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 tries … 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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Published in: on September 21, 2016 at 8:23 am  Leave a Comment  
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