As a follow up to my earlier post. PREVIOUS POST
Jim G3KAF contacted me as have (several others over the years) about a problem he had with this well loved PSU. Jim had a voltage regulation problem. The Voltage dropped when current increased.
Jim like me would have liked a circuit diagram for the PSU, he managed to identify the value of a capacitor from my photograph. The fault remained though, only a few days later he found the problem.
On the small board with all the components the diode which rectifies the low voltage ac supply (next to the 470uF 12v capacitor) was highly suspect because the 470uF was getting warm!. When I took the diode out and checked it, I found it was a dead short circuit. Having replaced it the PSU is now working superbly well. I had changed all the 8 smoothing capacitors and the bridge rectifier and now I can go from zero amps to 20 amps and the voltage only drops 10mV (0.01 of a volt). I suspect it has not performed this well for years.
Thanks Jim for the information, if anyone has a circuit diagram or other information / faults found, please contact me.