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Sparky67 · 18th Oct 2021, 4:28 pm

I am actually in the middle of doing this myself John on a couple of 320's, one faulty, and bought some axial caps for the job. They were selected to fit rather than their ESR and temp ratings - the PSU runs quite cool.

The 10uF 160V synth caps are working OK and C8 (2.2uF 160v) on the PSU 110V line is OK, but the cap I fitted at C6 (4.7uF 160V) I *think* may be causing the 110V supply to drop down to 60V-ish... Refitting the tant has brought the 110V rail back up. I now have a low ESR cap on order to try at C6. Slightly higher-uF value caps than the non-standard values originally fitted slow the lock time down a little, apparently.

A second PSU was found to have a couple of low gain transistors and I am looking at replacing a third device which appears to be faulty in use but not on the tester...!

I have also bought the LM2956 DC-DC converters and Nixie tube driver, plus associated filtering components, to rebuild the whole PSU as per the information on the PRC320 group on groups.io That looks a very viable long-term option as long as any remaining switching noise doesn't degrade performance. I will be taking S/N measurements at various freqs before and after fitting a rebuilt PSU to test that. Lock time is said to be almost instant.

Martin
G4NCE

18th Oct 2021, 4:28 pm	#2
Sparky67 Heptode Join Date: Feb 2008 Location: Great Barr, Sandwell, West Midlands, UK. Posts: 589	Re: Clansman PRC320 Replacement Capacitors I am actually in the middle of doing this myself John on a couple of 320's, one faulty, and bought some axial caps for the job. They were selected to fit rather than their ESR and temp ratings - the PSU runs quite cool. The 10uF 160V synth caps are working OK and C8 (2.2uF 160v) on the PSU 110V line is OK, but the cap I fitted at C6 (4.7uF 160V) I think may be causing the 110V supply to drop down to 60V-ish... Refitting the tant has brought the 110V rail back up. I now have a low ESR cap on order to try at C6. Slightly higher-uF value caps than the non-standard values originally fitted slow the lock time down a little, apparently. A second PSU was found to have a couple of low gain transistors and I am looking at replacing a third device which appears to be faulty in use but not on the tester...! I have also bought the LM2956 DC-DC converters and Nixie tube driver, plus associated filtering components, to rebuild the whole PSU as per the information on the PRC320 group on groups.io That looks a very viable long-term option as long as any remaining switching noise doesn't degrade performance. I will be taking S/N measurements at various freqs before and after fitting a rebuilt PSU to test that. Lock time is said to be almost instant. Martin G4NCE Last edited by Sparky67; 18th Oct 2021 at 4:40 pm.