I found a Pilot One AA-410 while cleaning for my grandfather. The tubes glow and it makes music, but doesn't sound right. I have documented and cut caps and will test the tubes.
"dc dry electrolytic"(100mfd) and "Marbelite Impregnated"(0.1;0.047mfd) are before my time.
What types of caps do I replace this with and what else should I replace? Thanks!
"dc dry electrolytic"(100mfd) and "Marbelite Impregnated"(0.1;0.047mfd) are before my time.
What types of caps do I replace this with and what else should I replace? Thanks!
Change all the electrolytics and change the coupling-caps with MKPs. Any modern brand will do the job.
If there is a selenium rectifier it will be good to change it with modern silicon (maybe1N4007) but then you must do some resistance in series with the rect. to keep the voltage down (i hope you understand my Germlish)
Perhaps it will be helpfull to post some pictures and a schematic.
Good luck,
Hilmar
If there is a selenium rectifier it will be good to change it with modern silicon (maybe1N4007) but then you must do some resistance in series with the rect. to keep the voltage down (i hope you understand my Germlish)
Perhaps it will be helpfull to post some pictures and a schematic.
Good luck,
Hilmar
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100mfd is the old way of saying 100uF - an electrolytic so replace with an electrolytic.
0.047mfd is 47nF - probably impregnated paper dielectric, so replace with a modern film dielectric cap.
You could try debugging (i.e. find the fault) before you attempt to fix it. Check DC values, for a start.
0.047mfd is 47nF - probably impregnated paper dielectric, so replace with a modern film dielectric cap.
You could try debugging (i.e. find the fault) before you attempt to fix it. Check DC values, for a start.
A good reason to replace all the power supply and coupling caps also is that you risk (failure) any or all the transformers if you don't.
Best test for tubes is in a properly functioning circuit. Cleaning all tube pins and sockets, switches etc. can help also. Testing resistors can't hurt either as if anything they usually measure high (if bad) and they can usually be tested in circuit with tubes out.
Best test for tubes is in a properly functioning circuit. Cleaning all tube pins and sockets, switches etc. can help also. Testing resistors can't hurt either as if anything they usually measure high (if bad) and they can usually be tested in circuit with tubes out.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Thanks. It uses a 5Y3GT rectifier tube.
The big green components (middle and far right) are resistors?
I plan to replace all 4 caps. The fatty labeled "E4" is the 100mfd. It should be mkp as well? This is my first tube amp and I don't have schematics... so debugging = replace caps and try it.
Thanks again
A little late to the party, but I recently rebuilt my UL 6L6 AA-410A (slightly different then the pentode 6L6 AA-410) using the following capacitor values:
C1a - left at 20uF
C1b - upped to 80uF
C1c - upped to 40uF
C1d - upped to 40uF + 33uF
C2 - upped to 680uF
Added 120uF/250v across R2
I replaced C4/C5 with Sprague Orange Drops and C3 with a Multicap PPFX. All resistors except R10 were replaced. And I added 1k resistors to pins 4 and 5 of the output tubes.
All component numbers are taken from the AA-410 SAMS schematic as there doesn't seem to be an AA-410A schematic floating around.
I also added a CL-80 at the ac power input to the power transformer to cut the voltage a bit. I ended up with 376v out from the 5Y3 vs 385v on the SAMS schematic.
All I can say ... I'm very happy with the results!
C1a - left at 20uF
C1b - upped to 80uF
C1c - upped to 40uF
C1d - upped to 40uF + 33uF
C2 - upped to 680uF
Added 120uF/250v across R2
I replaced C4/C5 with Sprague Orange Drops and C3 with a Multicap PPFX. All resistors except R10 were replaced. And I added 1k resistors to pins 4 and 5 of the output tubes.
All component numbers are taken from the AA-410 SAMS schematic as there doesn't seem to be an AA-410A schematic floating around.
I also added a CL-80 at the ac power input to the power transformer to cut the voltage a bit. I ended up with 376v out from the 5Y3 vs 385v on the SAMS schematic.
All I can say ... I'm very happy with the results!
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