this is where i am at now, and i need more help in getting this radio up and going. All help appreciated. : : Thanking You : Randall Hornback :: :: :: :: :: ::Sir Roger. . . . . :: :: ::The one with the old trade schools silly scope kit . . . ? :: :: ::Considering having wiring the multiple caps to a terminal strip and using their common grounding to the Floating B negative portion of the set . . . .(Heavy [BLUE] buss) . . . as Cap C17 holds it above ground for DC potential but AC and RF will couple thru via C17. :: :: :: :: ::I made a clarified mark up of that area of concern in which case, you may find that the missing canned filter had R8 . .R9 . .and R10 resistors intertwined and wired between the terminals and have left along with the filter. :: :: ::Possibly R6 up above may be gone also. :: :: ::Sounds like you may have already pinpointed all connections, but I color highlighted each buss also. :: :: ::Don't know if that incoming 140 0hms input from the Selenium rectumfire is there also ? :: :: :: :: :: ::From your last supplied info, looks like of those two mystery black wires: :: :: ::1 . . .One of them must have been the one which WAS going to the common ground trminal on the canned filter which we NO longer have. :: :: ::2 . . .The other one would have went up to the low side of the vol-you-me control which I have assigned as being tied into the [BLUE] buss. :: :: :: ::Hope this info might "heps" you out. :: :: :: :: ::73's de Edd :: :: :: :: ::

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:: :: :: :: ZENITH Filter Hookup: :: :: :: :: :: :: :: :: :: ::

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:::::::I need help in finding a electrolytic capacitor for a Zenith radio model 4G903 chassis 4F40. The part no. on the capacitor is 22-1741. If you have one or know where i can find one please let me know.
:::::::
::::::: Thanking You
::::::: Randall Hornback
:::::::
::::::: Email hotralston@att.net
:::::::
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::::::That is the multisection filter cap and it is unlikely you wll be able to find one. You will need to replace it with 4 individual caps which are rated at 60, 20 40uf at 150 volts and 200uf at 10 volts.
::::::Johnnysan-
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:::::
::::: Hi Johnnysan, a big thank you for the information you gave my way on the multisection filter cap.
:::::
:::::The other problem i have is that who ever had the radio before me took out the filter cap and did not put it back in the radio oe leave it with the radio.And they did not leave a schematic on how to wire the cap back in.I have a schematic on the radio but having trouble how to hook up wires, and caps, and resistors if i use the 4 individual caps. And does the ground to these caps go to ground or do they have to be above the ground?.I need all the help you can give me, and will appreciate it very much
:::::
::::: Thanking You
::::: Randall Hornback
:::::
::::::
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::
::::Hi Randall,
::::
::::How I appreciate your situation. It is no fun when a part has been removed and you are left to guess how the wiring to the part was arranged. You will need to carefully examine the schematic and hopefully you have a parts list to guide you. Look very carefully for the "GROUND" Symbol which looks like an arrow pointing straight down. The "arrow" most commonly is made up of 3 rows of dashed lines pointing down. Sometimes a "trapezoid" symbol is specifically used to denote the Chassis Ground.
::::
::::"Floating" grounds on filter capacitors are also very common. Your set may even contain a mix of chassis and floating grounds. Any where that your schematic indicates chassis grounds, those electrolytics should be chassis grounded. And if the schematic shows no "ground" symbol on any given filter cap negative lead DO NOT ground it to your chassis!
::::
::::Above all, be very careful not to wire a filter cap backwards. The negative lead in virtually all cases is the "ground" lead - the correct polarity must be observed or the Electrolytic Capacitor may blow apart.
:::
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::: Hi Daniel,
:::
:::I do appreciate the load of information you sent my way.I will do my best to check out the schematic and study where the wires,caps,resistors go to the 4 individual filter caps i will used to replace the filter cap that was taken out of the circuit.
:::
:::If i am looking at the schematic right it has both grounds, the floating ground and the ground ground.The filter was hook to the floating ground between cap 12 .047 and cap 17 .05 this is where i will put the neg.leads of the 4 individual caps i will be useing here.
:::
:::Daniel i have 2 black wires coming to where the filter was.One wire comes from the vol. control on outside leg, the other black wire comes from the end of antenna where will these wires hook up at?. Will appreciate any and all help.
:::
::: Thanking You
::: Randall Hornback
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::: ::: ::: ::: ::: ::: ::: ::: :: SIR EDD: :: :: HI EDD, I AM BACK AS YOU TOLD ME TO DO ON THE ZENITH RADIO 4G903.I HOOK-UP ALL THE WIRES, AND RESISTORS, AND CAPS IN THE CIRCUIT AS THE BEST I KNEW HOW.EDD I GOT SOME TUBES AND REPLACED THE BAD ONES THE 3V4, AND I FOUND A VERY WEAK 1S5 ALSO.AFTER REPLACEING THEM I CHECKED OUT THE FIL. CIRCUIT TO SEE IF I HAD THE FIL. VOLTAGE, AND FOUND OUT THAT I DID NOT.I CHECKED THE VOLTAGE COMING OFF OF RESISTORS 8,9,10 HOOKED TO WH-BL WIRE GOING TO S-1 TERMINAL 9# AND THEN GET'S SWITCHED THRU IT AND UPWARDS OUT OF TER.8#,THEN THAT 7.5 VDC CONNECTS TO PIN 7# OF 3V4 TUBE AND FLOWS THRU TO COME OUT ITS PIN 1#. EDD I HAD ABOUT 65 VOLTS COMING OFF OF RESISTOR 10 INTO THE WH-BL WIRE GOING TO S-1 ON TERMINAL 9# ALSO ON TER. 8# OF SWITCH,BUT AS I SAID NO FIL VOLTAGE OF ANY KIND ON THE FIL STRING OF TUBES.EDD IF THIS IS WHERE THE 7.5 VOLTS FOR FILAMENT VOLTAGE IS SUPPOSE TO BE I DONT HAVE IT THERE IT IS ABOUT 65 VOLTS HERE. :: :: NOW EDD, TO COMFIRM THIS IN REGARDS OF THE TWO BLK. WIRES THAT WERE NOT HOOK UP IN THE CIRCUIT.THE ONE COMING OFF OF VOLUME CONTROL I PUT IT ON THE BLUE BUSS LINE.AND THE OTHER ONE TO GROUND.I THOUGHT THE ONE BLK. WIRE WAS COMING FROM THE ANTENNA BUT I WAS WROUNG, AND YOU WAS RIGHT.IT WAS A GREEN WIRE AND WHITE WIRE COMING FROM THE ANTENNA.THE GREEN GOING TO THE GRID OF PIN 5# OF THE 1R5 TUBE.AND THE WHITE WIRE GOING TO THE L-2 OSC.COIL.THE OTHER BLK WIRE THAT I PUT TO GROUND WAS COMING FROM THE OFF-ON SWITCH S-2. :: ::EDD MY BIG QUESTION NOW IS WHERE DID MY FIL. VOLTAGE GO?.WHAT CIRCUIT WOULD BE OPEN NOW BEING I HAVE NO FIL. VOLTAGE?. :: ::EDD I GET ABOUT 65 VOLTS DC OFF OF RES.8 AND SHOULD I BE GETTING ABOUT THE SAME VOLTS DC OFF OF COMMON RETURN GROUND? BECAUSE THAT IS WHAT I AM GETTING THERE. I HAVE GIVEN YOU SOME QUESTIONS THAT I NEED HELP ON, ALL HELP WILL BE APPRECIATED. :: :: THANKING YOU :: RANDALL HORNBACK :: ::: ::: ::: ::: :::Sir Randall. . . . . ::: ::: ::: :::I will just fill in, just below your concerned statements , such that all will get covered: :::Plus you can still view the schematic at the bottom, OR, open it up in another window on your browser and then be able to rapidly click/toggle betwixt this text and the schema. ::: ::: ::: ::: :::I still have an open circuit and it is the 1 meg. resistor that comes off of transformer T1 on tie-point 4# ::: ::: :::I dont know where it goes. ::: ::: :::This resistor is in the circuit with 3 more 1 meg resistors.They are listed as resistor 2's. ::: ::: ::: :::OK . . . I am specifically looking at ALL of the commonly shared R2 resistor designators and I see only one unit that would relate to its being associated with the pulling out of a canned electrolytic in times past and its having left a rats nest of unterminated items; inclusive of the expected 4 connections that were initially being made to the filter condenser proper. ::: ::: ::: ::: :::The off and on switch works and when on I get about 80 volts from the sel. rect,no sound from the speaker, or buzz. ::: ::: ::: :::Understood . . . ::: ::: ::: ::: It also looks like i have no fil. voltage to the tubes.I know that the fil. voltage on tubes are 1 volt, and max is 3 volts. ::: ::: :::Even with the lights off I see no light to the tubes. ::: ::: ::: :::You are not alone on that aspect. . .in the SEEING of the dull red filament on one of those 1.4 volt tubes even in a pitch dark room AFTER the 'ole eyes finally dilate. ::: ::: :::Worse yet, sometimes, the tube manufacturing process, additionally leaves the top of the tube envelope either darkened or silvered. Hard to circumvent by then viewing from the side mica support discs or up from the bottom. ::: ::: ::: :::I also put the one black wire from the volume control to the (BLUE)buss line. ::: ::: ::: :::That looks right . . . . and is also logical that they saw that metal shell of the old electrolytic and its potential four . . .count 'em FOUR . . . twist tab grounds and said . . . Hey lets make that ground to one of those tabs !. ::: ::: :::No problem then, until that can is pulled and the resultant, floating, loose wire just mentioned. ::: ::: ::: :::The other black wire coming from one end of the antenna i put to ground. ::: ::: ::: :::Now confirm this for me . . . . as the schema is saying . . .they assigned the top "HOT" RF connection of the loop as being a GREEN wire which goes to the input grid of the 1R5. Understood. ::: ::: :::BUT . . . looking just below the oscillator coil on the route of the "cold" wire downwards from the bottom of the loop antenna . . . they are assigning it a WH . . (ite) color coding, instead of your mentioned black. Physically track down the wire coming down from the bottom of the loop and confirm its color coding and termination point. ::: ::: :::BTW . . . ALL of these R2 designated resitors are being commonly involved in either isolating the AVC feed of the set or with one being used as a leg of a voltage divider for the AVC circuitry. ::: ::: :::Lastly . . . . I agree on the count of them as being 4 items and with my strongest suspicion of the floating ended R2 as being the one on the schematic which goes from your mentioned #4 of the 1st IF transformers secondary and is routed to the right, over to the BLUE buss ( Common floating B minus buss). ::: ::: :::FIO . . the others are: ::: ::: :::Next closest R2's are the two placed in series, the first R2 of which also ties into that same #4 of the 1st IF transformers secondary and then it goes down and ties into another R2 that routes to the right and then up and into term #6 of the secondary of the 2nd IF transformer. That terminal is where the main AVC is derived from. ::: ::: :::The last R2 is deriving a counterpoise bias voltage, that the AVC buss swings against, its being received at terminal #8 of the S1 . . . AC power / Battery power switch. ::: ::: ::: :::When i would take it from ground i would loose the 80 volts coming from the sel.rect.Then i though i would try to put it also on the (BLUE) buss line. ::: ::: :::When i did i saw the 3v4 tube light up bright and found out i burnt it out. So this is where i am at now, and i need more help in getting this radio up and going. All help appreciated. ::: ::: ::: :::Now that is the point where I believe that what you did was to have erroneously made a connection between the :::pin 1 of the 3V4 and the BLUE buss ( Common floating B minus buss). ::: ::: :::That THEN put a full ~7.5 VDC across your 2.8 VDC rated 3V4's filament :::. . . Toobie go Phhzzzzzzzzzzt . . . and makie a Flashie-Flashie. ::: ::: ::: :::It shouldn't have affected the others in the series string, as you then shorted out filament power from then even reaching them. ::: ::: ::: ::: :::DETAILS: ::: ::: :::Here is a further breakdown of the sets filamental supply flow: ::: ::: :::B+ power initially flows thru the Series resistor string of R8-R9-R10 to get voltage dropped and finally come out and flow outwards, to the right as designated wire WH-BL and terminate at S1 terminal 9 and then get switched thru it and upwards out of terminal #8. ::: ::: :::That ~7.5 VDC connects to pin 7 of the 3V4 and flows thru to come out its pin 1. ::: ::: :::That flow is then over to the left to connect to 1R5's pin 7, with the additional picking up of some filtering / decoupling via your 200 mike down on the Green buss. ::: ::: :::After passing thru the 1R5 the path is out of its pin 1 and into the 1U4 pin 7 and then out its pin 1, with the further flow then being over to the right and then up, to come in pin 7 of the 1S5, flow thru and exit via pin 1 :::and then FINALLY . . . whewwwwww . . its getting grounded via the BLUE buss. ::: ::: :::Therewith . . . all of your tubes filaments are being series fed from ~7.5 VDC and additionally maintaining the proper circuitry design tenet of having the RF converter tubes filament being well bypassed/ decoupled along with the audio preamp and detector tube having its filament being as close to ground as is possible. ::: ::: ::: :::Until such time as you have a another 3V4, in the interim, you could pre evaluate the filament supply by having the old 3V4 in circuit . . .(open filament . . . and STILL not feeling to well inside ) . . . but then you place a 150 ohm 1/2 --> 1 watt resistor from pin 7 of the 3V4 to the floating common B- buss (BLUE). ::: ::: :::Now, on power up, it should be reading ~ 7.5 VDC across its simulated filament string load, thereby signifying that you are in order on the supply level, once you get the next 3V4 to put in circuit. ::: ::: ::: ::: :::Check out the sets wiring and . . . . .Talka to me . . . . mamma mia ! ::: ::: ::: ::: ::: ::: :::73's de Edd ::: ::: ::: ::: :::

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::::: ::::: ::::: ::::: ::::: ::::: ::::: :::: :::: Sir Edd: :::: :::: Getting back with you on the Zenith radio that had the filter condenser taken out and not put back in the circuit. The radio was a Zenith model 4G903 Chassis 4F40. I used 4 electrolyic caps to replace the one 4 section cap.I think i got them wired back in as you pointed out to me.I checked out the tubes and found them good, i still have an open circuit and it is the 1 meg. resistor that comes off of transformer T1 on tie-point 4# i dont know where it goes.This resistor is in the circuit with 3 more 1 meg resistors.They are listed as resistor 2's. The off and on switch works and when on i get about 80 volts from the sel. rect.no sound from the speaker, or buzz. It also looks like i have no fil. voltage to the tubes.I know that the fil. voltage on tubes are 1 volt, and max is 3 volts. Even with the lights off i see no light to the tubes. I also put the one black wire from the volume control to the (BLUE)buss line.The other black wire coming from one end of the antenna i put to ground.When i would take it from ground i would loose the 80 volts coming from the sel.rect.Then i though i would try to put it also on the (BLUE) buss line. When i did i saw the 3v4 tube light up bright and found out i burnt it out. So this is where i am at now, and i need more help in getting this radio up and going. All help appreciated. :::: :::: Thanking You :::: Randall Hornback ::::: ::::: ::::: ::::: ::::: :::::Sir Roger. . . . . ::::: ::::: :::::The one with the old trade schools silly scope kit . . . ? ::::: ::::: :::::Considering having wiring the multiple caps to a terminal strip and using their common grounding to the Floating B negative portion of the set . . . .(Heavy [BLUE] buss) . . . as Cap C17 holds it above ground for DC potential but AC and RF will couple thru via C17. ::::: ::::: ::::: ::::: :::::I made a clarified mark up of that area of concern in which case, you may find that the missing canned filter had R8 . .R9 . .and R10 resistors intertwined and wired between the terminals and have left along with the filter. ::::: ::::: :::::Possibly R6 up above may be gone also. ::::: ::::: :::::Sounds like you may have already pinpointed all connections, but I color highlighted each buss also. ::::: ::::: :::::Don't know if that incoming 140 0hms input from the Selenium rectumfire is there also ? ::::: ::::: ::::: ::::: ::::: :::::From your last supplied info, looks like of those two mystery black wires: ::::: ::::: :::::1 . . .One of them must have been the one which WAS going to the common ground trminal on the canned filter which we NO longer have. ::::: ::::: :::::2 . . .The other one would have went up to the low side of the vol-you-me control which I have assigned as being tied into the [BLUE] buss. ::::: ::::: ::::: :::::Hope this info might "heps" you out. ::::: ::::: ::::: ::::: :::::73's de Edd ::::: ::::: ::::: ::::: :::::

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::::::::::I need help in finding a electrolytic capacitor for a Zenith radio model 4G903 chassis 4F40. The part no. on the capacitor is 22-1741. If you have one or know where i can find one please let me know.
::::::::::
:::::::::: Thanking You
:::::::::: Randall Hornback
::::::::::
:::::::::: Email hotralston@att.net
::::::::::
:::::::::
:::::::::
:::::
:::::
:::::
:::::
:::::::::
:::::::::That is the multisection filter cap and it is unlikely you wll be able to find one. You will need to replace it with 4 individual caps which are rated at 60, 20 40uf at 150 volts and 200uf at 10 volts.
:::::::::Johnnysan-
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:::::
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:::::::: Hi Johnnysan, a big thank you for the information you gave my way on the multisection filter cap.
::::::::
::::::::The other problem i have is that who ever had the radio before me took out the filter cap and did not put it back in the radio oe leave it with the radio.And they did not leave a schematic on how to wire the cap back in.I have a schematic on the radio but having trouble how to hook up wires, and caps, and resistors if i use the 4 individual caps. And does the ground to these caps go to ground or do they have to be above the ground?.I need all the help you can give me, and will appreciate it very much
::::::::
:::::::: Thanking You
:::::::: Randall Hornback
::::::::
:::::::::
:::::
:::::
:::::
:::::
:::::::Hi Randall,
:::::::
:::::::How I appreciate your situation. It is no fun when a part has been removed and you are left to guess how the wiring to the part was arranged. You will need to carefully examine the schematic and hopefully you have a parts list to guide you. Look very carefully for the "GROUND" Symbol which looks like an arrow pointing straight down. The "arrow" most commonly is made up of 3 rows of dashed lines pointing down. Sometimes a "trapezoid" symbol is specifically used to denote the Chassis Ground.
:::::::
:::::::"Floating" grounds on filter capacitors are also very common. Your set may even contain a mix of chassis and floating grounds. Any where that your schematic indicates chassis grounds, those electrolytics should be chassis grounded. And if the schematic shows no "ground" symbol on any given filter cap negative lead DO NOT ground it to your chassis!
:::::::
:::::::Above all, be very careful not to wire a filter cap backwards. The negative lead in virtually all cases is the "ground" lead - the correct polarity must be observed or the Electrolytic Capacitor may blow apart.
::::::
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:::::: Hi Daniel,
::::::
::::::I do appreciate the load of information you sent my way.I will do my best to check out the schematic and study where the wires,caps,resistors go to the 4 individual filter caps i will used to replace the filter cap that was taken out of the circuit.
::::::
::::::If i am looking at the schematic right it has both grounds, the floating ground and the ground ground.The filter was hook to the floating ground between cap 12 .047 and cap 17 .05 this is where i will put the neg.leads of the 4 individual caps i will be useing here.
::::::
::::::Daniel i have 2 black wires coming to where the filter was.One wire comes from the vol. control on outside leg, the other black wire comes from the end of antenna where will these wires hook up at?. Will appreciate any and all help.
::::::
:::::: Thanking You
:::::: Randall Hornback
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:: :: :: :: :: :: :: : : SIR EDD: : : HI EDD I WILL START OUT WITH A NEW PAGE AS TO WHERE I WAS AT WITH THE ZENITH RADIO. SINCE I LAST TALK WITH YOU HERE IS WHAT I HAVE DONE WITH THE RADIO AND WHERE I HAVE CAME TO.AS I SAID I GOT TUBES AND REPLACE THE 3V4, AND AND 1S5 THAT WAS WEAK.POWERED UP RADIO AND FOUND I HAD NO FIL. VOLTAGE GOING TO TUBES.CHECKED THE VOLTAGE COMING OFF OF RESISTORS 8,9,10.I HAD AROUND 80VOLTS + COMING OFF OF RESISTOR 8 AROUND 65 VOLTS + COMING OFF OF RESISTOR 9, AND THE SAME ON RESISTOR 10 WHERE I WAS SUPPOSE TO HAVE THE 7.5 VOLTS TO FIL. STRING.SO I DONE SOME CHECKING ON THE CIRCUIT AND FOUND THAT THE OTHER BLK. WIRE I PUT TO GROUND I PUT TO GROUND AND NOT THE COMMON BUSS GROUND.WHEN I PUT THE BLK WIRE TO COMMON BUSS GROUND I GOT A LITTLE INCREASE IN B+ VOLTAGE FROM RESISTOR 8, AND RESISTOR 9 AND ALSO GOT MY FIL. VOLTAGE ON THE OUTPUT OF RESISTOR 10.I DID NOT GET THE 7.5 VOLTS DC BUT AROUND 5 VOLTS DC.I ALSO GOT STATIC OUT OF THE SPEAKER WHICH I COULD CONTROL WITH VOLUME CONTROL.I GOT NO AUDIO FROM SPEAKER. SO I BEGIN MY SEARCH WHAT THE TROUBLE WAS IN THE RADIO.I ALSO FOUND THAT THE 1S5 TUBE I PUT IN WAS VERY MUCH MICROPONIC WHEN TAPP. I CHECKED VOLTAGE ON TUBES AND FOUND THEM CLOSE, ALSO CHECKED THE RESISTANCE ON TUBES AND ALSO FOUND THEM CLOSE. WHILE I WAS CHECKING THE CIRCUITS I GUESS SOMETHING GOT WARMED UP AND THE RADIO STARTED PLAYING.I WAS ABLE TO GO FROM THE LOW END OF BAND TO HIGH AND PICK UP MOST OF THE STATIONS.AFTER PLAYING RADIO FOR A WHILE IT WENT DEAD AND THEN I FOUND THE 1U4, AND THE 1S5 WENT BAD AGAIN.SO I AM WAITING FOR TUBES TO COME IN.I HAVE CHECKED THE CIRCUIT AROUND THE 1S5 TUBE AND REPLACE ALL CAPS, AND RESISTORS THAT DID NOT CHECK GOOD. ALSO DID THE SAME AROUND THE 1U4 TUBE. SO THAT IS WHERE I AM AT THIS TIME, WHEN I HAD THE RADIO PLAYING I LET IT PLAY FOR AROUND 2 HOURS.ANY HELP YOU CAN GIVE ME WOULD BE VERY MUCH APPRECIATED. : : THANKING YOU VERY MUCH AGAIN : RANDALL HORNBACK :SIR EDD: I DO THANK YOU FOR YOUR HELP AND INFORMATION YOU HAVE GIVING ME ON THIS ZENITH HARD CORE RADIO. : :: :: :: :: ::Sir Randall. . . . . :: :: :: ::HEYYYYY . . . your keyboard has done been stuck-ti-cated up on caps . . . . . or else your typing was affected very early in its learning curve by solely, having access to a Teletype. :: :: ::Most humble apologies for the delay, as I was velly velly bizzy . . . along with being snowbound on my operations. :: :: ::In order to cover all, I will just excerpt and fill in afterward with my responses. :: :: :: :: I GOT SOME TUBES AND REPLACED THE BAD ONES THE 3V4, AND I FOUND A VERY WEAK 1S5 :: :: :: ::I was certainly hoping that JUST ONE toobie got knocked out in your series arranged string of tubes. :: :: ::Working with those delicate 1.5 v filament tubes feeds can be touchy /COSTLY ! . . . . Praise be to your benevolent benefactor on your supplication of tube stock ! :: :: :: ::VOLTAGE COMING OFF OF RESISTORS 8,9,10 HOOKED TO WH-BL WIRE GOING TO S-1 TERMINAL 9# AND THEN GET'S SWITCHED THRU IT AND UPWARDS OUT OF TER.8#,THEN THAT 7.5 VDC CONNECTS TO PIN 7# OF 3V4 TUBE AND FLOWS THRU TO COME OUT ITS PIN 1#. :: :: :: ::I am going to just add onto that above info now, and fill in the further and COMPLETE filament path expected to be found in the unit. :: :: ::continuing :: ::. :: . .AND THEN . . . the filament supply path flows out from that 3V4's pin #1 across the bottom to the left to enter pin # 7 of the IR5 then out its pin # 1 to then feed across to the 1U4's pin #7 and then out of its pin #1 and flowing over to the 1S5 pin #7 and out of its pin # 1 which goes to the [BLUE] floating ground buss. :: :: :: :: ::Now take note and confirm that the floating ground bus has to make a connection over to the bottom spst section of your S2 dpst power switch. :: :: ::It then flows down the marked white wire to the pin 2 and connects across to the pin 3 of the S1 AC / Battery changeover switch, with the filament loops final connection being made to the bottom connection into the AC line cords plug. :: :: :: ::I HAD ABOUT 65 VOLTS COMING OFF OF RESISTOR 10 INTO THE WH-BL WIRE GOING TO S-1 ON TERMINAL 9# ALSO ON TER. 8# OF SWITCH,BUT AS I SAID NO FIL VOLTAGE OF ANY KIND ON THE FIL STRING OF TUBES. :: :: :: ::Well as just mentioned that voltage should also be present at the 3V4's pin 7 and with it being SOOOO high, that seems indicative of the rest of the circuitry on thru the 3V4 and the other series tubes being an open circuit and therefore that 65 volts is being a quite high static voltage . . . BECAUSE it is not being loaded down by a full series filament strings presence and thereby loading and reducing it to the proper and expected ~7.5 VDC. :: :: :: :: ::I HAD ABOUT 65 VOLTS COMING OFF OF RESISTOR 10 INTO THE WH-BL WIRE GOING TO S-1 ON TERMINAL 9# ALSO ON TER. 8# OF SWITCH,BUT AS I SAID NO FIL VOLTAGE OF ANY KIND ON THE FIL STRING OF TUBES. :: :: ::EDD IF THIS IS WHERE THE 7.5 VOLTS FOR FILAMENT VOLTAGE IS SUPPOSE TO BE I DONT HAVE IT THERE IT IS ABOUT 65 VOLTS HERE. :: :: ::: ::: NOW EDD, TO :: :: ::COMFIRM THIS IN REGARDS OF THE TWO BLK. WIRES THAT WERE NOT HOOK UP IN THE CIRCUIT. ::THE ONE COMING OFF OF VOLUME CONTROL I PUT IT ON THE BLUE BUSS LINE. :: :: :: ::The schematic confirms that wire as being correct as you installed it, and coming off from the left ::terminal of the volume control. :: :: :: ::AND THE OTHER ONE TO GROUND. :: :: ::I THOUGHT THE ONE BLK. WIRE WAS COMING FROM THE ANTENNA BUT I WAS WROUNG, AND YOU WAS RIGHT.IT WAS A GREEN WIRE AND WHITE WIRE COMING FROM THE ANTENNA.THE GREEN GOING TO THE GRID OF PIN 5# OF THE 1R5 TUBE. :: :: ::AND THE WHITE WIRE GOING TO THE L-2 OSC.COIL. :: :: ::THE OTHER BLK WIRE THAT I PUT TO GROUND WAS COMING FROM THE OFF-ON SWITCH S-2. :: :: :: ::Now that black wire would be the one drawn just above R2 and is conneting between the BLUE buss on the left and the botttom left spst section of the dpst S2 power switch. :: :: :: ::: :::EDD MY BIG QUESTION NOW IS WHERE DID MY FIL. VOLTAGE GO?.WHAT CIRCUIT WOULD BE OPEN NOW BEING I HAVE NO FIL. VOLTAGE?. :: :: ::: :::EDD :: :: :: I GET ABOUT 65 VOLTS DC OFF OF RES 8 AND SHOULD I BE GETTING ABOUT THE SAME VOLTS DC OFF OF COMMON RETURN GROUND? :: :: :: ::Lets confirm if you are metering that voltage properly, as the meter negative should be going to anywhere on the [BLUE] marked up, floating B- ground buss, while the +DCV metering lead should be going to the R8-R9 main B+ supply point, and be expecting the referenced ~ +100 VDC. :: :: ::If your just referenced B+ supply voltages checks out, along with the reduced input passing on thru R9-R10 to the #7 of the 3V4 being as mentioned, lets stop and perform an actual DYNAMIC testing of the filament supply voltage at its inputting point. :: :: ::PROCEDURE: :: :: :: ::Pull the 3V4 to open up the filament supply string, and get yourself a 150 ohm at 1 watt resistor . . . . or else, cobble yourself together some wild . . . parallel-o-series /tandem /shunted /psuedo sequential / random arrangement of loose resistors to be able to acquire that value. :: :: ::That "ree-sistor" then gets connected to the pin 7 connection of the presently removed 3V4, with the resistors other lead getting connected to the [BLUE] B- floating ground buss. :: :: ::That should then "stimulate" a like loading that the sets series filaments would normally be imposing upon the filament supply line, and you should now be reading ~7.5 VDC across that resistor. :: :: ::If that now proves true, that would now indicate an open circuit(s) somewhere in your tube filaments supply present wiring connections, being a most likely fault. :: :: ::Standing by for your findings . . . . . . :: :: :: :: :: ::73's de Edd :: :: :: :: ::

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::::: ::::: ::::: ::::: ::::: ::::: ::::: ::::: :::: SIR EDD: :::: :::: HI EDD, I AM BACK AS YOU TOLD ME TO DO ON THE ZENITH RADIO 4G903.I HOOK-UP ALL THE WIRES, AND RESISTORS, AND CAPS IN THE CIRCUIT AS THE BEST I KNEW HOW.EDD I GOT SOME TUBES AND REPLACED THE BAD ONES THE 3V4, AND I FOUND A VERY WEAK 1S5 ALSO.AFTER REPLACEING THEM I CHECKED OUT THE FIL. CIRCUIT TO SEE IF I HAD THE FIL. VOLTAGE, AND FOUND OUT THAT I DID NOT.I CHECKED THE VOLTAGE COMING OFF OF RESISTORS 8,9,10 HOOKED TO WH-BL WIRE GOING TO S-1 TERMINAL 9# AND THEN GET'S SWITCHED THRU IT AND UPWARDS OUT OF TER.8#,THEN THAT 7.5 VDC CONNECTS TO PIN 7# OF 3V4 TUBE AND FLOWS THRU TO COME OUT ITS PIN 1#. EDD I HAD ABOUT 65 VOLTS COMING OFF OF RESISTOR 10 INTO THE WH-BL WIRE GOING TO S-1 ON TERMINAL 9# ALSO ON TER. 8# OF SWITCH,BUT AS I SAID NO FIL VOLTAGE OF ANY KIND ON THE FIL STRING OF TUBES.EDD IF THIS IS WHERE THE 7.5 VOLTS FOR FILAMENT VOLTAGE IS SUPPOSE TO BE I DONT HAVE IT THERE IT IS ABOUT 65 VOLTS HERE. :::: :::: NOW EDD, TO COMFIRM THIS IN REGARDS OF THE TWO BLK. WIRES THAT WERE NOT HOOK UP IN THE CIRCUIT.THE ONE COMING OFF OF VOLUME CONTROL I PUT IT ON THE BLUE BUSS LINE.AND THE OTHER ONE TO GROUND.I THOUGHT THE ONE BLK. WIRE WAS COMING FROM THE ANTENNA BUT I WAS WROUNG, AND YOU WAS RIGHT.IT WAS A GREEN WIRE AND WHITE WIRE COMING FROM THE ANTENNA.THE GREEN GOING TO THE GRID OF PIN 5# OF THE 1R5 TUBE.AND THE WHITE WIRE GOING TO THE L-2 OSC.COIL.THE OTHER BLK WIRE THAT I PUT TO GROUND WAS COMING FROM THE OFF-ON SWITCH S-2. :::: ::::EDD MY BIG QUESTION NOW IS WHERE DID MY FIL. VOLTAGE GO?.WHAT CIRCUIT WOULD BE OPEN NOW BEING I HAVE NO FIL. VOLTAGE?. :::: ::::EDD I GET ABOUT 65 VOLTS DC OFF OF RES.8 AND SHOULD I BE GETTING ABOUT THE SAME VOLTS DC OFF OF COMMON RETURN GROUND? BECAUSE THAT IS WHAT I AM GETTING THERE. I HAVE GIVEN YOU SOME QUESTIONS THAT I NEED HELP ON, ALL HELP WILL BE APPRECIATED. :::: :::: THANKING YOU :::: RANDALL HORNBACK :::: ::::: ::::: ::::: ::::: :::::Sir Randall. . . . . ::::: ::::: ::::: :::::I will just fill in, just below your concerned statements , such that all will get covered: :::::Plus you can still view the schematic at the bottom, OR, open it up in another window on your browser and then be able to rapidly click/toggle betwixt this text and the schema. ::::: ::::: ::::: ::::: :::::I still have an open circuit and it is the 1 meg. resistor that comes off of transformer T1 on tie-point 4# ::::: ::::: :::::I dont know where it goes. ::::: ::::: :::::This resistor is in the circuit with 3 more 1 meg resistors.They are listed as resistor 2's. ::::: ::::: ::::: :::::OK . . . I am specifically looking at ALL of the commonly shared R2 resistor designators and I see only one unit that would relate to its being associated with the pulling out of a canned electrolytic in times past and its having left a rats nest of unterminated items; inclusive of the expected 4 connections that were initially being made to the filter condenser proper. ::::: ::::: ::::: ::::: :::::The off and on switch works and when on I get about 80 volts from the sel. rect,no sound from the speaker, or buzz. ::::: ::::: ::::: :::::Understood . . . ::::: ::::: ::::: ::::: It also looks like i have no fil. voltage to the tubes.I know that the fil. voltage on tubes are 1 volt, and max is 3 volts. ::::: ::::: :::::Even with the lights off I see no light to the tubes. ::::: ::::: ::::: :::::You are not alone on that aspect. . .in the SEEING of the dull red filament on one of those 1.4 volt tubes even in a pitch dark room AFTER the 'ole eyes finally dilate. ::::: ::::: :::::Worse yet, sometimes, the tube manufacturing process, additionally leaves the top of the tube envelope either darkened or silvered. Hard to circumvent by then viewing from the side mica support discs or up from the bottom. ::::: ::::: ::::: :::::I also put the one black wire from the volume control to the (BLUE)buss line. ::::: ::::: ::::: :::::That looks right . . . . and is also logical that they saw that metal shell of the old electrolytic and its potential four . . .count 'em FOUR . . . twist tab grounds and said . . . Hey lets make that ground to one of those tabs !. ::::: ::::: :::::No problem then, until that can is pulled and the resultant, floating, loose wire just mentioned. ::::: ::::: ::::: :::::The other black wire coming from one end of the antenna i put to ground. ::::: ::::: ::::: :::::Now confirm this for me . . . . as the schema is saying . . .they assigned the top "HOT" RF connection of the loop as being a GREEN wire which goes to the input grid of the 1R5. Understood. ::::: ::::: :::::BUT . . . looking just below the oscillator coil on the route of the "cold" wire downwards from the bottom of the loop antenna . . . they are assigning it a WH . . (ite) color coding, instead of your mentioned black. Physically track down the wire coming down from the bottom of the loop and confirm its color coding and termination point. ::::: ::::: :::::BTW . . . ALL of these R2 designated resitors are being commonly involved in either isolating the AVC feed of the set or with one being used as a leg of a voltage divider for the AVC circuitry. ::::: ::::: :::::Lastly . . . . I agree on the count of them as being 4 items and with my strongest suspicion of the floating ended R2 as being the one on the schematic which goes from your mentioned #4 of the 1st IF transformers secondary and is routed to the right, over to the BLUE buss ( Common floating B minus buss). ::::: ::::: :::::FIO . . the others are: ::::: ::::: :::::Next closest R2's are the two placed in series, the first R2 of which also ties into that same #4 of the 1st IF transformers secondary and then it goes down and ties into another R2 that routes to the right and then up and into term #6 of the secondary of the 2nd IF transformer. That terminal is where the main AVC is derived from. ::::: ::::: :::::The last R2 is deriving a counterpoise bias voltage, that the AVC buss swings against, its being received at terminal #8 of the S1 . . . AC power / Battery power switch. ::::: ::::: ::::: :::::When i would take it from ground i would loose the 80 volts coming from the sel.rect.Then i though i would try to put it also on the (BLUE) buss line. ::::: ::::: :::::When i did i saw the 3v4 tube light up bright and found out i burnt it out. So this is where i am at now, and i need more help in getting this radio up and going. All help appreciated. ::::: ::::: ::::: :::::Now that is the point where I believe that what you did was to have erroneously made a connection between the :::::pin 1 of the 3V4 and the BLUE buss ( Common floating B minus buss). ::::: ::::: :::::That THEN put a full ~7.5 VDC across your 2.8 VDC rated 3V4's filament :::::. . . Toobie go Phhzzzzzzzzzzt . . . and makie a Flashie-Flashie. ::::: ::::: ::::: :::::It shouldn't have affected the others in the series string, as you then shorted out filament power from then even reaching them. ::::: ::::: ::::: ::::: :::::DETAILS: ::::: ::::: :::::Here is a further breakdown of the sets filamental supply flow: ::::: ::::: :::::B+ power initially flows thru the Series resistor string of R8-R9-R10 to get voltage dropped and finally come out and flow outwards, to the right as designated wire WH-BL and terminate at S1 terminal 9 and then get switched thru it and upwards out of terminal #8. ::::: ::::: :::::That ~7.5 VDC connects to pin 7 of the 3V4 and flows thru to come out its pin 1. ::::: ::::: :::::That flow is then over to the left to connect to 1R5's pin 7, with the additional picking up of some filtering / decoupling via your 200 mike down on the Green buss. ::::: ::::: :::::After passing thru the 1R5 the path is out of its pin 1 and into the 1U4 pin 7 and then out its pin 1, with the further flow then being over to the right and then up, to come in pin 7 of the 1S5, flow thru and exit via pin 1 :::::and then FINALLY . . . whewwwwww . . its getting grounded via the BLUE buss. ::::: ::::: :::::Therewith . . . all of your tubes filaments are being series fed from ~7.5 VDC and additionally maintaining the proper circuitry design tenet of having the RF converter tubes filament being well bypassed/ decoupled along with the audio preamp and detector tube having its filament being as close to ground as is possible. ::::: ::::: ::::: :::::Until such time as you have a another 3V4, in the interim, you could pre evaluate the filament supply by having the old 3V4 in circuit . . .(open filament . . . and STILL not feeling to well inside ) . . . but then you place a 150 ohm 1/2 --> 1 watt resistor from pin 7 of the 3V4 to the floating common B- buss (BLUE). ::::: ::::: :::::Now, on power up, it should be reading ~ 7.5 VDC across its simulated filament string load, thereby signifying that you are in order on the supply level, once you get the next 3V4 to put in circuit. ::::: ::::: ::::: ::::: :::::Check out the sets wiring and . . . . .Talka to me . . . . mamma mia ! ::::: ::::: ::::: ::::: ::::: ::::: :::::73's de Edd ::::: ::::: ::::: ::::: :::::

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::::::: ::::::: ::::::: ::::::: ::::::: ::::::: ::::::: :::::: :::::: Sir Edd: :::::: :::::: Getting back with you on the Zenith radio that had the filter condenser taken out and not put back in the circuit. The radio was a Zenith model 4G903 Chassis 4F40. I used 4 electrolyic caps to replace the one 4 section cap.I think i got them wired back in as you pointed out to me.I checked out the tubes and found them good, i still have an open circuit and it is the 1 meg. resistor that comes off of transformer T1 on tie-point 4# i dont know where it goes.This resistor is in the circuit with 3 more 1 meg resistors.They are listed as resistor 2's. The off and on switch works and when on i get about 80 volts from the sel. rect.no sound from the speaker, or buzz. It also looks like i have no fil. voltage to the tubes.I know that the fil. voltage on tubes are 1 volt, and max is 3 volts. Even with the lights off i see no light to the tubes. I also put the one black wire from the volume control to the (BLUE)buss line.The other black wire coming from one end of the antenna i put to ground.When i would take it from ground i would loose the 80 volts coming from the sel.rect.Then i though i would try to put it also on the (BLUE) buss line. When i did i saw the 3v4 tube light up bright and found out i burnt it out. So this is where i am at now, and i need more help in getting this radio up and going. All help appreciated. :::::: :::::: Thanking You :::::: Randall Hornback ::::::: ::::::: ::::::: ::::::: ::::::: :::::::Sir Roger. . . . . ::::::: ::::::: :::::::The one with the old trade schools silly scope kit . . . ? ::::::: ::::::: :::::::Considering having wiring the multiple caps to a terminal strip and using their common grounding to the Floating B negative portion of the set . . . .(Heavy [BLUE] buss) . . . as Cap C17 holds it above ground for DC potential but AC and RF will couple thru via C17. ::::::: ::::::: ::::::: ::::::: :::::::I made a clarified mark up of that area of concern in which case, you may find that the missing canned filter had R8 . .R9 . .and R10 resistors intertwined and wired between the terminals and have left along with the filter. ::::::: ::::::: :::::::Possibly R6 up above may be gone also. ::::::: ::::::: :::::::Sounds like you may have already pinpointed all connections, but I color highlighted each buss also. ::::::: ::::::: :::::::Don't know if that incoming 140 0hms input from the Selenium rectumfire is there also ? ::::::: ::::::: ::::::: ::::::: ::::::: :::::::From your last supplied info, looks like of those two mystery black wires: ::::::: ::::::: :::::::1 . . .One of them must have been the one which WAS going to the common ground trminal on the canned filter which we NO longer have. ::::::: ::::::: :::::::2 . . .The other one would have went up to the low side of the vol-you-me control which I have assigned as being tied into the [BLUE] buss. ::::::: ::::::: ::::::: :::::::Hope this info might "heps" you out. ::::::: ::::::: ::::::: ::::::: :::::::73's de Edd ::::::: ::::::: ::::::: ::::::: :::::::

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::::::::::::I need help in finding a electrolytic capacitor for a Zenith radio model 4G903 chassis 4F40. The part no. on the capacitor is 22-1741. If you have one or know where i can find one please let me know.
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:::::::::::: Thanking You
:::::::::::: Randall Hornback
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:::::::::::That is the multisection filter cap and it is unlikely you wll be able to find one. You will need to replace it with 4 individual caps which are rated at 60, 20 40uf at 150 volts and 200uf at 10 volts.
:::::::::::Johnnysan-
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:::::::::: Hi Johnnysan, a big thank you for the information you gave my way on the multisection filter cap.
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::::::::::The other problem i have is that who ever had the radio before me took out the filter cap and did not put it back in the radio oe leave it with the radio.And they did not leave a schematic on how to wire the cap back in.I have a schematic on the radio but having trouble how to hook up wires, and caps, and resistors if i use the 4 individual caps. And does the ground to these caps go to ground or do they have to be above the ground?.I need all the help you can give me, and will appreciate it very much
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:::::::::: Thanking You
:::::::::: Randall Hornback
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:::::::::Hi Randall,
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:::::::::How I appreciate your situation. It is no fun when a part has been removed and you are left to guess how the wiring to the part was arranged. You will need to carefully examine the schematic and hopefully you have a parts list to guide you. Look very carefully for the "GROUND" Symbol which looks like an arrow pointing straight down. The "arrow" most commonly is made up of 3 rows of dashed lines pointing down. Sometimes a "trapezoid" symbol is specifically used to denote the Chassis Ground.
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:::::::::"Floating" grounds on filter capacitors are also very common. Your set may even contain a mix of chassis and floating grounds. Any where that your schematic indicates chassis grounds, those electrolytics should be chassis grounded. And if the schematic shows no "ground" symbol on any given filter cap negative lead DO NOT ground it to your chassis!
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:::::::::Above all, be very careful not to wire a filter cap backwards. The negative lead in virtually all cases is the "ground" lead - the correct polarity must be observed or the Electrolytic Capacitor may blow apart.
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:::::::: Hi Daniel,
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::::::::I do appreciate the load of information you sent my way.I will do my best to check out the schematic and study where the wires,caps,resistors go to the 4 individual filter caps i will used to replace the filter cap that was taken out of the circuit.
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::::::::If i am looking at the schematic right it has both grounds, the floating ground and the ground ground.The filter was hook to the floating ground between cap 12 .047 and cap 17 .05 this is where i will put the neg.leads of the 4 individual caps i will be useing here.
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::::::::Daniel i have 2 black wires coming to where the filter was.One wire comes from the vol. control on outside leg, the other black wire comes from the end of antenna where will these wires hook up at?. Will appreciate any and all help.
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:::::::: Thanking You
:::::::: Randall Hornback
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