[HAM] Those Pesky Cathode Bypass Capacitors

[David Anderson]

Scott,

In your experience with rebuilding/repairing AO-28s, have you found  
that these bypass capacitors degrade faster or more often than the  
high voltage supply capacitors?

The reason I ask is that in this 1970 preamp, just replacing the  
bypass caps really made the organ sound great. There is very little  
power supply ripple on the high voltage capacitors, ~10 millivolts.  
As I've said myself before, it's good to replace all these as a  
matter of routine maintenance, but perhaps the lower voltage sections  
just don't last as long.

I'm thinking of doing my next preamp rebuild with all discrete  
capacitors mounted under the chassis. Sprague/Vishay, Panasonic,  
Nichicon, CDE, etc... all make electrolytics that measure better than  
current multi-cans, though the venerable Sprague Atoms have jumped in  
price of late.

David
On Jul 22, 2008, at 11:28 AM, Scott Hawthorn wrote:

> [Exits quickly to replace them (again). Have a big rental coming up.]