Hi All, So, I'm trying to bring this amp back to life. Initially it blew both fuses between the transformer and the rectifier diodes. After replacing the fuses and bringing the voltage up slowly (variac + lightbulb limiter) I was able to get some sound from a line in source. However, when I tried to increase the V the amp started sucking current like there was no tomorrow. All transistors read good on a transistor checker.After some checking I found that R78 was burning up. I can't figure out what is causing R78 to burn. I replaced a number of carbon comp resistors, the worst out of spec was R78, which was going open at 200 ohms. Every single diode reads good. Lifting the cathode leg of D17 eliminates the short. The electrolytes all check out good. I put a 9vdc charge on the filter caps which came back at about 7.5vdc.
I was going to throw in the towel on this amp, but it just bugs me that I can't figure it out. All insights appreciated. thanks Drewv
Attached is all the info on this amp. A few of the values and/or part numbers are different than what I'm looking at, but nothing major.
I was going to throw in the towel on this amp, but it just bugs me that I can't figure it out. All insights appreciated. thanks Drewv
Attached is all the info on this amp. A few of the values and/or part numbers are different than what I'm looking at, but nothing major.