HCA 1200 ii bias and output relays - diyAudio
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Old 8th January 2013, 02:23 PM   #1
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Join Date: Jan 2013
Default HCA 1200 ii bias and output relays

I opened up the amp to try and troubleshoot the output relays which are staticy at low volume and that brought up some other questions. The left channel heat sink was a lot hotter than the right, so I investigated the bias. I ended up adjusting to 10 MV from 8 on the left channel and 9 on the right channel. That doesn't explain the temp difference. Anyone have any idea why that would be? The amp sounds good and balanced to my ear- except for the random static at low volumes till the relays make contact. I also noticed that the output relays are in a tricky spot to work with, and looking online they are discontinued- they are


Has anyone had any success cleaning them? I could use some old-timer trick

I know they can be redone by sending the amp out, but I am out of work and on a severe budget crunch! Not to mention I enjoy fiddling!

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