On the Disk ][ Analogue Board (691-92001), there are two trimmers, factory set and sealed with orange/yellow wax. On one of the drives that I have, one of these has been broken free.
The service books do not and never have mentioned adjusting these. Does anyone recall what each trimmer does, and how to calibrate them?
One of them is peak hold/detection timing. There is a bit on this one in Apple II restoration pages and a reference to Jim Sather's book, "Understanding the Apple II".
http://www.willegal.net/appleii/appleii-diskii.htm
The other may be disk rotational speed adjust, but it's on a different board, so I'm not sure if that is the one that you are refering to.
With the right tools, both are fairly easy to tweak.
regards,
Mike Willegal
Greetings,
The 2 potentiometers are described in the Disk II trechnical procedures pages 46 & 47.
________________
Antony
Apple II forever