[Ian Bell]

My high speed A77 is running too fast. The service manual description of the
capstan servo talks about a resonant circuit used as a discriminater but
the circuit shows an NE555 instead. It's an old A77 and the capstan servo
PCB looks like is has the resonant circuit - no sign of the 555. I have
gone back through capstan servo circuits at the Studer web site and the
only one with a resonant circuit is in the A80.

So I don't have a definitely correct circuit for the capstan servo - need
advice on how to diagnose & fix this problem.

Cheers

Ian