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Sunfire True Subwoofer MK IV repair

If anyone is still following this thread my issue was resolved by replacing the 6x IRF640 power transistors. The only issue I have now is that the total output seems low, but not by too much, maybe 6db. It seems like the amp has to be at or near max gain most of the time. It will still develop plenty of volume if input levels are high enough, but it seems like it could be an issue when paired with more sensitive speakers. I'm betting it needs the output transistors replaced. I'll update this thread if I correct it.
 
Just found this thread, hopefully someone can help me out. I have a Sunfire Mark IV that I am repairing and am wondering what the voltage on JP1 and JP2 should be with the amp powered on, idle and no load (sub not hooked up). Thank you!
 
I was able to figure this out on a Sunfire MK II that was in pristine, original and working condition.

All measurements are in VDC with ground referenced at WP9 and the amp idle:

Without sub hooked up:

..................JP1......JP2
Standby...10.10....-5.32
On.............7.32....-4.98

With sub hooked up:

..................JP1.......JP2
Standby...10.59.....-5.53
On.............7.20.....-5.16

Maybe this will help somebody...
 
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These voltages are fine. You can tune them to the exact same opposite voltage by adjusting the RP1 or RP2 potentiometer at the amp board if you want. But here it's not really neccessary.
 
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