On Sun, Jun 25, 2023 at 5:33 PM Rob Jarratt <robert.jarratt(a)ntlworld.com> wrote:
Thanks Tony. I removed the mains bridge rectifier and found it measured short across two
of its terminals, so I am ordering a replacement. I tested the PSU, without the mains
bridge rectifier and without the diodes on the output of the startup transformer. I got
24VAC on the output of the , the lamp limiter bulbs did not light and the fan in the power
switch unit turned. So it looks like the startup transformer is actually OK.
It's possible that the rectifier just failed. Or it might have been
damaged because it had to pass too much current due to a problem in
the main chopper circuit. I would certainly check the chopper
transistor for shorts now.
-tony