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Posted: Sat Nov 17, 2007 5:28 pm
by Austin_OLaughlin
hey i was in the middle of a set and my orange ad 140 just failed me mid song. I was wondering what the problem is, i checked out the amp when i got home through different speaker cables and cabs when i got home and it sounds microphonic and i have to turn up the volume all the way to get sounds that cut off and on that don't sound like it is pure tone. i just wanted to know if it is the pre amp tubes, or the power tubes or both?

Posted: Sat Nov 17, 2007 5:50 pm
by screamingdaisy
Turn the amp on and tap one preamp tube at a time with something (I gently flick them with my fingernail myself). If it starts to sputter, sound broken, or give microphic squeals when you tap it then it's likely toast.

If none of your preamp tubes seems to be the problem the switch to checking the power tubes. For them, pull out the outside pair, turn on your amp and try playing through it. Then turn the amp off, pull the inner pair and re-install the first pair in the inner sockets and try playing through it again. If one of the pair are dead or making mechanical noises swap around the one of the tubes from the good pair to see which power tube is the dead one.

Posted: Mon Nov 19, 2007 11:08 am
by Andy H.
Potential reasons for Low Power or Loss of Volume:

http://www.geofex.com/ampdbug/lowpower.htm

Basically if it isn't a valve failure (though it likely is) you'd need to seek help from your friendly amp tech. In fact if it is a power valve failure you'd need to anyway to get the amp rebiased for new power valves. Heres hoping it is a nice simple preamp valve failure.

Let us know how its going though.


Andy.