Just bought a 1997 Daewoo Puma 8S. Have run 2 jobs on it so far. Just booted it up Monday morning and have the error in the title. I've identified that the middle amp in the top of the cabinet is not lit up.

This happened on Friday, and I turned the machine off, disconnected and reconnected all the DSUB cables going between amps. Turned the machine back on, and it started working and ran all day. Today, this is not working.

I've ordered a couple replacement cables, but am concerned this is not the problem since I can't get it to work today. If it's an intermittent cable I'd think I'd be able to get it going. Am I barking up the wrong tree? What else can I check while I wait?

The left AMP says "b" on the back while the right amp is flashing between "F1" and "E7". Can't find anything telling me what these mean.