Hi all, I need help with a Peavey 1500. I replaced all 8 outputs on chanel A plus some other parts that were down and some that were supect I have gone over every component on the board for dry joints and tested each one at a time, the amp no longer trips out, protect led goes out then power led comes on so it all looks good but ( and this is my problem ) all 4 2sa1943 outputs get very hot within a minute or so, the 2sc5200 stay cool, again I have checked every part associated with this part of the curcuit and everything seems to be ok. I dont have a variac (if only!) so I am using the 100w light bulb method it lights up and stays tha way so i know its drawing too much power but with that out of the system the amp comes on as it should then stars to heat up very fast but just the 2sa1943's. If anyone out there chould help with this I would forever be in your debt. Thanks........
The protection triac is fine, there is no vr 125,225 not sure where to check for dc offset and as the amp is getting hot so fast i dont allow it it to stay powered for long.
Also the heatsink is isolated and by output drivers you mean the 15032/15033 transistors, then yes they are fine and all are genuine replacements
Also the heatsink is isolated and by output drivers you mean the 15032/15033 transistors, then yes they are fine and all are genuine replacements
Semiconductors never half fail. They are either open circuit or short circuit. Never replace components because you think they are not as they should be.
Is the original fault the same as you have now? If it is you must fault find in a logical manner.
If the current drawn only affects one set of transistors, the load must be something man made. Check the work done.
Is the original fault the same as you have now? If it is you must fault find in a logical manner.
If the current drawn only affects one set of transistors, the load must be something man made. Check the work done.
Yes i understand about transistors being good or bad, and no the original fault was a pair of outpus blew so to be safe I repaced them all as I was reliably told to do so wheather this is just to generate extra sales i'm not sure, all other parts were fine apart from the coresponding 5w resistors, the 1w 22ome and a couple of 1N4148 diodes Oh and the triac and yes it probibly is man made. what i dont understand is why the thing doesnt blow again on full 240v ac. If I leave the 100w bulb in place it wont reach the 78v dc that it should and the mains at the trasformer only gets to 90v ac which i've never noticed before. I have fixed 100's of amps and mixers in the past and usualy when all the bad parts had been replaced they all work fine plus I have repaired at least 12 of these peavey's and quite a few more other peavey amps and most of them are still in use on a daily basis but this one has got me baffled beyond belief.
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