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Genesis 2:3 - Let There Be (Infra-Red) Light...
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04-07-2025 07:02AM#1
A big, involved, and fairly detailed restoration this one - it's part 3 of the ongoing Sega Genesis II & CD II eBay gamble that I've been detailing (part 1 & part 2 for anyone who is interested). With the Genesis II fully repaired & restored, it was time to turn my attention to the Sega CD II. It was similarly affected by corrosion both inside and out, and was in need of some pretty serious attention in order to make it work properly again. Like the Genesis II restoration, it wasn't at all really economically and/or timewise viable, but, as explained previously, the Genesis II and CD II are two consoles I've a serious and proper nostalgic connection to. In addition, I got them both through a very low eBay offer given the state of them, that it gave me additional motivation to save them. So enough jabbering, and lets see what we're deal with here…
^^ Much like the Genesis II, the CD II is blighted by corrosion and rust stains. The tray area here bears the outline of the metallic plate that usually clips on here, so I imagine that might have been the source of much of the corrosion (externally anyway.)
^^ Under the CD lid, the spindle is borderline growing out like a fungus almost (The Last of Rust…)
^^ Ominous signs as we head towards the inner parts, the CD tray spring is also coated in rust
^^ Underneath, there's signs of rust and corrosion everywhere. Even the rubber feet didn't manage to escape. Was this unit sitting in a pool of corroded water for years??
^^ Under the shell, wow, this is baaaaad.
^^ Mercifully, and inexplicably, the main PCB is actually quite clean. Maybe there's some hope here after all?
^^ Popping the lid back on for a second, and after a bit of back and forth, I get it to boot! Ok, I'm a lot more optimistic now, but there's a LONG way to go before this is classed as restored. To begin with, it's not reading discs (surprise surprise), but now that it's powering on, I don't mind investing some time in it. First order of the day - a replacement laser!
^^ A brand new Sega CD II laser unit.
^^ I obviously need to remove the entire CD tray to replace the laser, so these three plug connectors have to be removed.
^^ Man, that's a sorry sight right there. There's rust literally everywhere….
^^ A shot of the underside of the tray, showing the adjustment pot etc.
^^ The control PCB is actually in a horrid state. Hard to believe this is factory soldering too, it's really really bad.
^^ Disassembly begins…
^^ It's actually not difficult to remove the laser assembly, you just remove the two screws holding the sliding bar in place, and the laser will come out.
^^ A closer look at the control board. Given the nature of the corrosion here, and the obvious level of it, I need to get the multimeter out to verify these traces are still actually conducting.
^^ 4/6 of the traces were borked. Maybe that's why it wasn't reading discs?? I clean up the board a little while the testing continues, and bypass the broken traces with some bypass wires.
^^ With all of these laser units, there's a blob of solder to be removed (it must ground them during transport to protect them) before it'll work.
^^ New laser unit in place, and ready for testing.
^^ I'm not sure this spindle is salvageable being honest, it's so heavily corroded and pitted that a disc won't lie flat on it. I'll try my best to sort it, but I'm not hopeful for this one…
^^ Time to break out the big guns….white vinegar and a long bath….
^^ Not much of a visible reaction when immersed, so I leave it a good hour.
^^ A one hour soak in white vinegar, and a nudge with a cleaning toothbrush wasn't really budging the rust. So I resort to a wire brush attachment on the Dremel.
^^ Meh, it's improved, but still not flat. I'd be surprised if it works tbh…
^^ Bah, still no signs of life re reading discs. I think I need to order a new spindle, and maybe some other refurb bits. Therefore, I'll come back to the issue of not reading discs a little later.
^^ So, first up will be a complete recap. One or two of the caps look a little dry/crusty, so they'll all be swapped out for brand new ones.
^^ Here for example, the cap pad looks like its either been contaminated with corrosion (though no other local signs of that) or else the cap has begun to slowly leak and react.
^^ All originals removed, and the above shows a few of the new ones in place. It's not an easy recap job, as the board is multilayered, and many of the caps didn't want to budge at all. I had to snip some of them, and others needed heat from both sides of the board.
^^ What felt like hours later, and many, many, caps later….the recap is done.
^^ Time to tackle the awful, awful, corroded shielding & associated metal parts next.
^^ I immerse the whole lot in a container of white vinegar, and I leave it all to sit overnight.
^^ The next morning, I go back to it and hit it all with a toothbrush while still in the vinegar. The mess is pretty awful.
^^ It's better, but still a far far cry from what it should be like. No option so….
^^ …but to hit it with some metallic silver spray paint. Ok it's not the shiny original look, but at least now, any remaining corrosion has been neutralized, and covered up. It's at least a lot more visually pleasing to look at. I could also have binned the lot of it given it's mostly unnecessary, but if I can find a way to keep it and as many original parts as possible, I'll definitely try.
^^ With that out of the way, I have another proper look around the mainboard for other outstanding issues. I then notice the Expansion Connector, is riddled in green corrosion. So bad in fact, that it looks like a reflection of the PCB!
^^ I desolder ALL of the many pins…
^^ …and the connector comes out. Glad I did this too, as the underside of it (the PCB side) was filthy and in need of a deep clean.
^^ The green corrosion is possibly only surface level, but it'll need tackling one way or another.
^^ I needed a suitable container for a white vinegar bath, and Nescafe provided.
^^ I then immerse the connector, and leave it a good while to soak.
^^ Much improved. Not 100%, but anything remaining is just stained really, there's no more active corrosion happening now.
^^ While I'm in this area, I see the voltage regulator is pretty caked up in dust, dirt, and flakes of corroded gunk.
^^ I tilt the regulator back a little, and clean the whole area with IPA.
^^ A small blob of new thermal paste will keep the regulator much cooler…
^^ Screwed back in place….
^^ I clean the excess paste away then with a q-tip
^^ The expansion connector pads all cleaned up and the whole area looking a lot nicer now.
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So, next up is to begin the preparations for the Multi Region Bios modification. What this mod does is, if you have a Multi Region Genesis (Megadrive), it'll match the region of the Sega CD to whatever the Genesis is set to. So in other words, if I set the Genesis to be a Japanese region, the Sega CD will boot the Japanese region bios. If the Genesis is set to PAL, the Sega CD will boot a PAL bios, and so on. If it works, it'll be a truly switchless multi region setup, with regional bios screens to match!
^^ This is the Genesis II pcb plugged into the Sega CD. You can see the two wires that originate from the multi region Genesis mod. These two wires will tell the Sega CD what region to boot. The trick here, is to find two Expansion port pins that are unused - this isn't an issue on Sega CD Model 1 boards, but on the Model 2, they're all used. As a result, the only way I could see to do this was to isolate two of the ground pins from the ground plane (there are multiple grounds, so this should be fine), to create to repurposed pins - this is done both on the Genesis II and on the Sega CD II's matching pins. You can see here above, that I've cut the ground trace to the topside pin and soldered the wire after the cut to send the region signal to that pin now instead of ground. I did the same on the pin directly under the board too.
^^ Then on the Sega CD itself, those same pins line up with these two pins, which are again, normally ground. So these pins are also tied to each other, so in total, x4 cuts need to be made on the Sega CD. One cut to separate the two pins from ground, and another cut to separate them from each other. Then do the same on the bottom side.
^^ These are the pins on the underside. Poor pic, but you get the idea, it's the same as the topside.
^^ The first topside trace is cut
^^ The first bottom side trace also cut.
^^ After the remaining two traces were cut (forgot to take pics), we need to look at the Bios chip itself. Specifically, we need to remove it, solder in a a socket, and flash an eprom with a multi region bios image.
^^ The original bios isn't socketed here, so will need to be desoldered.
^^ Done!
^^ …and out comes the chip.
^^ A new 40 pin socket is the order of the day
^^ Inserted, and soldered in. This will make swapping out the bios in future (if ever needed) a lot easier.
^^ I erase a matching eprom (mistake incoming) to prep it for flashing
^^ Now, we need to create the new multi region bios image. So above here, we've all three regions for the Sega CD II, and a duplicate US region. The duplicate is needed to fully fill the eprom chip.
^^ I rename them to make things easier for command prompting.
^^ So we need to amalgamate the four bios files into one single file, the above is the command to do so.
^^ Done, I now have a single file that contains all the three regions.
^^ Blank check to make sure the eprom is fully blank, which it is.
^^ We load up the new multibios.bin file we created….
^^ And we send it over to the eprom then.
^^ All done
^^ We bend up pins 38 & 39 to ensure they DON'T go into the socket, because our two wires from the Genesis II multi region chip, which pass through the now modified Expansion connector, will be wired to these. They'll tell the chip which region/bank to load up.
^^ Aaaaannnddd, I've flashed it to the wrong size eprom chip. Middle age man, the concentration goes!
^^ This is what I should have used, a 27C4096. Not a problem, I'll just reflash the file to this chip.
^^ Done!
^^ Legs 38 & 39 bent up, and wires attached. Ready to insert into the socket now.
^^ I had to bend the legs up almost vertically to make sure they don't interfere with the Expansion port pins, and to account for the shrink sleeve placed on them. Not a problem, the chip is now inserted, pins lifted, wires soldered to them, and routed through the Expansion connector.
^^ I put another short run of shrink sleeve around the bios chip wires in this location, just to protect them against the large heat sink/shield. From here, they run under the board to the pins we've isolated previously.
^^ And done, two wires now coming from the bios chip to the two relevant pins. That connects the Genesis II's region free board, to the Sega CD, through the Expansion port connector.
So what did testing show? Ugh, nothing, it doesn't work! Black screen. After some head scratching, it seems I needed to byteswap the rom image to work in real hardware!
^^ A ChatGPT script written in Python to the rescue here. This takes the combined rom image we created, swaps the bytes around, and spits out a new file for us.
^^ I then flash that new multibios_swapped.bin file to the eprom, and we're good for testing!
^^ Ok, it's working/booting up now thankfully! Red led on the Genesis tells us it's in NTSC-U mode, so the Sega CD is loading up the USA bios….so far so good…
^^ Green LED is PAL mode, and the Sega CD is booting the PAL Sega CD II (Mega CD II) bios!
^^ Orange tells us we're now in NTSC-J mode, and sure enough, the Sega CD is now a Japanese Mega CD II - absolutely delighted with this, it's a very nice touch. You could obviously just use a region free single region bios, but where's the fun in that - having the three appropriate regions feels like a really nice touch.
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After some time has passed, my new parts have arrived that'll hopefully allow me to sort out the CD reading end of things. So let's get to that!
^^ I take the CD assembly back out, and will need to fully disassemble the thing to do this properly.
^^ The 'chassis' itself wasn't spared from the corrosion. It looks horrible, so I'm going to give this the once over too.
^^ An overnight white vinegar bath is the first step. This will neutralise the corrosion, and help me clean it off.
^^ A bit of a slow reaction when I came back to it the next morning.
^^ Scrub a dub dub….
^^ Ugh, a lot of the corrosion has lifted, but the metal is still pretty bad looking.
^^ A bit of brushing with the Dremel, gives us this. It's a lot better, but still not exactly pretty.
^^ I mask off the more important areas of the chassis, and hit it with the metallic silver spray.
^^ Unmasked…
^^ And the underside also done. A huge improvement.
^^ So here's what we've to do. Two brand new motors for disc and laser control. Also a brand new modern spindle, the same type that's used in the PS1. This spindle has three ball-locks that hold the disc in place. The big benefit here, is it's obviously brand new, but it'll allow me to remove the magnetic disc lock in the Sega CD itself…meaning massively quieter disc operation.
^^ Closer look at the new motors. One spindle is longer than the other, and the dimensions of both match the originals perfectly.
^^ Brand new spindle, nice and flat, unlike the original zombified one.
^^ The gears and rubber mounts can take a nice warm soapy bath while I'm swapping the motors out.
^^ Ok, time to get to work. The original motors are on the control board, so will need to be desoldered first.
^^ I got this new solder braid recently, so rather than using the desoldering gun, I'll try this braid out.
^^ The braid works amazingly well, highly recommended. Plus, there's corrosion on this motor that I hadn't spotted before, so I'm delighted now to swap it out!
^^ Job done, quite straight forward really.
^^ Control board now back in place, with the new motor shafts fitting perfectly.
^^ Gears and rubbers all cleaned up, and a nice dressing of silicone grease on the gears and sliding parts.
^^ Shroud and spindle now in place. It's looking so much better, but will it actually work??
^^ Top lid back on for testing…
^^ And magnetic disc lock from the lid is now removed. Awful noisy things, so if this new spindle works, this should be a very quiet Sega CD II!
^^ You absolute beauty! It works! Ok in context, it didn't work immediately. It tried really hard to work with lots of reading and seeking going on. What was needed though was a slight tweak of the laser potentiometer to increase power slightly to the laser. It's also SUPER quiet too with the new spindle!
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Almost there now. One last little mod I want to make.
^^ The 3.3v battery that keeps the game saves alive in SRAM, this has to go. It's the original battery, and completely flat too.
^^ It'd actually begun to corrode too, which I hadn't noticed earlier. Glad to remove it!
^^ Area treated with white vinegar to neutralise the acid, and then cleaned again with IPA.
^^ The SRAM chip where the game saves are stored. We can do a little better these days can't we? What about an FRAM mod, which is a non volatile form of ram….no battery needed!
^^ Area masked off with kapton tape, as I'll be using hot air to remove the old chip.
^^ It took a while, but the chip eventually agrees to lift out.
^^ The pads all wicked clean, and wiped down with IPA.
^^ The Ramtron FRAM chip. It's pin compatible with the old one, so it's just a straight swap. You CAN use a bigger capacity FRAM chip if you want, but you need to use switches to bank swap so I'm not going to bother. I think there's also a bios mod to allow larger capacity chips too, but it has it's own complications regarding regions etc, so I'm just going for a stock sizing here.
^^ And done. All legs checked with continuity to ensure they're soldered correctly too.
^^ Now that disc reading is fixed, we can access the memory manager (bizarrely you can't access this menu on the Sega CD II unless there's a game disc in place.)
^^ Ok, the memory is being detected and the machine is telling us to format it….good signs
^^ We hit format…
^^ Noice, it formats with no errors etc.
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Ok, that marks the end of the repair work…I need to just add the finishing touches now.
^^ This is going to be hard to clean. I can't use anything abrasive to remove the stains, as it'll look absolutely cack then
^^ I'm going to to try localise a white vinegar treatment on the affected area.
^^ Slightly better, but it still looks bad. I can only thing of one, final, drastic action which has the ability to look really well, or really really bad…
^^ Yep, I'm going for broke here….I'm going to try some black spray paint on it. The ONLY reason I'm willing to chance this, is because with the Genesis II in place, this entire area will be covered. So I figure it's worth a gamble.
^^ Ok, we're done. Time to let it dry.
^^ D'ya know what? I'm actually really, really, please with the end result. It's a million times better.
^^ Reassembly begins…
^^ Main board back in place.
^^ Top shield and laser unit resting in place.
^^ Some brand new M3 screws to hold everything in place. Many of the original screws were missing.
^^ Everything locked down.
^^ Time to test these different regions. This is a PAL game…
^^ We set the Genesis II to for PAL mode…
^^ The PAL Mega CD bios boots…
^^ And the PAL game boots!
^^ Let's try a Japanese game…
^^ Japanese BIOS boots…
^^ And Japanese games boot!
^^ The FRAM mod is storing data perfectly…
^^ Even after a power off, and region swap, the Sonic CD data is retained - no more battery needed! There's no point testing the US discs and bios again as I know they also work from previous testing.
^^ A final exterior cleaning of all nooks & crannies…
^^ And it's done, it's finally done. I can't say how happy I am to have saved it, it really was an absolute mess.
On the downside, I can't leave it like this can I? Do I now need a switchless region modified Genesis 32X to complete the ToP?
^^ Ugh, there's a revalation….there'll be one more part to tell in this story….
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