Help fixing Revox B77 reel to reel.

[Sushant Sharma]

Hello all,
I have enjoyed my B77 for a year or more. Playback was spot on but recording was not.
Lately the machine has developed problems with the power supply and refuses to turn on. I can't get requisite regulated and unregulated voltages at check points. I have only partly recapped the boards.

Does anybody have experience with this machine and can help with some trouble shooting. Will really appreciate that.

Thanks

 

[anilva]

Sent you a WhatsApp message.

 

[Sushant Sharma]

Update:
Checked and rechecked the regulated and unregulated voltages. That's where the fault lay. Thankfully the power supply board has a few components and I had replaced them all already.

Found the problem at one of the fuse holders on the ps board. The fuses I had checked (after taking them out of the fuse holders) and they were all good. When I touched the multimeter prong to the fuse holder (with the fuse inside it) the capstan started rotating and vu meters lit up. Phew....
Set the capstan motor to 800hz. Tachometer reads fine.

Thereafter, I cleaned up the audio electronics board and that brought back one of the channels that was misbehaving. Cleaned the switches etc on this board.

The tape calibration is still as was when I bought the machine. I have all the piher trimmers but have only changed the capstan trimmer as this can be done with just a multimeter. The others need test calibration tapes and equipment so they will have to wait. The old trimmers all work so I am not in a hurry.
Thanks for reading.