dbonin

Re: [BUILD] 1176 Rev F/G - new board, new transformer!
« Reply #460 on: August 03, 2020, 07:39:38 AM »
Hey,

So I've had a pre 2016 rev f/g for years now, working great. All of a sudden, a few years ago, a 60 cycle hum appeared. The hum occurs when the unit is on with no input or output connected (using a 0db 1khz sine wave with scope and just a scope). I can also hear it when its hooked up to a signal chain.  I have been all through the unit many times and re-flowed just about everything a few times at this point, dc voltage rails are good. I can't seem to track down this hum.... Nothing appears to be cracked nor do any joints seem to have come apart. Any information regarding troubleshooting this would be a great help, thanks!
Usually bad AC power filter caps, but the unit is not that old...  still, I'd start there.
Stand off to the side of the unit, out of the line of fire.  Flip the ON switch...  "Watch for flames and sniff for smoke."


 

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