The amp goes into standby after about 5 seconds. All the output
transistors checked ok, so I put an oscilloscope on supplies and
checked +/- B (50 volts). The +50volts are fine, but the -50volts
supply goes to -50volts and then within a second goes back to zero.
It has dual parallel bridge rectifiers, so at this point I am assuming
the main power supply caps, even though they checked out at 6800uf.
It is not the transformer, since I am getting a full sine wave even as
the -50volt supply dwindles. Main caps????????

Can you physically disconnect the B+ and B- from the output stage? This
might help further isolate the problem.

That's Floyd R. Turbo, by the way.

On Oct 28, 8:57 am, "William Sommerwerck"
wrote:
Can you physically disconnect the B+ and B- from the output stage? This
might help further isolate the problem.

That's Floyd R. Turbo, by the way.

No, I don't think so. I am going to replace the power supply caps to
see if it helps.

wrote in message
ups.com...
On Oct 28, 8:57 am, "William Sommerwerck"
wrote:
Can you physically disconnect the B+ and B- from the output stage? This
might help further isolate the problem.

That's Floyd R. Turbo, by the way.

No, I don't think so. I am going to replace the power supply caps to
see if it helps.


I'm pretty sure it won't ...

Arfa

"Arfa Daily" wrote in message
...

wrote in message
ups.com...
On Oct 28, 8:57 am, "William Sommerwerck"
wrote:
Can you physically disconnect the B+ and B- from the output stage? This
might help further isolate the problem.

That's Floyd R. Turbo, by the way.

No, I don't think so. I am going to replace the power supply caps to
see if it helps.


I'm pretty sure it won't ...

Arfa


I've seen several with bad voltage regulator IC's.

7815, 7915, 7905, etc.

I'm betting on one of those...


Mark Z.