Ampeg B-15n HELP!!!

[stompjunkie]

Ok. I got the cap in this morning... and I've just replaced the multi-section cap can.

It's motorboating just like before.

I've replaced the other electrolytics with sprague atoms, and the 30uf with a 33uf 630v Solen....

Any ideas? This should have taken care of it, seeing as this is where the problem should be..... argh.

Thanks guys.

[selloutrr]

at this point you have replaced all elec's and the decoupling cap? Motor boating is almost always a sign that the decoupling cap is not decoupling properly and going high impedance. If you have replaced all the caps i'd go back and check for cold solder points and make sure the polarity of all the caps is correct. Then Meter to ground and trace continuity to make sure your wiring isn't off or the wire dressing isn't creating a path for arching, voltage will always take the path of least resistance. If the amp has ever worked properly and you are just rebuilding it part for part the motor boating is isolated in the decoupling caps.