NM - Answer my own question here.. Tops of the ic's were scratched some, I put some alcohol on a couple of them(to get rid of the white scratches some) and was able to read 6N137 - fairchild optocouplers...
If that's true, the schematic diagram for the SLA1500 may be helpful if you can't get one from audiopipe.
I got the schematic from audiopipe, but it is rather limited and doesn't have the full circuit.. I've got good voltage & input signals on the opto's, no output though. SLA1500 schematic?
email sent, also cc'd you the audiopipe doc they sent me.. This has been one strange repair so far: One channel (one half) had a shorted rectifier. The other half has no drive signal on the outputs (also had a shorted pre-driver, mmbt41/43 pairs)
Not yet, they didn't test bad in the board at least. I'm just looking for what is smashing the gate drive signals coming from the driverboard. And thank god I have square waves coming from the driverboard as it is almost entirely epoxy coated!
With NO outputs in the circuit (<< VERY important), connect the side of the output filter inductor that's connected to the output transistors to the amp ground with a jumper. Make sure that there are no solder bridges between any of the output transistor pads. Does that allow you to see the high-side signal?
The high-side is floating. When you tried to view the signal, there was no reference so it appears that there was no signal. It's essentially the same as trying to measure voltage when using only one multimeter probe.
makes sense, voltage on the outputs only happens after a second or two of the amp being powered up, rail voltage is already +-65 volts *before* the output goes high. Now to find what blew....
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