Tolerance on value of last power supply cap

williaty · 1537

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Offline williaty

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on: June 24, 2014, 07:44:55 PM
I feel like we've talked about this before but searching doesn't turn up anything in the archives. What's the tolerance on the value of the last power supply cap? The biggest film cap I was able to find is 200uF and the stock value is 220uF. Is a 10% decrease in capacitance worth buying a 20uF film cap to put in parallel to the 200uF cap I have there now?



Offline JamieMcC

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Reply #1 on: June 24, 2014, 08:22:48 PM
Have a read through this thread it might help.

http://bottlehead.com/smf/index.php/topic,6030.0.html

Fitting a choke circa $10 and a smaller cap in conjunction with a smaller the last film cap 80-100uf  in the psu is has been done a number of times iT results in substantially less ripple 150u ish compared to the stock which looks to be s circa 15000u.

Though I am still unsure of the technicals as to why it works the combination of lower ripple with the choke combined with the lower ESR of the film capacitor I found to have some benefit and I was pleased with the results.

Shoot for the moon if you miss you will still be amongst the stars!


Offline Paul Birkeland

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Reply #2 on: June 25, 2014, 06:43:47 AM
The tolerance isn't super critical.  I would try to stay as close to 200uF as you can, but feel free to experiment with smaller caps and let us know what you find. 


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline williaty

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Reply #3 on: June 25, 2014, 08:33:38 AM
Well, the Solen PB 200uF is already in there, I just wanted to know if I ought to add some more capacitance to it. Sounds like I'm good to just leave it alone.