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GW4FRX · 15th Feb 2018, 10:29 pm

Stock faults on RA177x PSUs seem to be dry joints on the pass devices and also the large rectifier on the PCB. If the +12V regulator fails the other rails collapse, which can be confusing, so a good strategy is to make sure that one is working before addressing the others.

Changing the four reservoir capacitors, rewiring the PSU harness in PTFE cable and adding fan cooling to the rear heatsink always seems to be a good move with an RA177x if you're planning to keep it.

I didn't know that Telford Electronics ever serviced these but there are plenty of people around with a lot of experience in fixing them.

15th Feb 2018, 10:29 pm	#12
GW4FRX Pentode Join Date: Aug 2005 Location: Shrewsbury, Shropshire, UK. Posts: 149	Re: RA 1772 power supply heat Stock faults on RA177x PSUs seem to be dry joints on the pass devices and also the large rectifier on the PCB. If the +12V regulator fails the other rails collapse, which can be confusing, so a good strategy is to make sure that one is working before addressing the others. Changing the four reservoir capacitors, rewiring the PSU harness in PTFE cable and adding fan cooling to the rear heatsink always seems to be a good move with an RA177x if you're planning to keep it. I didn't know that Telford Electronics ever serviced these but there are plenty of people around with a lot of experience in fixing them.