Looks like the schematic for this power amp is hard to come by. Maybe some of you that have access to it can help me out. The preamp is good. I am able to get clear sound out of the line out. The power amp output gives me a DC voltage starting at -9v and slowly drops to -2v and resembles something of a square wave on the scope. When I try to run a signal through it I can see an "attempt" to reproduce the negative half for a split second and it goes away. Turning post gain down and back up, it will do again then die. I have tested all the transistors with my DMM and I haven't found any issues yet. One thing I thought was odd was the optocoupler chip. I was not able to get a diode drop on pins 1 and 2. Pins 4-6 check just like a transistor.
Heading to check voltages now and will report back. Any ideas?
One thing to note is a previous repair company in town swapped the fan out for a 120V AC fan. Of course they wired it wrong and it is now dead. As a result, I have checked the power transformer and it is good. Not sure if the DC fan being deleted from circuit will cause any issues. Schematic would help there..
Heading to check voltages now and will report back. Any ideas?
One thing to note is a previous repair company in town swapped the fan out for a 120V AC fan. Of course they wired it wrong and it is now dead. As a result, I have checked the power transformer and it is good. Not sure if the DC fan being deleted from circuit will cause any issues. Schematic would help there..
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