On Thu, 25 Feb 2016 09:00:07 -0500, legg wrote:

Sounds more like you're getting closer to root cause.

I'm afraid not. It didn't happen yesterday when I first hooked the psu
back into the scope so this is a fresh fault - and probably my fault for
not testing the psu's output voltages properly before plugging it back
in.

Troubleshoot the (unidentified?) signal board.

May have to wait til the latter part of next week; I have to leave later
today for a 5-6 days due to family-in-law commitments.