Video Output from the Game Gear

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I cannot claim to have invented the method of displaying the Game Gear's image on a TV screen. Credit for that must go to Victor Kemp (and others) who did the analysis and drew up a schematic for a simple decoder of the GG's RGB output. His page is here. I did, however, have my GG pulled apart and I isolated the composite signal(s) before I came across his page. So, I'll show you what I did to my shiny and cheap (¥800) blue Game Gear:

Step One

Above is my GG, before dissection. (And before I turn the power off, obviously.) To the right: the inside of my GG after I soldered and taped everything down. Sorry, you should use Victor Kemp's page if you need a solder point reference.

Step Two

Then I put the circuit described in Victor's schematic onto a little PCB. Those big blue things are 500 Ohm variable resistors. I put them in so I could adjust the mixing level of the 4 lines that get combined into the video signal.

Step Three

I put in this connector so that I could easily connect and disconnect the video board from my GG. The hole was made with a hot knife from the stove! Yeahhh!	There! Fits perfectly and snugly.	Close the cover and it fits even more snugly. A clean exit wound.

Step Four

Now comes the time to hook up the GG to the TV and adjust the resistors (pots) to get a good, high-contrast image. Sorry, all the pics taken from now on were taken off a TV with a digital camera. I don't have a decent video digitizer. Sorry again.

At the beginning, I used Columns' title screen, as it had a nice gradient in the middle, and I could see what each pot's value change did on-screen. In the picture in the middle of Step Three above, the bottom left pot caused the biggest change in contrast. Also, if the resistance was turned down all the way, the Game Gear's LCD screen would start to lose its own image! To the right of that pot is the next-highest change. In SMS mode, these two solely change the image's brightness (as far as I can tell). The other two pots are minor, but we can see their effects in the following pics.		Yes, that's right. The output from this whole contraption is greyscale ONLY. Sorry, but if Sega gives me a Game Gear with their RGB decoder board, I'll gladly take colour pictures.
Since I didn't know of a game that had a nice, big, greyscale gradient to use for calibration, I decided to hack Tototek's GG menu program to produce 16 greyscale levels. Let's take a look, eh?
		Here we have the greyscale menu; all pots are turned up to maximum.
		The pot on the upper-left gets turned down. This cuts down the levels from 16 to 8!
	The above image is from an emulator.	Turn down the major pot on the lower-left and the contrast goes way up!
Then I changed it to display some primary colours, to check their relative levels.
	An emulator, yesterday.	There are thin vertical lines in the colours, but it's not bad. Red, Green, and Blue seem to have identical luminosity...

And that's all of the technical stuff. Let's go to the PHOTO GALLERY.

It's fun sometimes to hook up my GG to the TV and play it there, perhaps when my eyes get tired from looking at blurry images or something. The quality is not great, never mind the fact that it's in greyscale. The main problem is that this video signal causes bad interference on most TVs sometimes, and even makes it display colours wildly. Through a video digitizer, the GG's output looks really nice -- solid greys. But my digitizer can only capture 160x120 images, so it's useless for games playing or taking pics for this page. Anyway. I guess emulators are good, but don't we all wish for a way to play the REAL THING in colour on our TVs?

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