I know there has been previous discussions on this issue, but I can't find anyt past discussions to solve my current problem. Finishing up an Admiral 47-J55, the pilot light socket was disconnected and removed and the tap wires taped together.(Now I know why)I rewired a new pilot socket and used a #47 bulb and it blows out when I power up, even if I bring up gradually with a variac. I pulled the tap wires apart, naturally the 35Z5 got bright because of the lack of a shunt, but the tap to pin 5 and pin 3 voltage is at 110, the tap wire to pin 2 (same as the power input) is at 122. Almost seems like there's a resistor missing in the circuit, but none indicated on the schematic.

When the taps are connected, they read 122 volts at the pilot light socket. This seems like a standard tap circuit from what I see on other AA5 schematics. Anyone have a solution? I running out of #47 bulbs using the "trial and error" method!

Thanks,

Allan

.....Very strange..... You read 110 at pin 3, and 122 at pin 2? Well, that indicates a 12 volt drop, which is acceptable with no pilot lamp in place, but it should be a bit lower with the pilot lamp in place--6.3 volts. All sounds normal at this point. Make sure that there are no shorts in the power supply, and make sure that the section of filament between pins 2 and 3 is good, and that the tube and socket are making good connection. You explained the wiring a bit, but it wasn't super clear, so I'll run through how the wiring should be. Follow this exactly: line cord should go to pin 2. Pilot lamp should go across 2 and 3. A wire should go from 3 to 5. You can substitute a 50 ohm 1/4 watt resistor for the wire to act as a buffer and a safety fuse. B+ should be taken off of pin 8. Be sure that the rectifier is good, and that there are no internal shorts. If you decide to eliminate the pilot lamp, you must shunt across pins 2 and 3 of the rectifier, or else that section of filament will be ruined if left wired as originally wired.

If the radio is wired as it should be, and all is working well, then you should have no troubles. Be sure that the pilot lamp socket's clip is insulated from the socket. If it isn't, and the chassis is connected directly to the line, you can blow both the pilot lamp and the 35Z5, and if the pilot lamp wires are reversed, you can also blow a fuse.

If you absolutely cannot find the trouble, you can shunt the pilot lamp with two 6.8 to 7.0 volt zener diodes wired back-to-back. However, I strongly believe that there is a problem, and that the pilot lamp will function normally once the problem is solved.

T.

Thomas:
Thanks for the item by item description of the wiring layout. Looks like I had a bad connection with the pilot lamp connection to pin 3. This pin also carries a .05 capacitor running to ground, and the pilot lamp wire was grounding. I replaced the capacitor and re-soldered the pilot lamp wire. Works great now! Thanks for your help.

Allan

:.....Very strange..... You read 110 at pin 3, and 122 at pin 2? Well, that indicates a 12 volt drop, which is acceptable with no pilot lamp in place, but it should be a bit lower with the pilot lamp in place--6.3 volts. All sounds normal at this point. Make sure that there are no shorts in the power supply, and make sure that the section of filament between pins 2 and 3 is good, and that the tube and socket are making good connection. You explained the wiring a bit, but it wasn't super clear, so I'll run through how the wiring should be. Follow this exactly: line cord should go to pin 2. Pilot lamp should go across 2 and 3. A wire should go from 3 to 5. You can substitute a 50 ohm 1/4 watt resistor for the wire to act as a buffer and a safety fuse. B+ should be taken off of pin 8. Be sure that the rectifier is good, and that there are no internal shorts. If you decide to eliminate the pilot lamp, you must shunt across pins 2 and 3 of the rectifier, or else that section of filament will be ruined if left wired as originally wired.
:
:If the radio is wired as it should be, and all is working well, then you should have no troubles. Be sure that the pilot lamp socket's clip is insulated from the socket. If it isn't, and the chassis is connected directly to the line, you can blow both the pilot lamp and the 35Z5, and if the pilot lamp wires are reversed, you can also blow a fuse.
:
:If you absolutely cannot find the trouble, you can shunt the pilot lamp with two 6.8 to 7.0 volt zener diodes wired back-to-back. However, I strongly believe that there is a problem, and that the pilot lamp will function normally once the problem is solved.
:
:T.

Is your replacement pilot light socket electrically isolated from the mounting point or clip? I can't find a schematic for your set specifically, but if one side of the socket was 'grounding out' to the other side of the line connection, I can see where that might happen (although I would think that the filament of the 35Z5 would be toast also).

:I know there has been previous discussions on this issue, but I can't find anyt past discussions to solve my current problem. Finishing up an Admiral 47-J55, the pilot light socket was disconnected and removed and the tap wires taped together.(Now I know why)I rewired a new pilot socket and used a #47 bulb and it blows out when I power up, even if I bring up gradually with a variac. I pulled the tap wires apart, naturally the 35Z5 got bright because of the lack of a shunt, but the tap to pin 5 and pin 3 voltage is at 110, the tap wire to pin 2 (same as the power input) is at 122. Almost seems like there's a resistor missing in the circuit, but none indicated on the schematic.
:
:When the taps are connected, they read 122 volts at the pilot light socket. This seems like a standard tap circuit from what I see on other AA5 schematics. Anyone have a solution? I running out of #47 bulbs using the "trial and error" method!
:
:Thanks,
:
:Allan