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Thread: Hartke LH1000

  1. #1
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    Hartke LH1000

    Came in with Channel B PA blown. 7 of 8 BJTs (C5200/A1943) shorted.

    I removed them all. Added 4 1k 2w resistors from B to E. 2 on each side. Not sure if I need to do all 4 on each side. I think JM Fahey or Jazz P bass suggested this on a previous repair.

    The voltages at the driver bases aren't symmetrical. Seems skewed positive. Or actually the on driver base isn't pulled negative enough. All other voltages look good to me so I'm stuck.

    All .22 ballasts are good.

    Any suggestions?

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    Last edited by lowell; 10-11-2017 at 09:41 PM.

  2. #2
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    Here's a pic. Had a technical hiccup.
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  3. #3
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    Ok ok...haha. Sometimes just posting forces me to analyse further.

    The limited Q312 seemed a likely suspect. Sure enough it was shorted B/C. Put the closest pnp I have in stock in there. MPSA56. Fixed.

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  4. #4
    Supporting Member Jazz P Bass's Avatar
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    Check the fan operation while you have it on the bench.

    I had one come in that the fan came on way too late.

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  5. #5
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    All 3 fans come on right quick.

    Reassembled the amp, voltages look great, works great. Wouldn't be able to say that if not for the Ampage community, who has taught me I don't have to be just a "tube amp" guy. Thanks to everyone!

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