Check the parts tied to pins 1 & 2 of the regulator.

Leonard

"MarkC" wrote in message
...
Thank you all for your help so far.
I'm getting 170V at the collector of the HOUT but still can't find out
what's causing this unregulated voltage. I replaced the STK reg U4101
and the caps C4107 & C4105 and diode CR4106 but no help. How often does
T4101 go bad?
Mark