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Re: capacitors and rectification question could use some help

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Trevor Wilson

(i)

In Reply to: capacitors and rectification question could use some help posted by John PA on November 05, 2000 at 19:36:05:

OK, assuming you have wired the cap correctly (is there +ve Volts on the +ve terminal and -ve Volts on the -ve terminal?), then the next possibility is the ripple rating of the cap. Look for a really high quality cap, with a high ripple rating.
A few more questions:
Is the cap near the bridge rectifier?
Bridges will typically run quite warm, when used in such applications. Heat will accelerate damage to caps, significantly.
Is the Voltage ON THE CAP the correct polarity?
What brand of cap are you using?
Is is a good quality component?

Trevor

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Re: capacitors and rectification question could use some help John PA 14:51:54 11/06/00 (1)
Trevor:
The cap is hooked up correctly. It is near the bridge but this is a 25 amp 200 volt bridge that shouldn't run too hot. also there is space between the cap and the bridge to allow for ventilation. The manufacture (of the amp) recommended putting the cap across the + and - point on the bridge rectifier. The cap is 35 volt but I do not think it is specifically a high ripple cap. Cary Audio stated that they use many different types of caps in this circuit and with a voltage of 25 volts or more they never have a problem (they do not use high ripple caps here. The cap is a good quality but I don't know the manufacture).
I could place a cap at each of the tubes to get them away from the bridge but anywhere under the amp is warm. There are a couple of other electrolytic caps that function fine and are under a much heavier load.
Thank you so far for you help.
John
- Re: capacitors and rectification question could use some help Trevor Wilson 18:36:28 11/06/00 (0)
  I'll just betcha the bridge IS running hot. Nevetheless, if the orientation of the cap is correct and it is not near a hot running object, then the problem will, most certainly, be that of poor ripple current ability. You may need to seek out a cap, with the appropriate ripple current ability.
  You mention other caps, which are under heavier load. Do you know that, for sure? A filament supply for an amp, or preamp, is quite a tough load, in terms of ripple.
  
  Trevor

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