[Elecraft] KPA500 / 270V ERR

[Andy Durbin]

"He tells me that a failed R16 on the power supply board should have no effect on the 60V supply, ....."

No, of course it won't.  It will only prevent 270 V being produced if 60 V is present.   The amplifier is heavy and will be expensive to ship.  Why not diagnose the problem and just fix what has failed?

You have already determined that mains voltage is reaching the low voltage supply since you have the display and control panel working.  There really isn't much that can kill 60 V if there is input to the main transformer T1.

Failure can probably be isolated to T1, the diode bridge,  the 60 V enable relay, and their interconnections (assuming the power supply rails really have failed and this isn't a sensing problem).   The problem could be as simple as a poor contact on the transformer tap.  The hardest part of the job is removing all the screws to gain access to make measurements.

Perhaps the best thing about building a kit is not the small cost saving but gaining the confidence to open it up if needed.

Andy, k3wyc