Roland RE-501 Motor Does Not Run / High Voltages On the PSU

[smilan]

Hi,
I have a Roland RE-501 that I was trying to repair. After replacing the motor bearing, it was working quite well except for the compressor and expander.

I discovered that both VR8 and VR9 were faulty, so I replaced them with new trimmers. While adjusting VR8, something around the motor or the three regulators (Q100, Q103, Q106) started smoking, and shortly after, the motor stopped running.

After further inspection, I found that both tantalum capacitors (C112 and C113) were shorted, so I replaced them. However, the motor still does not run, and all voltages appear to be too high. Instead of +15.6V, I measured +24V, and on the negative rail, instead of -15.9V, I measured -21V (measured on the power legs of IC101).

I tested Q100, Q103, and Q106 with my Chinese T7 multi-tester, and they seem to be fine.

What could cause the voltages on the PSU to rise so much?
Is there a way to test the motor and verify whether it is still functional or if it has burned out?

 

[Khron]

Instead of +15.6V, I measured +24V, and on the negative rail, instead of -15.9V, I measured -21V (measured on the power legs of IC101).

IC100/101's a uPC4558.

https://www.renesas.com/en/document/dst/upc258-upc4558-datasheet?r=495766

Powered with 45V total, there's a good chance they're toast. If they're toast, the pass transistors will be fully conducting, and not reducing the voltage by almost anything.

No guarantees the other opamps powered by those +/-15V rails are still alive... Which would explain the motor not running, if IC100's toast as well (Q106 is not "forced on" with a collector-base / emitter-base resistor, as opposed to Q100/103)

Voltage at the base of Q101 (connected to base of Q100) is near zero (instead of 4.5V), i'm guessing?