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Neo Geo CD - A Junk to Joy Adventure
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31-12-2023 8:48am#1
My final repair/restore of 2023, and it's definitely an interesting one. I'd bought a few bits from a Japanese seller on eBay a good while back, and to sweeten the deal, one of the items was a junk-condition Neo Geo CD. It wasn't something I set out to buy, so I figured I'd just see it it powered on and if it didn't work, I could just move it on for cost. Well, it arrived, and sure enough it didn't power on (and was in pretty dire condition.) I listed it on Adverts, because my to-do pile is already massive, and because this needs time and a proper diagnosis, I was happy to sell it on. There wasn't much interest, naturally enough, but I thought €75 was a fair price for someone willing to take a gamble. No takers. So I said ok, I'll sit down and investigate this properly....wouldn't it be nice if I did fix it and I ended up with a working Neo Geo CD after all?!
^^ It's original condition. It's absolutely filthy, a little hard to tell here but the plastic texture is caked with grime. The CD tray lid has been butchered open, cracked, and sits in place only on one side.
^^ The two rear screws are suspiciously corroded.
^^ Pretty filthy under here too.
^^ The CD tray lid hinges on one side only (the other side's gearing/cogs are missing completely), and at least the latching mechanism works and holds it in place.
^^ A power on test shows no life whatsoever, completely dead.
^^ Hmm. I better open this up and see what awaits me....
^^ Yikes, well, that explains the no power. There's obviously been liquid ingress at some stage, and the power supply got it in the neck - several components are absolutely fried - ouch!
From here I'm in a little bit of trouble. There's a resistor, a capacitor, a diode, and x2 voltage regulators fried. The regulators I'm fine with because I can see they're standard 5v regs. The other three components though, they're a different story. They're exploded, and as such, there's no markings to read off. I scoured, and I mean SCOURED the internet hoping to find schematics of the power supply/av board. I found some, but nothing that could tell me what replacement parts to buy. Next step was to maybe try find a replacement power supply/av board....nope, nothing. The only other hope was to buy another junk Neo Geo CD and salvage the power board from it, but when pricing them, you're looking at ~€150'ish delivered for a non working console....so that's out. This is looking like the end of the road...
I did try one last thing. The frankly brilliant Luke from Console5 has a comprehensive technical wiki for many many consoles. Maybe he had some info? I could see he had this page at least - https://wiki.console5.com/wiki/Neo_Geo_CD_Toploader so maybe he had more info if I asked him? I fired him off an email, fully expecting that I would remain at a dead end....but within a few minutes, he had messaged me back looking for more info. I sent him on the model number of the board, and like a ray of light, he was able to send me reference pics and values of the missing components. The guy is beyond helpful, and if anyone is ever looking for parts from the States, I'd strongly urge supporting people like him. Luke, if you ever read this, thank you again, seriously.
^^ A few days later, my order from CPC Ireland arrives. New signal diodes, resistors, capacitors, and voltage regulators. Time to get to work!
^^ The voltage regulator bolts are badly, badly corroded. It's very odd though the corrosion is so localised.
^^ So corroded in fact, that one of them sheared off.
^^ The days of regulating voltage for these lads is definitely over. Yikes.
^^ Yikes, what a mess. Turns out the info on that cap wasn't lost after all. There was obviously a huge arcing situation here, there's a small hole burned through the board right beside the damaged capacitor. It looks like water/liquid bridged the capacitor and the regulator, which burned the board and took out the other components before the fuse eventually tripped.
^^ Capacitor out.
^^ The corpses of the resistor and diode out.
^^ That's all five components out. There's a bit o' cleaning to do here.
^^ The via for the diode was filled with solidified gunge. I was able to poke an old resistor leg through it to clean it out.
^^ After an IPA scrub with some q-tips, it looks a little better. I can see what I'm doing now at least. Any marks left on the board here are baked in, but all the rusty residue is cleaned up, and I'm ready to start replacing components now.
^^ I got the Gadunkmeister himself, @Steve X2 to print me up some component leg bending tools. It takes the guesswork out of making bends, and gives a nice pleasing finish.
^^ Ok, one component in place now (D5, small signal diode), x4 more to go.
^^ Resistor R33 done.
^^ Next up is the capacitor C17. However, there's a hole blown through the pcb. I don't want to just throw the capacitor into the hole, so I'll at least give it a layer of kapton tape. There's no issue here really, I just want to cover the hole incase anything ever rolled into it (you can see the eyelet from the topside, so there's exposed current there.)
^^ Done.
^^ Last two components now, the x2 voltage regulators.
^^ This pic is some time later, when some new minty fresh M3 nuts & bolts arrived and I could secure down the regulators.
Of course, none of this is to say the console will work now. All I've done is replace what I could see was visibly fried/corroded. There's always the chance that important logic chips were cooked, or other components were fried further along the power rail that I just don't know about. But it's a start, so it's time for a test.
^^ To my surprise, and delight, it actually turned on! Yus!!!
From here, I can set about cleaning it up and restoring it into a much better state. There's some issues with it still at this point, CD's don't appear to be spinning for a start, but for now, it's time to CLEAN.
^^ First thing's first...full disassembly and warm soapy bath. A scrub down then with a soft brush to remove the caked in grime will help.
^^ Two internal screws from the power/av board, and the two rear screws which were corroded, and all having a nice 30 minute bath in WD40 here. This will soften the corrosion on them, I can then wire brush them, and spray paint them. Obviously it's easy to just throw replacement screws in there, but if I can possibly salvage as many bits as I can, then that's the goal.
^^ Multiple WD40 baths to soften the corrosion, and plenty of wire brush treatment, and a large amount of the corrosion is gone. What remains here is fused to the metal, and I'd need a rotary tool to grind off what's left. That's a tool I've done without for the most part, I really must pick up one. I might grab one and revisit this at a later time, but for now, this is ready for painting.
^^ And done. Not perfect by any means, but MUCH better.
^^ The CD drive ribbon cable appeared to be mangled. I tried straightening the pins out and securing with kapton tape, but it didn't work.
^^ Same with the controller board, you can see the lifted pin on the end.
^^ Replacement ribbons from eBay will do the job nicely.
^^ The lid of the CD tray is a lost cause. It's missing its entire side gear, and to fix this would require me to own a 3D printer I feel. I'd have to take specific measurements, and make a bespoke fitting to be plastic welded into place. There's far too much guesswork to commission this out to someone. I tried various fixes, with all varying degrees of jank...but nothing worked. The absolute best I could do was use a small piece of Sugru, and mold it into the hole shown at the bottom of the tray here. It'll at least hide the fact that someone tried to butcher it open.
Unfortunately the replacement CD drive ribbon didn't solve the drive not spinning discs up. It does engage the laser, and that attempts to focus, but the disc won't spin. I suspect the motor is burned out, so maybe I could revisit that again in the future should I feel the need to. Will I though? Probably not. Sure, it'd have been nice to have the drive work, but the Neo Geo CD is NOTORIOUS for its slow loading speeds. Thankfully, today, there's a better option.
Enter, the Neo SD Loader....
^^ Designed by Furrtek, it's an ODE for the Neo Geo CD. The controller board clips on over the main CPU, and the daughter board screws to the cd drive controller board. They both get linked with the ribbon then. In terms of soldering, there's a small bit to do, none of it particularly difficult, but one part involves lifting a pin on an IC so that obviously needs care and attention.
^^ CD Audio connector soldered into place. You can see here these cheap connector arrived broken, and became a bit of a headache for me later on.
^^ The Neo Geo CD motherboard. Despite the corrosive carnage seen earlier, the board itself was spared. It's in mint condition. Connector CN3 here is the area of interest. This is where the CD audio is piped out of. On a stock console, it goes from CN3 to the connector on the power/av board, and out to the TV then. We need to tap into this from the underside, and patch it onto the Neo SD Loader board.
^^ Wires cut to length (I followed the guide in terms of measuring these, and they still ended up far too short....strange one. I redid them later on, just with longer cables.)
^^ Pin 12 on the IC lifted. You then solder a wire from the pad on the board, and a wire from the lifted pin, over to the Neo SD Loader. That's five wires in total. The wire here is a little big. If I was doing it again, I'd use a smaller wire.
^^ Ready to mount the Neo SD Loader now. The white arrow on its connector, must align with Pin 1 on the CPU.
^^ It's a nice snug friction fit, and seems quite solid once in place.
^^ All five wires soldered to the Neo SD Loader. All that's left now is to attach the CDDA connector, that connects the power/av board to the Neo SD Loader.
^^ aaannnndddd of course, it's not long enough. I need to extend this. I really don't want to be cutting wires etc though, so I'll run my own cables from the underside of the connectors on the power/av board, and use the existing white clip seen here.
^^ This one. I'll just remove the wires from it, insulate them and tape them away, and use my own (longer) cables instead.
^^ Done. This way I keep the console as original as possible, without having to cut cables. I'll just insulate the old ones and tuck them away.
^^ It's still kind of awkward, you have to pass the CDDA cables through the shield, and then clip them into place on the Neo SD Loader. The white connector that came with the Neo SD Loader though, is a piece of crap. It's barely holding the CDDA connector. I'm just test fitting here, the small ribbon at the funny angle should be routed through the shield via the hole on the left hand side (I done this correctly later on.)
^^ The Micro SD board is screwed into place on the underside of the cd drive. It allows the micro sd card to peek out through the grilles of the console, no drilling or cutting required! I did have to use a flat file to remove maybe 1/2mm of plastic in the grille. Once done, it fit through like a glove, and you can't see any filing from the top side.
^^ Hi there!
^^ Time to fit the console halves back together. It's slightly fiddly now, as the ribbon from the Neo SD Loader has to be connected while holding the halves nearer to each other.
^^ Accessories needed for testing, an RGB scart cable and a well regarded replacement power supply (no step down needed!)
^^ A power on shows the Neo SD Loader dumping and patching the bios...so far so good...
^^ Three green flashes....very good...
^^ Boom! It works!
^^ I can now change the region of the console if needed, back up game saves, restore game saves, etc etc.
^^ You can reboot the console with the Neo SD Loader disabled, and the internal CD drive enabled if you want to play from disc.
^^ It works (with an issue I'll explain below.) The loading speeds are dramatically improved, and I mean dramatically. It's not far off cart speeds I'd say.
There's two issues though. 1) Joypad port 1 is missing directions and button presses. 2) There's no music playing. Lets investigate!
^^ Taking it all back apart, I'll look at the controller issues first.
^^ Port 1's issues thankfully being very very obvious here. Years of rough connects/disconnects of the controller have obviously taken their toll. Several traces are broken.
^^ Exposing the traces, I can test. Several pins have obviously lost continuity, others are ok.
^^ Apologies for the blurry pic. I didn't want to run several patch wires, so instead I tried just flowing solder from the pins to the exposed traces, thereby bypassing the cracks. If it gives issues in the future, I'll run wires, but for now, the multimeter is very happy that all pins are now connected to where they're supposed to be.
^^ Issue 2 and the no music was another obvious one, that crappy connector just wasn't holding the CDDA connector properly. I took the connector off, and soldered wires directly to the pins.
^^ Then on the other side of the shield, I fit some dupont connectors on the ends, which mean I can now connect/disconnect the AV board without having to remove the whole shield. The benefit here is a rock solid connection also. I insulated these and grouped them together also (not shown.)
^^ Time for some Metal Slug. You can see the loading screen animation is basically blurred, because it's moving that fast. Also shown is the in game Neo SD Loader cheat and config menu (controller hotkey to access it.) I was also able to complete the level, because the controller is now perfect!
^^ Job done. I'm absolutely delighted with it, and very glad I didn't sell it on for peanuts now. It's a nice feeling bringing a machine like this back from the bin, and back into active use. I've never owned an Neo Geo, until now. Ok it's no AES, but with the ODE, it's damned close. As a console, it's actually a gorgeous looking machine. Time to explore its library!
Two issues remain, the cd tray lid, which is defunct now due to the Neo SD Loader, and the cd drive not spinning discs, also defunct due to said ODE, but otherwise, it's ready to rock n roll.
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