Marshall AVT150H No power *Help*

redendever · 10-30-2009, 02:22 PM

I bought this DOA, I opened it up to see what the possible cause was. When I opened the amp I found a small plastic bag with 2 chips the same exact size, i notice that somehow they may mount to the bracet that the fans are mounted on. I remember one being ch1 and ch2, im guessing possible channels? Anyways, the wiring harness that conects to them, theres a blue one that would connect to each chip. One of the blue wire sets, had one small wire where i could see that it had burnt. Other then that theres no other traces of any problems wrong with the amp. I was told when I bought it, it would not power on. I guess they tried to put a new fuse in it which it then blown too. I was told they took it to a place to see what it would be to get repaired and was told 120$ to repair it. The tube looks good, there is still no fuse, but I have also heard if you continue to put fuses in it and they continue to blow you will cause an even more problem. Everything else seems to look in good condition. Also the transformer, i noticed that where the wires connect, it seems to be like the plastic clips that connect to the transformer may have recieved some kind of burnage. They are not deformed or anything, but I can see some black, and light black into the plastic where it connects. I'm not sure if they are made that way or not I do not smell any burn. If anyone has any advice at all that would be great. I would like to get this peice fixed. That is all that I seen when I opened it up, but Until I get a fuse, and find out exactly what those chips are for, how to mount them back to that bracket ( theres no screw wholes in the chips ) then I'm kinda out of options. You can post on here or feel free to email me as well redendever@neo.rr.com . I also have the schematic for this amp already. Thank you and take care!

Wilder Amplification · 11-01-2009, 12:56 PM

It sounds to me like one or both of the DMOS power amp chips shorted. Those DMOS chips pass a lot of current which means that when they short they have a tendancy to take a few other external components with them when they short. If you're not familiar with electronics I would suggest taking it to a tech. $120 seems like a pretty fair price to me for this repair depending on what other components were taken out due to the short.

10-30-2009, 02:22 PM	#1 (permalink)
redendever Junior Member Join Date: Oct 2009 Posts: 4	Marshall AVT150H No power Help I bought this DOA, I opened it up to see what the possible cause was. When I opened the amp I found a small plastic bag with 2 chips the same exact size, i notice that somehow they may mount to the bracet that the fans are mounted on. I remember one being ch1 and ch2, im guessing possible channels? Anyways, the wiring harness that conects to them, theres a blue one that would connect to each chip. One of the blue wire sets, had one small wire where i could see that it had burnt. Other then that theres no other traces of any problems wrong with the amp. I was told when I bought it, it would not power on. I guess they tried to put a new fuse in it which it then blown too. I was told they took it to a place to see what it would be to get repaired and was told 120$ to repair it. The tube looks good, there is still no fuse, but I have also heard if you continue to put fuses in it and they continue to blow you will cause an even more problem. Everything else seems to look in good condition. Also the transformer, i noticed that where the wires connect, it seems to be like the plastic clips that connect to the transformer may have recieved some kind of burnage. They are not deformed or anything, but I can see some black, and light black into the plastic where it connects. I'm not sure if they are made that way or not I do not smell any burn. If anyone has any advice at all that would be great. I would like to get this peice fixed. That is all that I seen when I opened it up, but Until I get a fuse, and find out exactly what those chips are for, how to mount them back to that bracket ( theres no screw wholes in the chips ) then I'm kinda out of options. You can post on here or feel free to email me as well redendever@neo.rr.com . I also have the schematic for this amp already. Thank you and take care!

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