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AVT150H, fuse and resistors.

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  • AVT150H, fuse and resistors.

    Greetings After a 30+ year layoff I'm back at the bench as a hobby. Many thanks for the resources here.
    I've got a Marshall AVT150H with a blown fuse. It has a couple of burnt resistors near the three prong connectors, R110 and R112, I've read all the archived post referring to this problem and never saw these resistors mentioned. I'll need a schematic for this guy. Thanks in advance.

  • #2
    Those are 10 ohm 2w resistors in your Zobel networks or stability networks across the output of each module.

    They burn up when the amp goes into high freq oscillation.

    Replace them. If one power module is blown replace both. Mouser usually has th best prices on the TDA7293 IC.

    I can't believe we never posted the AVT150 schematics, but here they are.
    Attached Files
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Thanks Enzo, I've read many of your post's.
      There were no mention of those resistors in the blown fuse archives, and I couldn't access the schematics because I had never registered here. If I order the resistors and modules, would I have all I need, providing there are no other issues? or would I need some sink grease for example. I'm equipped for tube amps. Thanks

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      • #4
        Yes, you should have some heat grease. Does Radio Shack still sell little tubes of it?

        Those resistors don;t always burn up, I just can tell you why they do when they do. SYmptoms rarely confine themselves to a list.

        OF course I can;t tell you what else may have been damaged in your particular amp.
        Education is what you're left with after you have forgotten what you have learned.

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