Of the four 4-pin optocouplers, two adjacent one have pin 3 directly connected. Pull those. Does that allow pin 5 to charge (220k back in the circuit)?
Pulled those it’s not in protect and exactly like you said pin 5 is charging. It got around 8 and was still going so I cut it off to be safe
Both have pin 2 connected to the collector of a C3198 transistor. Check those transistors.
Are these U4 and U6?
Are these U4 and U6?
That seems backwards because one is near the 150k resistor that's used in the regulator circuit but if they're connected to the two 3198s, I guess they're the ones.
Reinstall the optocouplers but pull the transistors.
Does it power up or does it go into protect?
Reinstall the optocouplers but pull the transistors.
Does it power up or does it go into protect?
That seems right.
At this point, what's important (I hope) is that we're narrowing down the problem.
The other optocouplers should connect to a 431 regulator and to the switching transistor for the output stage (not sure which it would be without the driver board).
At this point, what's important (I hope) is that we're narrowing down the problem.
The other optocouplers should connect to a 431 regulator and to the switching transistor for the output stage (not sure which it would be without the driver board).
It's not critical but it's U17 near the edge of the board near U302 and U303 (clamped to the heatsink).