Sony AV-3650 service manual

[RJMiranda]

I have got an AV-3650 in very good state and want to use it to digitize some videotapes from the early 80s. The machine is even clean on the inside. I lubricated it and tested the mechanism. Everything OK.

The heads are in good order, and surprisingly, the belts and capstan are in perfect condition. They don´t make rubber parts like that any more. I have a good enough RF level coming into the demodulator. The input signal is passed all right to the output in EE mode.

But in play and record the capstan is turning too fast. This model has a separate DC motor for the capstan, as it was an "editing deck" of the era. The tape runs at about twice the normal speed. I measured the voltage at the capstan motor, at about 13 V. I remember many years ago, when I used to repair other Sony VTRs, it was supposed to be from 5 to 7 V.

The power transistor is not shorted, and its base voltage is about 0,7 V higher than the emitter voltage where the motor is connected, so the trouble comes from somewhere in the servo circuit.

The trouble is, I do not have the service manual. I could try to trace back the circuit visually, but not knowing the correct voltages nor waveforms, it will be very difficult to find the cause of the problem.

There are one or two places on the Web where the AV-3650 service manual can be downloaded for a very reasonable fee, but you know, I live in Cuba, and not having an account in a US bank, must limit myself to free downloads.

Maybe somebody can tell me where can the service manual be downloaded from?

Thank you very much.