# Mc440 not working powerguard always on



## Jakec10 (Oct 2, 2019)

Hi guys, I have read all the posts regarding the McIntosh mc440 amp and the problems with them but haven't been able to find a solution for this problem, the amp turns on, both fans turn on at what seems a medium/high speed but the powerguard led comes on and it doesn't play any sound, I tried grounding the powerguard circuit to disable it but that doesn't work it's still on, does anyone have any idea of what could cause this? Got the amp at a great price even if it's not working but still have 30 days to send it back if repairs are going to be more expensive than getting a working one. I opened the bottom of the amp and there are no signs of burnt components anywhere, I'm pretty handy with DIY but this would be my first time fixing an amp so I'm pretty lost. Any help will be greatly appreciated 
Best regards
Jake


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## bnae38 (Oct 3, 2015)

Study page 14 of the service manual.

Could take some time to get your head around it (i havent spent any time on it before, other than a minute ago)... 

I would start by measuring dc on each channel pg to see if any are different from the rest. They're labeled Pg1-pg4 (5 and 6 as well, though not sure where they come from at the moment lol).


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