Casio MG-510 rebuild with Roland GK Kit GT-3

Taking a break from the Zalt project…

I had bought this broken Casio MG510 Midi Guitar from the 80’s for not too much money. The hex-pickup was shot – the previous owner had tried … something and it is beyond repair. The rest of the electronics seems fine. The main board still works. I tested that by swapping it out with my own (other) MG-510 that is still original and in working order.


The broken original Casio MG-510 hex-pickup.

Previously I had the idea to convert my own MG-510 to a Roland Guitar Synth pickup and connection, but I decided that would devalue my guitar, so I waited for the right moment to buy a second hand fixer-upper.

So when I had my ‘experimentation-guitar’ I bought the Roland GK Kit GT-3, the built-in version of the Roland GT-3 hex pickup, electronics and 13-pin connector.

I decided I wanted to keep everything original, so I could always restore this guitar into its original intended state. That meant that I had to make a new pickguard plate. I bought a piece of three-ply plastic and copied the shape, the pickup cutouts – but not for the hex-pickup and the potentiometer holes. I wanted three individual switches for each pickup instead of a 5-way switch (also easier to make in the pickguard). So I worked on sawing and filing out the pickguard. I created a small hole in the pickguard for the wires of the Roland hex-pickup to go through (they come out of the back of the pickup) because the hex-pickup itself could lay flat on the pickguard – no routing was needed there.


I write this as if I worked on it continuously, but the truth is that I started it then didn’t work on this for some time (as in months) and just recently finished it. Oh well…

When the pickguard was finished, I started soldering together the analog guitar ‘electronics’ (passives). I have three, double pole, three position switches: on-off-on for each of the pickups. The idea is that when a switch is in the middle position the pickup is off. This allows selection of what pickups to use or not to use. The bridge pickup is a humbucker and its switch coil splits the pickup. The other two single coil pickups have a switch that puts their coils in- and out of phase. This allows you to created sounds that weren’t achievable before.

The volume and tone knobs are original. Did you know there is a small capacitor over the volume knob? I left it for now.

After testing the analog part of the guitar I removed all the electronics – the control knobs on the front and the jacks/connectors on the back from their face-plates and started to lay out the GT-3 kit components. Turns out that it all fits just as is.


Here is the original back plate with the GT-3 kit 13-pin connector in there. I also put in the light here because I don’t like it, too ugly to put on the front, but nice to see if it’s on. The jack is a reclaimed one I had laying around.


The GT-3 kit has most wires included and some even already attached. I ended up flipping the 13-pin connector up-side down because of the lock. Now you don’t have to put your finger or thumb in between the plug and the rim of the guitar to unlock the 13-pin plug. About the only design-flaw in the original MG-510.


The control face plate has the ‘digital volume’, the GK/Guitar mix switch and I replaced those big ugly push buttons with a momentary mini switch.


Here you do have to solder on some wires but its all very clear from the installation manual that comes with the GT-3 kit.


The Roland hex-pickup wire (with connector) just makes it to the PCB-cavity so I positioned the small GT-3 kit board right at the edge of the cavity with the pickup socket closest to the neck-end. I used double sided (foam) tape to stick it in there.

You can also see I have hooked up the analog audio output jack.


After that you simply plug in all the wires in their respective sockets and screw the covers in place. Done.

I was pleased that the GT-3 kit worked right of the bat. Great stuff.

Published in: on September 21, 2016 at 8:23 am  Comments (7)  
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7 CommentsLeave a comment

  1. I have a Casio MG 510 guitar
    I’m looking for capacitors on the circuit card some have fell off and I am having a hard time finding them. The capacitors are the tall ones can you HELP!!

    The capacitors are (50v), (33 10v), (10 16v), (22 16v), (4.7 25v)
    What can I replace them with?.

    • Hmmm, if you don’t know then you probably shouldn’t be messing with it. If you insist, search for ‘smd electrolytic capacitors’ on ebay for example. Proceed at your own risk.

      • Thank you

  2. marcjacobi

    I noticed that you have put a gk pickup on the casio mg 510 guitar.
    Do you have the circuit board for that mg 510 guitar. I would like to buy it, no matter what the condition it is in if you would like to sell it.
    Thank you BJ

    • I have sent you an email.

  3. That’s a great job. I am planning the same on my Casio MG500 which is only working on 5 strings. Rather than attempt any more “repairs” I am putting a gk3 in. Thanks for the detailed post. I wondered about using the Casio pickup as mine seems ok. The string detection circuit is where mine is failing. Tried the cap replacement but no different. Rather than destroy the rest of the electronics GK3 looks like good option. Will keep you posted

  4. Thanks. I think it depends on the levels each pickup emits, but you can sure try. You could also try selling the MG-510 pickup as spare parts for these guitars seem sparse. Good luck with the build.

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