I'm not sure if I got my posts mixed up between the two 530 amp posts. So if it doesn't make sense, ignore it.
That's good that you replaced all of the paper caps, but when doing so, also include new filter caps no matter what they read. Just in case you don't know, it's rare, but sometimes the caps in cans have internal shorts/leakage from one cap to the other. Be sure to jumper all caps that aren't being tested to ground when testing them for both capacitance and leakage. And again, if the cap is rated for 450v, then the tester must put 450 volts onto the capacitor. While testing the leakage, measure the voltage from the cap lead to ground. With a decent tester, they normally go to a voltage higher than the rated voltage. But like said, just replace it anyway.
On 8/23/2025 7:52 AM, M De Simone via Jukebox-list wrote:
Tony, I didn’t test the paper capacitors, I just replaced them all. I tested the multi section can capacitors with an esr tester and C34 tested like a new capacitor but C35 was bad. I will change it soon anyway but for testing purposes I did not think it would be an issue, the amplifier has no hum whatsoever. Mauro
Sent from my iPhone
On Aug 23, 2025, at 6:33 AM, Tony Miklos via Jukebox-list jukebox-list@lists.netlojix.com wrote:
On 8/22/2025 5:38 PM, Tony Miklos wrote:
On 8/22/2025 4:43 PM, M De Simone via Jukebox-list wrote: Another amplifier issue! A W530 that has been recapped and any out of tolerance resistors replaced. Tubes all check good. I’m getting about 50% to 60% of gain it should have. I’ve run some tests and found the DC voltages are all low at the tube pins by about 20%. I’ve checked anything I could think of but no luck. Looking for advice as Im not well versed enough to understand where the voltages come from. Can anyone tell me what exactly the 4 section electrolytic capacitor C34 does? I’m suspecting it, as I replaced C35 (the other one) but C34 tested perfect so I left it in, just for now. Any help appreciated, Mauro
Did you test the capacitor up to the rated voltage value? (? 350v 400v 450v) Or did you use one of those handheld DMM ones? If you don't have a schematic and can follow it, well IDK. I've done close to 50 of them and their close cousins, even with proper B+ voltages many had low output. It was the AVC circuit. To do it right, you should replace that one cap that you skipped. I think, but don't know, did the small value (.001 - .5) caps back then sometimes leak a little from new? I'd really like to know. Within specs, but a little leaky.
-- Tony Miklos Tony's Jukebox Repair
Jukebox-list mailing list -- jukebox-list@lists.netlojix.com To unsubscribe send an email to jukebox-list-leave@lists.netlojix.com %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s Searchable Archives: http://jukebox.markmail.org/
Jukebox-list mailing list -- jukebox-list@lists.netlojix.com To unsubscribe send an email to jukebox-list-leave@lists.netlojix.com %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s Searchable Archives: http://jukebox.markmail.org/