Be sure electrolytic caps have at least 150 volt rating and are installed in proper polarity.
Here is a schematic:
http://www.nostalgiaair.org/PagesByModel/394/M0013394.pdf
Replace cap #39, .04 mfd, from plate, pin #2, of your 35A5 to B-. If this cap shorts your radio will draw excessive current.
If you blow out any tube filament in this radio all tubes will no longer be lit. Most likely if a tube is damaged it will be 35Z3.
Test your radio with a 60 watt lamp in series with the AC line. If something is shorted the lamp will light bright. This acts as a fuse allowing you to unplug the radio, saving tubes.
Norm
:There is a short in the radio. I have changed all the "caps" and rubber wires. changed the electrolytic condensers. changed the resistor(89-53)that was burned out at the center tap going to the plate of the 35Z3 tube. changed the pilot light.I changed the tubes.when I touch the resistor center tap(89-53) to the plate of the 35Z3 tube it blows out the pilot light and all but two tubes. the speaker is in very bad shape. I know a little but not enough about radios. any help will be welcome. Callie Miller
Callie
I just somehow believe you have your wiring messed up. Sounds like you have shorted your filament circuit, could be after the point where the last tube blows. The total line voltage is being applied and zap. It's like trying to light a 36 volt lamp with 117 volts. Are the resistors correct value. How many connections to plate of 35Z3. It's gotta be something simple. Recheck wiring.
Hi Callie
:
: Be sure electrolytic caps have at least 150 volt rating and are installed in proper polarity.
:
: Here is a schematic:
:
:http://www.nostalgiaair.org/PagesByModel/394/M0013394.pdf
:
: Replace cap #39, .04 mfd, from plate, pin #2, of your 35A5 to B-. If this cap shorts your radio will draw excessive current.
:
: If you blow out any tube filament in this radio all tubes will no longer be lit. Most likely if a tube is damaged it will be 35Z3.
:
: Test your radio with a 60 watt lamp in series with the AC line. If something is shorted the lamp will light bright. This acts as a fuse allowing you to unplug the radio, saving tubes.
:
:Norm
:
::There is a short in the radio. I have changed all the "caps" and rubber wires. changed the electrolytic condensers. changed the resistor(89-53)that was burned out at the center tap going to the plate of the 35Z3 tube. changed the pilot light.I changed the tubes.when I touch the resistor center tap(89-53) to the plate of the 35Z3 tube it blows out the pilot light and all but two tubes. the speaker is in very bad shape. I know a little but not enough about radios. any help will be welcome. Callie Miller
Now, on to connecting to the plate of the 35Z3. Make ABSOLUTELY SURE that when you read the circuit diagram that you remember that wires that cross WITHOUT a dot are NOT connected, and wires that cross WITH a dot ARE connected. The return line to the AC plug crosses the wire that leads from the ballast resistor to the plate, as shown in the circuit diagram. If this wire was to actually be connected to the plate of the 35Z3 tube, and you connected the pilot to the plate, you would blow both the pilot lamp and the resistor. If you have altered any of the wiring in the radio, be sure to consult the diagram carefully and keep the above in mind. I can see how if the circuit diagram was interpreted improperly, much trouble would result. There are many wires on that diagram that cross in critical places, and if they were actually connected at these places, they would blow up the radio. I can see how much confusion would result even when looking at the connections made by the electrolytics. Zoom in on this area or any area of the radio that you have worked on, and make sure that all is well.
....And as I said before, if the pilot and the resistor are blown, NONE of the tubes should light. The filaments are strung in series. If most of the tubes go out and some are still lit, something is wrong. If you pull one tube, ALL, including the pilot lamp, should go out. Check the entire filament wiring. Make sure, starting at the ballast resistor, that the wiring is as follows: Wiring comes in to ballast resistor from AC cord. Center tap of ballast goes to plate of 35Z3 tube. Pilot lamp connects between these two points. NOTHING, ABSOLUTELY NOTHING else connects to either the plate of the 35Z3 tube or to the center tap of the resistor. The resistor continues on to its other side, which continues on, through a wire, to either pin 1 or 8 of the 35Z3 tube. With loctal tubes, with few exceptions, the filament pins are 1 and 8. That said, the filament wiring leaves the 35Z3 tube with the other remaining filament pin (either 1 or 8, opposite of that used previously). It continues on to the next tube, either pin 1 or 8, and leaves the other pin to the next, and the next, and so on. NOTHING else should be connected to any of these pins. The wiring should enter the filament of a tube through one pin, and then leave the other, and continue on to the next. The last tube will be XXD, also known as 14AF7. At this tube, the wiring should enter one of the filament pins. The other filament pin will have a wire running to the AC switch, which will continue on to the AC cord. The pin terminal that connects to the wire that runs to the AC switch may have other items tied to it. This pin connects to the AC return, and at this point the AC return also serves as B- current that supplies all of the tubes' plates and grids and cathodes, etc. Any other connections to any of the other filament pins, other than those mentioned above, is unacceptable, and if any are found, they should be corrected, or ask us what to do.
Thomas
Callie Miller
Thomas
I looked at the circuit and have two theories to this issue.
My first theory is that there is a short to ground or to hot (depending on the polarity of the plug), from the far end of the filament of either the 35A5 or possibly the 7C6 tube. This would explain why to stay lit and the others don't
My Second theory is that someone re-wired the fillaments of this radio at some time for 32 Volt (Farm) operation, probably with an external B Power Supply that was vibrator operated, or using a 90 volt battery for B+. The reason I came up with this theory is that if you re-wire the 35 Volt tubes in PARALLEL, and the other tubes in Series (7+7+7+14=35), you can run 35V tubes off of 32V acceptably in most cases, and it would also explain why two of the 35V tubes stay lit.
:Do they get brighter or dimmer??? This is very odd. Sounds like some exciting wiring trouble. The plate should not be connected to anything (except the resistor when you connect it), and as I said, the filament string should continue on from the resistor to the other tubes, one at a time. No other connections should be made in the string. If the resistor/bulb blow out, all of the tubes should go out. The 35Z3, which is the start of the string, receives its power from the resistor, and the string does not end until the 14 whatever it was tube. If the resistor and bulb blow, power will be cut off to the 35Z3, and all of the tubes will go out. Since the 35Z3 and 35A5 stay lit, something is seriously wired incorrectly. Some of these tubes must be burning excessively bright or dim or something, as this is just not right. Check the wiring of the filaments. Make sure it is just like a Christmas light set....one bulb to the next to the next...the kind where when you remove one bulb, they all go out.
:
:Thomas
T.
:Thomas,
:
:I looked at the circuit and have two theories to this issue.
:
:My first theory is that there is a short to ground or to hot (depending on the polarity of the plug), from the far end of the filament of either the 35A5 or possibly the 7C6 tube. This would explain why to stay lit and the others don't
:
:My Second theory is that someone re-wired the fillaments of this radio at some time for 32 Volt (Farm) operation, probably with an external B Power Supply that was vibrator operated, or using a 90 volt battery for B+. The reason I came up with this theory is that if you re-wire the 35 Volt tubes in PARALLEL, and the other tubes in Series (7+7+7+14=35), you can run 35V tubes off of 32V acceptably in most cases, and it would also explain why two of the 35V tubes stay lit.
:
::Do they get brighter or dimmer??? This is very odd. Sounds like some exciting wiring trouble. The plate should not be connected to anything (except the resistor when you connect it), and as I said, the filament string should continue on from the resistor to the other tubes, one at a time. No other connections should be made in the string. If the resistor/bulb blow out, all of the tubes should go out. The 35Z3, which is the start of the string, receives its power from the resistor, and the string does not end until the 14 whatever it was tube. If the resistor and bulb blow, power will be cut off to the 35Z3, and all of the tubes will go out. Since the 35Z3 and 35A5 stay lit, something is seriously wired incorrectly. Some of these tubes must be burning excessively bright or dim or something, as this is just not right. Check the wiring of the filaments. Make sure it is just like a Christmas light set....one bulb to the next to the next...the kind where when you remove one bulb, they all go out.
::
::Thomas
T D,
The lights from these two tubes are normal. When I put a new pilot lite in and turn on the radio all the filiments in the tubes are on. If I take the plate wire from the 35Z3 tube and touch the center tap of the resister(ballist) The pilot lite will blow. I do have a setup of a 60 watt bulb in series so that I won't blow The pilot lite eveytime. Haven't had much time lately to look at the radio but have printed all the infomation that I have received.
Callie Miller
Callie Miller
Thomas
::Do they get brighter or dimmer??? This is very odd. Sounds like some exciting wiring trouble. The plate should not be connected to anything (except the resistor when you connect it), and as I said, the filament string should continue on from the resistor to the other tubes, one at a time. No other connections should be made in the string. If the resistor/bulb blow out, all of the tubes should go out. The 35Z3, which is the start of the string, receives its power from the resistor, and the string does not end until the 14 whatever it was tube. If the resistor and bulb blow, power will be cut off to the 35Z3, and all of the tubes will go out. Since the 35Z3 and 35A5 stay lit, something is seriously wired incorrectly. Some of these tubes must be burning excessively bright or dim or something, as this is just not right. Check the wiring of the filaments. Make sure it is just like a Christmas light set....one bulb to the next to the next...the kind where when you remove one bulb, they all go out.
::
::Thomas
:
:T D,
:The lights from these two tubes are normal. When I put a new pilot lite in and turn on the radio all the filiments in the tubes are on. If I take the plate wire from the 35Z3 tube and touch the center tap of the resister(ballist) The pilot lite will blow. I do have a setup of a 60 watt bulb in series so that I won't blow The pilot lite eveytime. Haven't had much time lately to look at the radio but have printed all the infomation that I have received.
:
: Callie Miller
:
: Callie Miller
Could the Cathode of the 35A5 or the cathode of the of the 7C6 be shorted somehow? It seems that if the other tubes go out, the problem may be further down the line, due to the fact that the 35A5 also stays lit.
Another test might be to remove the 35A5 and 7C6, and see if the filament pin that leads to the 7C6 from the 35A5 is shorted to B- by using an ohmmeter. Also, check to make sure it is connected to the 7C6. If it is not, and instead just goes to B- (or A-), it proves my "32 volt rewiring theory".
Stephen
:Well, then I'm baffled. I don't understand it at all. I do not understand how some of the tubes go out and the rest stay lit. If you pull out a tube, they should all go out. According to the circuit diagram, your chassis is not directly connected to the return line (B-), so even if the cathode of the 35Z3 was shorted to the chassis, this would not tend to blow the pilot, unless the chassis condenser is shorted as well. I cannot come up with any more ideas. I'd have to see the set in person. All I can say is to follow the diagram exactly and make sure that the radio is wired exactly as the diagram shows. Make sure that you are reading the tube sockets properly. Remember that when you are looking at them from under the chassis that pin 1 is to the right of the keyway when it is facing down, and the pin numbers go higher as you go clockwise around the socket. If there was some confusion here, and you mistook a different pin for the plate pin, that is not used by the 35Z3, but may have been used as a terminal junction, this may blow things up.
:
:Thomas
:
:::Do they get brighter or dimmer??? This is very odd. Sounds like some exciting wiring trouble. The plate should not be connected to anything (except the resistor when you connect it), and as I said, the filament string should continue on from the resistor to the other tubes, one at a time. No other connections should be made in the string. If the resistor/bulb blow out, all of the tubes should go out. The 35Z3, which is the start of the string, receives its power from the resistor, and the string does not end until the 14 whatever it was tube. If the resistor and bulb blow, power will be cut off to the 35Z3, and all of the tubes will go out. Since the 35Z3 and 35A5 stay lit, something is seriously wired incorrectly. Some of these tubes must be burning excessively bright or dim or something, as this is just not right. Check the wiring of the filaments. Make sure it is just like a Christmas light set....one bulb to the next to the next...the kind where when you remove one bulb, they all go out.
:::
:::Thomas
::
::T D,
::The lights from these two tubes are normal. When I put a new pilot lite in and turn on the radio all the filiments in the tubes are on. If I take the plate wire from the 35Z3 tube and touch the center tap of the resister(ballist) The pilot lite will blow. I do have a setup of a 60 watt bulb in series so that I won't blow The pilot lite eveytime. Haven't had much time lately to look at the radio but have printed all the infomation that I have received.
::
:: Callie Miller
::
:: Callie Miller