On Thu, 3 Mar 2016 08:01:41 -0800 (PST), "
wrote:

Here is the Schematic: http://komkris4000.webs.com/lk150%20schematic.gif

It is eating the 150uF @ 75V filter caps - I replaced the OEMs first with 75V, 105F caps, they lasted about 20 hours. Then 100V, they lasted about 30 hours. The manifestation is increased HUMMmm, and the caps start to swell.

I am contemplating using 180V caps, but before I do so, any suggestions from the assembled multitude?

NOTE: All other voltages are correct and clean. When these caps are new, the amp is hum-free. As they age, a pronounced *60* cycle hum begins that appears to be volume dependent - that is, the hum goes down as volume increases.

The hum also remains with shorted inputs, and whichever way it is plugged in. US, nominal 120V/60hz single-phase (actual is 117V at the wallplate).

Thanks in advance!

Peter Wieck
Melrose Park, PA

Later rev schematics that employ silicon rectifiers in the -65V bias
have a 6K8 2W bleeder across the first filter cap.

RL