Dead OCM 55...

It is a very simple circuit.

If one channel is working, that becomes your reference voltages for testing against the dead channel. Problem areas should take minutes to find.


Only the switches and pots are soldered in a way that chassis flexing/vibration could cause grief...and their solder junctions and overall continuity can be inspected.

On a scale of 1 to 10 in complexity of trouble shooting (easiest to most complex), A preamp this simple is somewhere down at the 3 range.

There are apparently two versions? If it is the following design, the simplicity remains:

Last edited: