Revox B126 CD Player Power Supply Troubleshooting Help Required

[dtm1962]

I have been repairing my B126 CD Player recently which has a problem on the Servo board, and I decided to take another stab at the repair.

I turned the unit on to make some measurements on the Servo board, I noticed the PS voltages were all wrong from the day before, so I decided to check the power supply itself and noticed the +5V & +10V & -5 & -10V supplies are now reading +0.2V (+5v) & +0.7V (+10V) ; -1.5V (-5V) & -1.5V (-10V).

Note this cd player has a standby power function as well which may complicate the troubleshooting

Refer to attached marked-up PS schematic pdf file for details.

Any help would be appreciated.

Thanks in advance,

[mjf]

hello.
can you test q2 /bc547.........(and perhaps q3 /bc557)...........perhaps they are damaged.
greetings

[dtm1962]

Since all the voltages on the base of the NPN & PNP transistors seem to be reversed, I am going to change out Q1 thru Q5 to be safe. I have checked the resistors as they seem to be OK but I will check again to be safe.

Thanks,

[dtm1962]

I found that Q1 & Q5 opened as a result of the TCA0372 Power OPAMP in the Servo circuit shorted out.

I replaced TCA0372 & the 2 transistors and I am back to where I started with CDM4/27 that does not read the disk at all.

I will add details in other thread....