Audioguru, I have replaced the power transistor (Q4), R7, Q1 and tested with a (just purchased) multimeter to see whether any of the capacitors are non operational but still no output from the power supply. I don't think any of these were blown but they seemed to be likely candidates, so replaced them. Not sure what to do next. Would the op amps be the problem? If so how can these be tested? Replacing them? Thanks, Philip