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Harman Kardon HK6650r Amplifier Restoration (WD40 Edition)

Discussion in 'Electronics & Electrics' started by aokman, Jun 3, 2020.

  1. aokman

    aokman Member

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    Melbourne
    So I have had a hell of a project come onto the bench and I thought I would share this one. I don't normally work on newer old amps and I have never worked on a Harman Kardon amplifier before.

    Anyway purchased from seller as not working, his description of the problem is his speakers popped and no sound. Fine whatever I thought, blown outputs most likely. Then the story is layed out, he replaced the fuses roughly 10 times and get this... tried spraying WD40 through the amp to try and get it working!

    Needless to say, there is WD40 everywhere in this amp and it has made a hell of a mess... Can it be fixed? Lets find out...

    [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
  2. bonox

    bonox Member

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    What an oily mess - gives new meaning to No Smoking around this device i guess. Good luck :)
     
  3. Technics

    Technics Member

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    Wait... What... You're saying the fuse wrapped in aluminium foil and liberal application of WD-40 didn't work? Can't believe they gave up before trying duct tape.
     
    aokman and CQGLHyperion like this.
  4. OP
    OP
    aokman

    aokman Member

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    Disassembly started today, carnage everywhere, decided to soak all the boards in isopropyl bath and see what was left over. Started looking at the amp board and found the right channel had 3/4 output transistors blown. I think I have tracked most of the damage to a shorted capacitor which is a first for me to see a shorted Japanese capacitor but never seen this TK Audio brand before... The other channel aint far behind showing 100ohm on the same capacitor which sits next to the driver heatsink.

    Many many blown fused resistors also so need to check all the other transistors and at least 1 blown driver transistor.

    [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
    Last edited: Jun 5, 2020
    HSV_Enigma likes this.
  5. Caffeine

    Caffeine Member

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    You're more ambitious than me!

    My friend asked if I could take a look at his amp after his (saltwater) fishtank leaked onto it :sick:

    I haven't even taken the case off yet but I can see epic corrosion through the vents
     
  6. Mjollnir

    Mjollnir Member

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    You need one of them ultrasonic cleaners, perfect for jobs like this.
     
  7. OP
    OP
    aokman

    aokman Member

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    It was on my list but would need a pretty big one to fit these boards also :(

    More cleaning up, stripped the chassis down, dissolved the corrosion as best I could, a bit of paint and also dismantled the volume pot assy to rebuild and align the dual gang pots to ensure even volume across both channels. Some parts also arrived from RS and of course my luck, one cap got crushed. Also found one of those bastard RIFA caps hiding in the power supply waiting to go out in the blaze of glory!

    [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
    [​IMG]
     
  8. dakiller

    dakiller (Oscillating & Impeding)

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    At least WD40 isn't going to do any damage, just get soaked up by all the dust and make a nice gunk layer over everything.
     

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