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Goldilocks and the three Guyatone EQ pedals (with unresponsive bands)

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  • Goldilocks and the three Guyatone EQ pedals (with unresponsive bands)

    Once upon a time a Japanese company called Guyatone made a line of pedals with the same chrome and fonts used for toyz made in Japan back in the golden 80z. I got the EIGHT band PS-012* graphic EQ for $50, but:

    1. The sliders were a bit stiff. When I cleaned out the dust, I pulled out a little bit of metal out of the 500Hz slider along with it. Then that slider and the 250HZ slider next to it stops working....or so I thought.

    2. So I got another one for $50, and sprayed it with Dexoit Fader Lube. The 250HZ slider stops working... yet when I took it apart at tested the slider, and the part seemed to work!

    While I was in there, I had a look around and was surprised to see about EIGHT transistors (KA30, C1571) along with two of the usual quad TL064 opamps you'd expect to find in an EQ, plus a TL4558.

    3. Now obsessed because basically it sounds as cool as it looks, I order a THIRD one for $60 that's even cleaner than the first two in the original box. Most of the sliders are scratchy, but 500HZ and 4000 HZ do not work...

    *There is also PS-036 which is basically the same pedal in a different enclosure. I tried one in a local second-hand shop, and at least TWO of the bands did not respond.


    I know the jokes are already writing themselves and at my expense, but now I am of the opinion that the sliders in 1 and 2 were faulty before I got them, and that the problem lies somewhere on the PCB where but before I start invasive diagnosis and waste a lot of time probably only to put some charming vintage junk out of its misery, I'd like to get an experienced opinion about where the failure might be.

    My guess is that it's some of the transistors maybe used to "boot strap" or tune some of the EQ bands to overlap because it sounds so natural, but do TL064 have a high rate of failure? Where should I start?




  • #2
    Do the sliders mount directly (solder) to a circuit board? If so I would resolder all the slider connections.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #3
      Are these pedals used ? Sliders don't do well on the floor . Too much dirt ( and not the good kind ) . I would look at the sliders and if you ever get the clean , put it on top of the amp .

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      • #4
        It works now after I cannibalized another one, and replaced the sliders. Thanks everyone for the input.

        Now to think about modifications to reduce hiss. Any recommendations for upgrading the TL064?

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