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Thread: peavey studio pro 112 smoking then bang :( help

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    peavey studio pro 112 smoking then bang :( help

    ok i got this amp off ebay about 2 years ago it was fine for a year of that then about 4 months ago its went click click click somke bang.

    i have found the chip that went and have a picture of it for you how bad is it is it worth replaceing??



    cheers james

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    come on guys anyone?

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    That Chip is either a LM3886 or a LM3875 Power amp IC.....

    They cost about maybe $10 each but they shouldn"t just Burn up like that unless there is some other Problem Like a Short or some other Problem....

    I would suggest removeing the Chip and Inspecting all of the Traces on the PCB to make sure there aren"t any Shorts and make sure there is no Contact with the Heatsink and either 0v (Ground) or +V because that particular Chip isn"t thermally or electricly Isolated from the Heatsink so without any Isolation the negitive Voltage conducts through the heatsink and will short out if it touches Ground or Positive Voltage.....

    You might try replaceing it with the Isolated version of the Chip to eliminate the potential of this happening or useing a Thermal Isolation pad between the Chip and Heatsink......

    If it is just the chip that is fried and there are no other problems then I would simply replace it.......

    I recently built a 50w Guitar Amp useing one of these Chips and I am bulding a 100w Bass amp useing 2 of these Chips right now and they make good amps for everything from Guitar,Bass, PA"s, Active Monitors, Power amps Stereo"s ect and can be implemented with as few as a dozzen external Parts (resistors and Caps) ........


    Cheers

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    yep its the LM3886T, well im gonna take it to a amp tech some time just wanted an idea of much it was gonna cost me to get fix cheers for the help

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    Lifetime Member Enzo's Avatar
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    Your insulators look fine from here, but the isolated package idea is good nonetheless. It is likely nothing more than the chip failure. I doubt it is involved, but bend C109 away from R128 so they don't touch.

    Your tech will surely notice, but tell him the power amp IC has blown apart so he knows you know. It should cost you the bench charge plus parts. In my shop you would probably pay $50-55. Make sure the speaker is OK and teh speaker wiring in good form.

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    I doubt it is involved, but bend C109 away from R128 so they don't touch.
    yeah i did that after the photo was took

    Your tech will surely notice, but tell him the power amp IC has blown apart so he knows you know. It should cost you the bench charge plus parts. In my shop you would probably pay $50-55. Make sure the speaker is OK and teh speaker wiring in good form.
    will do thanks for the help!

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