How to fix scratches on pre-amp display?

Discussion in 'Audio Hardware' started by Johan Bos, Mar 14, 2019.

  1. Johan Bos

    Johan Bos Active Member Thread Starter

    Location:
    Netherlands
    Hi, recently I bought a second hand Quad 66 pre-amplifier. It looks very nice except a few scratches on the display. I'm wondering if I can replace / repair it. Do you have any idea? For instance, can I polish it?

    This is a picture of the display:

    [​IMG]
     
  2. Tonmeister

    Tonmeister Forum Resident

    Location:
    New York
    There’s the Novus Polish kit available in the U.S. from KAB that is for removing scratches from dust covers, but would also work for your display panel. I have found that any scratches that can be felt with a fingernail should get a light sanding with very fine sandpaper first, before using the first polish.

    [​IMG]

    KAB Electro Acoustics http://www.kabusa.com
     
  3. rodentdog

    rodentdog Forum Resident

    Try toothpaste first. You already have it. I use it on scratched cds and it works pretty well.
     
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  4. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Problem with toothpaste is that it usually does not have enough grit to polish something that has large, obvious scratches like your photo shows.

    Jeweler's rouge or other professional products are likely needed, like the products that have been previously recommended to you.
     
    Fishoutofwater likes this.
  5. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    If you are really in to making the scratch be gone, then you'll want to remove the panel to work on it.

    Then: Micro-Mesh® Acrylic Plastic Hand Kits and several hours to wet-sand, from the grits that grind the surface flat to below the scratch, to ultra-fine grits that rectify it like glass again.
     
  6. Carrman

    Carrman Forum Resident

    Location:
    Toronto
    I always thought the trick with toothpaste and similar methods is that it basically fills in the scratches rather than buffing them out but I could be wrong.

    A google search for fixing scratched plastic will give you a few different methods to try.
     
  7. slovell

    slovell Retired Mudshark

    Location:
    Chesnee, SC, USA
    Plastic headlight restorer polish?
     
  8. Alan Beasley

    Alan Beasley Forum Resident

    Location:
    Ohio
    Try Flitz Polish. You should be able to find it at a hardware store.
     
  9. The FRiNgE

    The FRiNgE Forum Resident

    I use Meguiar's Ultimate compound for many different materials, gloss paint, plastic, and to remove patina from metal (including electrical contacts) It is the black bottle and must say "ultimate compound" which is micro-polish. The bottle that says "polishing compound" isn't the same formula. It contains no wax.

    A better product is 3M "Finesse It II" #o5928 ... expensive but really good stuff.

    Be sure to mask (with professional grade masking tape) any matte painted surfaces as the micro polish will "shine up" matte paint. (and it will look awful) If the plastic has any deeper "feeler scratches" wet sand in one direction with #2000 paper, then polish. The cloth may be soft cotton or microfiber.. either will produce excellent results. (In my youth I was a professional auto-body person and have restored several classic cars)
     
  10. WiredChuck

    WiredChuck Forum Resident

    Location:
    Bay Area
    +1

    I've used this technique to polish scratched plastic headlights. Should work on your pre-amp.
     
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  11. Roger Beltmann

    Roger Beltmann Well-Known Member

    Location:
    helenville, wi.
    I agree with Alan. Flitz works the best. I've been using it for many years. Get the stuff in the tube and not the liquid. Works great on dust covers, stickers, CD's and all types of metal , It's also a great nitro solvent for cleaning your firearms.
     
  12. Wasabi

    Wasabi Well-Known Member

    Location:
    Lutz, FL
    Another vote for Flitz. Good chit. :cool:
     
  13. Claus

    Claus Restaurant Critic

    Location:
    Germany
    Nope...... you can't fix those deep scratches !!!
     
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  14. hbucker

    hbucker Member

    Location:
    Denver
    I would use clear-coat polish for cars that is designed for removing scratches. I've had amazing results on turntable covers by using this as directed.

    I agree though, there probably is no fix for the deep scratches in the photos. The rest of the display can be polished to look new though.
     
    bradleyc likes this.
  15. SandAndGlass

    SandAndGlass Twilight Forum Resident

    The best hope for the deep scratches is a buffing wheel with Jeweler's Rouge of buffing/polishing compound.
     
    TheVinylAddict and Wasabi like this.
  16. Roger Beltmann

    Roger Beltmann Well-Known Member

    Location:
    helenville, wi.
    I agree with Herr Klaus. Nothing will remove deep scratches. But somehow Flitz makes them much less noticeable. Molecular flow? By the way, Flitz is manufactured in Deutschland in bulk. Then shipped to US and packaged. It also works magic on yellowed headlight lenses. Barnesite is much faster than jewelers rouge. I've used it when polishing out telescope mirrors. Cerium oxide is even faster but can give a orange peel type polish. Not suitable for optics.
     
    Last edited: Mar 15, 2019
    SandAndGlass likes this.
  17. Socalguy

    Socalguy Forum Resident

    Location:
    CA
    Wet sand with 2000g, then 3000g, then buff with Meguiar’s 105 compound.
     
  18. FIrst off - those scratches look a little deep. All the household remedies like toothpaste and even commercially available solutions for things like headlights / plexi and you're going to be rubbing for a while! Most of these are made for light swirling and very light scratches --- but if the scratches have any depth it can be a chore. Then compounded by the fact you are working on a piece of plastic installed on a component and trying to work with compounds or pastes / chemicals........

    I say remove it from the component if possible, take it in your shop and install two 8" cotton muslin buffs on your Baldor 332B buffer (1800 rpm of course the 3500 rpm too high) -- one 8" concentric 1/2" sewn wheel for the heavy scratch removal and one loose sewn wheel for the final polish. Use a jewelers rough (like a pink / red) or a myriad of other compounds / pastes made for plastic. :) It'll make that puppy glisten!

    This is what I use for TT dustcovers too --- I can make a scratched up vintage top an 8/10 in minutes --- then finish it by hand for the remainder. I should do some before and after some day.

    BTW --- I am kidding I know you probably don't have a Baldor buffer! BUT if you are going to do it by hand try and get it out of the component so you can isolate and apply elbow grease

    Photo of my Baldor in my woodshop....... freakin handy tool for so many things
    [​IMG]
     
    Last edited: Mar 15, 2019
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  19. bradleyc

    bradleyc Forum Resident

    Location:
    Midwest
    Might try some of my Meguiar’s Ultimate compound on a CD or two :)
     
  20. I just saw this --- yup. I kind of elaborated on this a bit in my post above!

    Either way with the depth of the scratch, if cleaning by hand or wheel --- hopefully it can be removed from the unit because hand cleaning it will require some rubbing and it will be tough if it is in the unit.
     
  21. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Needs some kind of buffing wheel and real compound. Toothpaste and had rubbing is not going to work.
     

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