KPA500 error

[James Jordan]

Problem solved!
Hard to believe, but after years that the cover interlock worked properly,
and assuming it engaged with the top screwed down, it didn't. Guy, K2AV,
suggested checking it again so I took off the cover and actuated the
microswitch. HV came on as normal. Looking closely there are only a couple
millimeters between off and on. Over time either the top warped a mm or the
actuator arm weaked a mm or two or both, but it was just barely not
closing. This amp has had a hard life traveling to VP5 and being exposed to
salt air, so some mechanical issues are not surprising.
I put a couple layers of Scotch rubber tape on the underside to make the
top thicker and now the switch closes with the top screwed down. Frankly,
it's a pretty kluge design not to have a more positive action on the
interlock, but discovering it without a trip to Watsonville was a huge
relief.
Thanks again to those who responded offline.
73,
Jim K4QPL VP5M