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KA-6004 Recap, repair and issues with the right channel

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by bhowle, Dec 3, 2018.

  1. bhowle

    bhowle AK Subscriber Subscriber

    Messages:
    9
    After pulling this thing out of storage and firing it up, I've found a few issues that I'd love some help with.

    #1: When first powering the amp on, the source indicator and pilot/power lamps flicker, along with an electrical crackling noise coming from the power transformer. After some time (30 seconds to 2 minutes), it will stabilize and the speaker relay will click on. I've used deoxit and a q-tip on the power switch contacts with no real improvement. At this point, I'm thinking it may be the large power supply caps failing. I have ordered some Nichicon golds to replace them. Any thoughts? Am I on the right track with cap replacement?

    #2 I get an intermittent pop from the right channel while listening, that does increase with volume. It is present on all inputs, regardless of anything being connected. DC offset is around 6mV on the left channel, but the right fluctuates wildly, around 35-45mV with spikes up to 70mV. Is this a transistor issue?
     

     

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  2. gort69

    gort69 AK Subscriber Subscriber

    Messages:
    1,118
    Location:
    Vancouver, WA
    Issue #1 is most likely a failing power switch. You can (safely!) "jumper" across the switch posts to confirm. No experience with that amp, but a new replacement is probably available from Mouser or Digikey. You'll need to measure the screw hole spacing - post a photo and someone can likely help you find something that will fit. Something like this
     
    slimecity and bhowle like this.
  3. bhowle

    bhowle AK Subscriber Subscriber

    Messages:
    9
    Thanks! I will get some pics and measurements with the bottom cover off. I got a lot of nasty residue off the contacts with deoxit the last time I had it apart. I'm thinking of using some fine emory cloth/sandpaper on them, just to see it it temporarily improves the issue, and I'll try one of my heavy jumper leads across the posts to see if that fixes it.
     

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