JVC TM-H1950CG – RGB mod

 

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So, my trusty 17″ JVC monitor died a few months ago, and I’ve been searching for a new one. Not wanting to get ripped off by the insane £400+ listings on ebay, I’ve been sadly crt-less for a while (despite having the OSSC, which is fantastic) Then last week I came across the above listing – £25, which seemed crazy. I bought it immediately knowing it to be a very, very good 800+TVL monitor despite the lack of RGB which I later modded in (and this post shows the process). I got ready for the 4 hour round journey to pick it up, when disaster struck and I came home to find a recall notice in the post for my car. Not wanting to end up in a burning mangled ball of flames, I had to call off the journey and request a refund from the seller. He suggested letting them try and find a decent courier quote for me…which he did – £14! I sent the money over, and it arrived the next day.

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What’s in the box?!?!

Quickly set it up to test it. As standard this monitor only has composite and s-video connections. I was actually quite impressed with the quality of the composite input, likely because of the fact it’s an 800tvl monitor. Even so, the image still suffered from blur, colour bleed and the general shoddy drawbacks that composite brings:

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It works!
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DKC2 – Composite
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Super Metroid – Composite
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Yoshi’s Island – Composite
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Yoshi’s Island – Composite
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SMW – Composite
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Kirby 3 – Composite
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me and my daughter putting it through its paces!

I was surprised to find that the unit was produced in June 2007, not even purchased for a few years after that – and that it had barely been used. Can’t believe I got it for £25! Anyhow…it was time to add RGB. I had two options – to buy the JVC RGB input card which would cost literally hundreds of pounds, or to build an RGB input myself. I used this guide by TypicalNerveCell. I had a stripboard and components ready, so I gave it a go.

Firstly, I built the circuit. The guide above goes into detail, but I made one error which resulted in an issue later on – I could only find three 0.1uf ceramic caps, so for the sync line I used a random film cap in my kit of the same value.

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The monitor had an SDI card installed. Never gonna use that, so I removed the card and used the plate to mount a SCART input. Simply drilled two holes to secure it, and later finished it with hot glue. I hooked up R,G,B, sync and ground to the socket, and to the board. After the photo was taken, I also grounded each pin.

Next was to solder the R,G,B, sync and ground connections to the main board. I routed the wires through to the expansion bay where my card will sit.

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Mainboard/Jungle
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Wired up. Probably didn’t need the tape.
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Wires routed through

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Finished backplate

 

Testing time!

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uh oh

So that’s not good. I can see it’s the output from my SNES – but it’s obviously not right. I contacted TypicalNerveCell via reddit to ask, and it turns out I missed a part of the guide – I needed to short a connection to make the monitor think there’s an expansion card installed. doh. Dismanted it and made the adjustment…

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what the

So uh what the hell. The colour is right, but the white is inverted! The sync seems off…

I then realised what was going on. The sync overlays a monochrome image that the monitor uses alongside the rest. That film capacitor I used was actually an inverter which would explain the drug trip seen above. I remembered that I did actually have some more ceramic caps lying around (actually, inside an SA-1 cart conversion I built) so I pinched one from there and tried again.

Success!!

sdrhdrhdrcofcofhdrhdrhdrhdrhdrhdrhdrhdrhdrhdr

It’s a fantastic, crisp image. By far better than any CRT I’ve ever owned before…and all for £25 and a few hours work!

Running out of space now though…

dav

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