OK. First of all, a note to my fellow electronics neophytes:
Make sure your multimeter's battery is not weak. It may give you false readings if it is.
I believe I have isolated the problem to a SC25 op amp.
The voltages are stable at:
3 : 18v
5 : 18v
6 : 0v
But the op amp and the heat sinks get hot when it is left on. Also the Cinemag transformer gets overly warm.
After checking over and over for shorts, cold joints etc, and doing a few little touch ups here and there I finally decided to try to move the SC25 from my other A12 to this one. It works like a charm, stays cool to the touch and passes audio just like it used to. I left it on for an hour. I didn't heat up.
I then put in a Hardy 990C (I didn't want to leave it in long as I believe the voltages for this opamp are supposed to be lower.) Slightly warm, but still fine.
Then I put the old (suspected to be broken) SC25 into the OTHER, previously working A12. It exhibited the same exact symptoms (noise and heat after warming up) at first, then the power supply went dark.
Removing the suspect SC25 everything is fine again. Placing that opamp into either A12 will cause the whole box not to power up. Using the other SC25 and the Hardy 990c works fine and swapping them between A12s works too.
So, I suppose my question is if the SC25 has any sort of warranty?
I plan to order a WH01KA wire harness anyway and I suppose I will need another SC25 to go with it.
