Master Control Panel 5500 volume wheel diagnose:
Make sure good batteries are in.
Rotate the volume wheel.
- If the MCP lights up but volume is not changed, the wheel switches are fine and the opto dead.
It's a three-pin device reading the black/white pattern printed onto
the side of the (inner part) of the volume wheel. The opto and its light output is known to degrade.
I have a few original, factory new optos in the drawer.
- If the MCP does not light up, as in no reaction at all, the switches are bad and will need cleaning or replacing (or something else is wrong).
Martin