Very frustrating story here... spent over two weeks restoring and upgrading a pair of AM-1027s for a customer, with mods to make them suitable for home hi-fi use.
One of the units had leaked potting all over the chassis. The leakage came from the choke. However, the choke and power transformer both checked out okay at the time. First ohmmeter check then, rebuild the amplifiers and test.
The amplifiers have both been operational for over a week, powered on several times a day during testing and refining of the audio stages. Then they ran for two days into a pair of speakers with music program for several hours each day.
I finally had the customer come to pick them up, having worked out all problems with the amps and seeing that they seemed reliable.
This morning the customer arrives, and I flip on the power for the amps, but when I play the program material, only the right channel is working. I notice the tubes are not lit on the left AM-1027, the one that I'd cleaned up the potting gunk mess on a month earlier. Turns out the 2A fuse had blown. So I replaced it, but it blew again a few seconds after power up. Having found a bad rectifier earlier, I next thought maybe the rectifier was failing, so I pulled it out of the socket, put in a new fuse and watched it blow again in a few seconds.
Disconnected everything from the transformer. Primary reads about 2.5 ohms. Still blows the fuse and draws about 400W off the line when applying full line voltage to the primary with nothing connected to the secondaries.
Looking for a good, working replacement that has not undergone years of running into shorting electrolytics like this one has. Does anyone have a lead?
One of the units had leaked potting all over the chassis. The leakage came from the choke. However, the choke and power transformer both checked out okay at the time. First ohmmeter check then, rebuild the amplifiers and test.
The amplifiers have both been operational for over a week, powered on several times a day during testing and refining of the audio stages. Then they ran for two days into a pair of speakers with music program for several hours each day.
I finally had the customer come to pick them up, having worked out all problems with the amps and seeing that they seemed reliable.
This morning the customer arrives, and I flip on the power for the amps, but when I play the program material, only the right channel is working. I notice the tubes are not lit on the left AM-1027, the one that I'd cleaned up the potting gunk mess on a month earlier. Turns out the 2A fuse had blown. So I replaced it, but it blew again a few seconds after power up. Having found a bad rectifier earlier, I next thought maybe the rectifier was failing, so I pulled it out of the socket, put in a new fuse and watched it blow again in a few seconds.
Disconnected everything from the transformer. Primary reads about 2.5 ohms. Still blows the fuse and draws about 400W off the line when applying full line voltage to the primary with nothing connected to the secondaries.
Looking for a good, working replacement that has not undergone years of running into shorting electrolytics like this one has. Does anyone have a lead?
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