Making SEGA Genesis cartridges

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pbj:
So, I figured there had to be a quicker way to clear clogs, and found out this works really well. Keep the flame on the tube until you burn your thumb, and then turn on the vacuum. You'll watch a molten turd go flying down the tubing. Quite satisfying.

I have officially thrown in the towel on depopulating EA pcbs. I don't know what the hell kind of solder they used, but it's taking me over an hour per cartridge to get the holes clean. Oddly, it's the same pins that are problematic. Maybe the carts ran hot and quietly smoldered? My best strategy has been to do as many pins as I can, then break off the ROM chip (oh no, RIP Madden 93) and individually do the remaining pins. THEN I put my tubing on the exhaust port of the vacuum and blow the remaining solder out of the back of the PCB. THEN I take a thumb tack and manually force it through the holes. One by one by one by one by one.

So, enter this reproduction board:

https://www.tindie.com/products/ryanbatesrbg/repro-pcb-for-sega-genesis-mega-drive-eproms/

I emailed the creator and he had a few in stock. I ordered them all. I will be placing an embarrassingly larger order soon.

He did a very, very nice job on these PCBs. You can use surface mount or through hole parts. The chips drop right in. He put the 2MB / 4MB jumper on the back of the board so you can still change it when you make a mistake and have already soldered the EPROM on. (there's another prominent seller that puts the jumper under the EPROM which is the dumbest design I've seen in ages. It's a breathtakingly stupid setup) The connector edge is beveled, the corners are rounded. Every complaint people have about other repros has been addressed with these.

Here's Metal Dragon, a 4MB eprom, using actually correct parts values for the capacitors (47uF 16V for the electrolytic and 0.1uf for the other one).

And here's Mutant League Hockey, a 2MB chip, and "eh, kind of close enough" parts. 2x10uF caps or something like that and I can't even remember what the ceramic capacitor is.

And the PCBs drop in beautifully in both EA and Sega cases:

And here's where I confess I've made a rather expensive and large purchase of games. So... whenever any of you is ready for some Genesis games, please get in touch.

:cheers:

BadMouth:

--- Quote from: pbj on May 09, 2022, 11:39:53 am ---So, I figured there had to be a quicker way to clear clogs, and found out this works really well. Keep the flame on the tube until you burn your thumb, and then turn on the vacuum. You'll watch a molten turd go flying down the tubing. Quite satisfying.

--- End quote ---

This looks like some hardcore drug thing that I'm too naive to know about.

I've been enjoying your cartridge making venture. :cheers:

pbj:
I’ve been buying boxes of ---steaming pile of meadow muffin--- just to see if I still feel lately.

Got real excited… a Tengen cartridge with no label and the serial number on the chip couldn’t be found on Google. Maybe it was some variant of Grind Stormer and I was gonna be famous.

Tengen pcbs are absolute crap, btw. Reflowing the pins got nothing out of it, so I popped the chip…about half the solder pads were destroyed in the process, too.

Put this turd in my tester boards and nothing, so pulsed some voltage through each pin doing a diode check.

And here we are…

So, who knows.. maybe this is some earlier variant. It wasn’t released until 1994 by Time Warner, and my PCB was labelled 1993 Tengen.

:timebomb:

bobbyb13:
I love this thread.
At the rate you are going you are bound to start finding some really weird ---steaming pile of meadow muffin---.
I'm looking forward to it myself.

pbj:
This one had been vexing me for awhile. There’s a few 3MB games that are split across two 2MB chips. The ones of note are Sonic Complete, Beyond Oasis, and Phantasy Star 4. The worthless ones are World Series Baseball 95 and 96.

You actually split the rom into two chunks - the first 2MB and then the last 1MB. Put the 2MB chip in the bottom slot, 1MB in the top. Every pin should buzz out continuous to each other except for Chip Enable.

Here’s my beast of a test cartridge. Didn’t work at first, it was a bad connection on the top chip pin Q15A-1. I was getting all kinds of weird behavior until I went pin by pin and compared it to an unmolested board. Anyway, scrape scrape on the solder mask and dragging a drop of solder down the trace and we’re good to go.

And here’s World Series Baseball turned into something I might play some day. Couldn’t afford this in the 90s….

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