I don’t often get an opportunity to do much repair on the bench any more but always enjoy it when I do get a chance to troubleshoot equipment at a component level.  A friend of mine gave me a Crown K1 amplifier that was completely non-functional.  This amplifier was released in 1994 and was revolutionary for its time.  It is completely convection cooled.  Most amplifiers have at least one fan.   Output is up to 750 watts in stereo (2 ohms per channel) or 1500 watts in mono (4 ohms bridged).  It produces this output while drawing less than 10 amps at maximum output and continuing to work even in harsh conditions (high heat, etc).  This amplifier sold for almost $2,000 new and has a reputation for good performance.

One (non-functional) Crown K1 Power Amplifier

Hmmm…Is this a problem?  The connector wouldn’t even come apart.   The two parts of the connector had literally melted together, never to be separated again.

Ouch.  This board is beyond repair.  Clearly some very high currents went through this circuit in the form of a direct short.  This is actually not an unexpected fault in the case of catastrophic device failure…My guess is that there was a “cascade” effect where one device shorted and caused the catastrophic failure.  Unfortunately the amplifier never shut down.  This was one of those “odd” failure modes apparently not picked up by the amplifier’s protection circuitry immediately.

This is where the board was mounted…You can see the arcing that occurred behind it…

The rest of the amplifier looks fine but there was a considerable amount of black carbon residue on cables near the failure point.  This ribbon cable was in the line of fire…Only minor damage and can probably be repaired.

This is the other (undamaged) side of the same amplifier. Presumably I should be back in business if I replace the failed output section and the damaged main wiring harness.  A relatively small investment in a decent amplifier that didn’t cost me anything…