On Jun 5, 12:16*pm, Kenneth Scharf wrote:
On 06/04/2011 10:07 PM, raypsi wrote:

hey OM

The dead give away should have been *the series resistor to that OA3
heating up big time since P=I^2R the current doubled, the power
quadrupled that resistor would have could have let its' smoke *out.

73 OT
de n8zu

Unless the original designer was paranoid enough to use an over sized
resistor in the first place. *Back when I first started out in ham radio
building with tubes I was guilty of using a 50W resistor in a 5-10 watt
circuit. *(half because I got the 50W part cheap and half because I knew
that I didn't quite know what I was doing and wanted to be safe).

In my case problem was only momentary, maybe a second sometimes going
days without doing it sometimes 3 or 4 times in a couple of minutes.
For a long time I was convinced it was in the amp instead of the power
supply because I once disconnected the power supply from the amp and
it ran continuously for a few weeks without failing. This turned out
to be just bad luck. Fortunately I am on the air about as sporadically
as the amp was failing. There is no telling how many times it failed
while I was using it and I just didn't notice.


Jimmie