Hi Folks
Hving succesfuly fixed an Ashdown with some great advice from Enzo Roly and JM Fahey. I've now moved on to another repair, a Warwick xtreme 10.1. It had blown lots of stuff including most of the output transistors, the drivers and all the transistors to from the diff amp onwards (bias stuff etc). I replaced it all and it seems ok now except I have about 65mV of DC at the output. Is that too high or is it an acceptable amount? if not how do I adjust it out?

And yes I know the attached schem is from the tube path 10 but the power board in this amp is the same, with a few additions from the xtreme 10
Cheers
Shane

Hi Folks

I've been trying to fix an Ashdown MAG250 which a friend of mine owns. It had blown a fuse and was not producing any sound.
I replaced the output transistors and checked all the others on the power board but still it was showing an apparent short (light bulb limiter stayed lit up and the amp produced a loud hum).So checking more deeply I found that the positive supply was being pulled way down and the negative was pretty much OK.
So I did some more measurin' and figured I may have a shorted smoothing cap(one did measure low resistance) and changed the main caps.
Now plug her in (still with light bulb limiter) and hey she's OK...BUT... turn it on with the speaker connected and we're back to the positive side pullin loads of current...ahhh.
Weirdly if I turn it on without the speaker connected then plug the speaker in its fine! even if I then turn it off and on still with the speaker connected it's OK but if I leave it a while and turn it on with speaker it swings again and I have to disconnect the speaker and plug it back in to get it to run OK.

Ok so I'm stumped...(not difficult!).. Anyone got any Ideas? I know amps can tilt at turn on but dont normally stay that way!

Cheers
Shane