Genesis 3 tear-down and documentation (56K FAIL)

[robm]

I've had a Genesis 3 laying around for a while, and in response to DNT's wishes, I have torn it apart tonight to reveal it's tiny secrets.

Well, really just to show how small they really are - and to document necessary things for making these portable, like pin-outs and such.

Audio/video pinout:
Red: RGB Red
Green: RGB Green
Blue: RGB Blue
Brick: 5v
Pink: Sync
Yellow: Composite video
Cyan: Mono audio, or left audio
Purple: Right audio

Controller pinout:
Keep in mind, the button description is purely for novelty, you will need to solder the wires from the Genesis controller directly to the solder points shown here. This is because the Genesis controller uses a multiplexer to eliminate the number of wires required for the buttons, by combining the select pin with another button.

Time for the tear-down. Here's the front:

Here's the back, four screws to remove at each corner:

Here's the inside, with the nice shiny shield with four screws to remove:

Here is the shield removed, with three or four screws to remove the motherboard from the case:

There it is, easily palmed in my hand:

Pinouts and further documentation soon to follow.

 

[robm]

And just for posterity, a better pic of the heart made of PCB trace:

Cracked me up for some reason, probably for it's obviously-drawn-by-hand-in-Eagle-by-Sega-engineer-on-purpose charm.

 

[bentomo]

Lol, I've never seen rounded traces.

 

[snowpenguin]

He wanted to make sure all of us modders knew that Sega stood for HUGS NOT DRUGS!
YA!

 

[Basement_Modder]

Lol, I've never seen rounded traces.

Really? Almost all pre-1985 electronics have them.

 

[robm]

Which makes this piece of 1998 technology even more amusing. Especially when combined with ostensibly NO other curved traces on the rest of the board, for the most part.

 

[XCVG]

You said on the A/V pinout that there is mono audio and right audio, is the mono just left channel or is it pre-mixed?

 

[robm]

In theory, the G3 isn't capable of stereo output - the left channel, if you look at the trace, just runs straight on through to the mono channel. I haven't trace it yet to see if there is, in fact, a right-channel audio output.

 

[neverused]

this may help:
http://www.freewebs.com/vgmods/segagene ... aitons.htm

 

[neverused]

I just got a Genesis 3 too and thought this may be helpful:

One interesting note is that my board lacks the heart shape robm's board has...

 

[eurddrue]

Lol, I've never seen rounded traces.

Never looked at an atari controller? What are the modders of this world coming too!?

 

[zeturi]

I thought that the genesis 3 required modification for rgb... http://www.gamesx.com/rgbadd/genesis3.htm

I also have the same board as neverused.

 

[robm]

As the G3 takes the standard 9-pin connector, the pins required are there - they just aren't actually connected on the console, kind of like the R-channel audio. It's there... but doesn't work. The G3 was mono-only.

However, yes, the console can be modified to output both S-Video and RGB video.

Thanks, Neverused, for the rulered pic

 

[robm]

This board has excellent opportunity for reduction. Without any MAJOR component relocation, the board can be reduced to a 4.5"x3.5" footprint.

Here are the lines one would cut:

Close-up of the cart connector slot area:

And close-up of the controller port area:

Edit: Oops. Obviously, one would not cut off one of the legs of the regulator when reducing the board size. So ignore my lower-left-corner cut line mistake.

 

[zeturi]

I attempted an identical cut-down of the board like that, but isn't working. The only thing I left on was the place to connect the cartridge. I'm just hoping that I only cut away too much ground, and that I can reconnect the trace elsewhere.

 

[robm]

If you cut along those lines, there should be no problem - got pics?

 

[zeturi]

Hold on, I'll have them in about a half hour...

Okay, here we go. I relocated all my capacitors, and soldered in a game. (My cart slot wasn't working at the time). All of my stuff worked then. But I decided to cut my motherboard down, and now blank screen.

And yes, for the top picture I know the capacitor is screwed up in the top-righthand corner. But it worked even with it like that. It stopped working only after I cut the board. The game also isn't soldered in all the way, because I was in the middle of redoing it for a third time.

 

[robm]

Heh, you've got the newer, non-heart-shaped board too.

Anyway, I see two areas of interest. The 7805 regulator looks a bit distressed; what did you use to cut the board down? If you used a high-speed cutter, like a Dremel, that can heat the board up hot enough to melt solder. Zooming in on the backside, it looks like the connections might be ok... but then, they might not be. One of the pins looks like it's come out almost completely. Check your connections with a voltmeter.

My next area of concern... did you remove the reset switch before or after you cut the board down? If you removed it after you cut the board down, that may be an issue there, depending on what type of switch the G3 used. If it's an interrupter, then that's your problem right there. If it completes a circuit when pressed, then not.

Edit: Just checked out mine, it shorts a circuit to ground, so I'm going to go out on a limb here and say that's not your problem.

I would take a voltmeter and see what's going on with the voltage regulator, make sure you're getting good ground, input, and output voltage. If you're getting all three, then the problems probably something to do with the cart connector. If you look at the backside picture of the cart connector of my G3, on the top row to the left, second pin from the left, there is a trace that wraps around the number 1 pin that traces to a capacitor, the one next to the IC3 label. I'm going to say that's a possibility. No big deal if you've cut through it, though. I can't tell from your pic if there was a trace there or not.

Edit #2: No trace was there, just looked at Neverused's backside pic. Check out that regulator, then get back to me.

 

[themadhacker]

perhaps the gnesis 3 has hidden layers?

 

[robm]

Nope, it's definitely just two layers.