Technics SA-404 running hot!

alphaone

Member
2013-02-03 10:52 pm
I have a Technics SA-404 receiver and I love it BUT the power transformer gets very hot after 30 minutes of operation at 1/4 volume. I need help as to what to do. My first thought was to put a cooling fan on it but I don't want to bandage it and ignore the cause of the problem. Besides the heat I get a slight odor of "burned electronics". I know that should be a red flag. How do I go about diagnosing the issue? I have a service manual and I 'm handy with a VOM. My thought is to find a replacement power transformer but I would like some input from a brain more full than mine please.:eek:
 
The first step is to find where the power is going...likely places include:

1. too much quiescent current in the audio power amps
2. supersonic oscillation in the audio power amps (once again causing excess power draw)
3. shorted turn(s) in the power transformer

Given that everything still works (?), you should be able to feel and smell your way around the amp to see where the power is going. That should be the single biggest hint. Of course, you could isolate each major load, but I'm trying to suggest a reasonable shortcut, which might be less work...



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