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"I've made a terrible mistake" - Gob

Discussion in 'Marantz Audio' started by StoryMe, Oct 30, 2018.

  1. StoryMe

    StoryMe New Member

    Messages:
    9
    Hangs his head and sighs.... I messed up.

    I needed to clean the knobs on a Marantz 2270 that I'd picked up and was refurbing a bit before putting into use. New bulbs, new velum, new power switch, cleaned pots. I was learning a bit as I went and had watched a youtube video suggesting that I soak the knobs in some 409 cleaner to clean them up. So I dumped some in a glass jar and threw the knobs in. Then forgot about them. Then left town for 4 days.

    When I took the knobs out, to my absolute horror, each looked like they'd been burned with a lighter. The structure of the knobs are the same. Same texture. No physical damage. But the visual is catastrophic. They are each their own very special brand of ruined: matted patchy black and splotchy chalky white.

    I don't know what to do. And of course these knobs are like $30 a piece on ebay. So I've essentially done something like $150 in damage in one fell swoop. The word crestfallen comes to mind.

    I'm wondering three things:
    Is re-plating possible?
    Is paint an option?
    Any leads on a reasonably priced set of replacement knobs?

    If anyone has any experience with similar or suggestions, or even if you just want to give me a hard time, I'm all ears. I certainly deserve it. I'm at a loss.

    Lesson learned: Don't soak your knobs in 409 for too long
     

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  2. eizner23

    eizner23 Active Member

    Messages:
    480
    Location:
    Madison, WI
    409 they still make that stuff?! Must have been the ammonium that did that. Soap and water works well.
     
  3. 62caddy

    62caddy Trust but verify Subscriber

    Messages:
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    Probably what happened is the protective clearcoat has been dissolved from the aluminum.
     
  4. Sandstrom

    Sandstrom Seldom turns out the way it does in the song Subscriber

    Messages:
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    I would try a good paste type metal polish like Flitz, Simichrome etc. It looks like the ammonia just discolored the metal. I would think you could bring those back with careful hand polishing...
     
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  5. StoryMe

    StoryMe New Member

    Messages:
    9
    Just the type of advice I came here for. I'll give this a shot and report back. Thanks Sandstrom
     
    onepixel likes this.
  6. kaplang

    kaplang Works for me ! Subscriber

     

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  7. Beemerdoc

    Beemerdoc Grumpy Old Fart Subscriber

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    Well, I would really like to bust your chops, but I feel generous today. :rflmao:

    Instead, Welcome to AK! :beerchug:
     
  8. Sandstrom

    Sandstrom Seldom turns out the way it does in the song Subscriber

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    Nope...

     
  9. Fairlane

    Fairlane AK Subscriber Subscriber

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    Little GTO, wasn't that Ronnie and the Daytonas?
     
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  10. Fairlane

    Fairlane AK Subscriber Subscriber

    Messages:
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    Sorry but you said time to polish the knob(s) :rflmao:

    Seriously good luck with your restoration. Sometimes things seem worse than they until you get in there and try.
     
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  11. onepixel

    onepixel .

    Messages:
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    I've used Simichrome and it works. You might even try some DeoxIT. It removes oxidation.
     

     

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  12. wlhd1610

    wlhd1610 Penny and her new friend Sponsor Subscriber

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    Let me know how you make out with them.
    I can help.

    Bob
     
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  13. Pio1980

    Pio1980 AK Member Subscriber

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    Simichrome or other polish will probably alter the original satin finish to something shiny.
    Be warned.
     
  14. Oerets

    Oerets AK Subscriber Subscriber

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    Welcome to AK!

    If you have access to a dremel type hand tool. They have a small brass wire brush and cloth attachments that may clean them up.
    Doubt it hand applied car or plastic polish will cut thru that buildup.
     
  15. Pio1980

    Pio1980 AK Member Subscriber

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    The black stain may be chemically reversed by the right treatment, but I don't know what that is.
     
  16. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    Finishing steel wool.
     

     

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  17. Fairlane

    Fairlane AK Subscriber Subscriber

    Messages:
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    Used this on the aluminum case of an Ampex preamp and it worked well.

    20181030_142416.jpg
     
  18. Sandstrom

    Sandstrom Seldom turns out the way it does in the song Subscriber

    Messages:
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    Location:
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    Agree, they will likeky become shiny, you might restore the satin look with a 3M maroon pad after cleanup...
    absolutely correct sir :D
     
  19. Pio1980

    Pio1980 AK Member Subscriber

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    I won't have steel wool anywhere around my work area. Maybe Magic eraser, nonmagnetic and non-conducting.

    Maybe this?
     
    Last edited: Oct 30, 2018
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  20. kaplang

    kaplang Works for me ! Subscriber

    Nope! 409. The OP used 409 cleaned. Didn't use GTO. Don't you get it?
     

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