Awesome post! Super cool to see your original mod work and your update! Always fun to mark your progress. I need to do a region mod to mine as well.
SEGA Mega CD Model 1 Refurbishment:
I recently purchased this PAL Mega CD and like with the Game Gear these are notorious for having bad capacitors that should be replaced, so a refurbishment was in order:
SEGA Mega CD 1690-18 Recap:
After opening up the Mega CD and gently removing both the ribbon cables I was able to remove the main motherboard PCB of the Mega CD:
Since the ML2016 T25 Rechargeable Battery (25 mAh) was dead and because I wanted to socket the BIOS chip I removed both of them along with all the capacitors in one go:
It was hard to notice until the capacitors were removed but the majority of the SMD capacitors had been leaking and causing some corrosion to the contact pads and especially bad are that the C41 and C47 had caused some corrosion to occur on some of the BIOS via’s:
SEGA Mega CD Motherboard PCB Capacitors
C41 10µF 16v SMD LEAKING!
C42 10µF 16v SMD
C43 10µF 16v SMD LEAKING!
C44 10µF 16v SMD
C45 10µF 16v SMD LEAKING!
C46 10µF16v SMD LEAKING!
C47 10µF 16v SMD LEAKING!
C48 10µF 16v SMD
C49 10µF 16v SMD LEAKING!
C50 10µF 16v SMD
C51 100µF 6.3v
C52 100µF 6.3v
After measuring the original SMD capacitors I was able to find some Nichicon UWX1C100MCL2GB SMD capacitors that are suitable drop in replacements. Sadly these parts are now EOL so stock is limited.
Since these SMD capacitors are tiny (only 3mm Diameter x 5mm Height) they are difficult to work with, so unless you are a bit OCD like me it is probably best just to go with mini electrolytic replacements.
NOTE: Care needs to be taken when removing and replacing the capacitor at position C51 because a resistor is soldered to it underneath the PCB.
I also removed all the capacitors from the Power PCB:
SEGA Mega CD Power PCB Capacitors
C1 10µF 16v
C2 10µF 16v
C3 10µF 16v
C4 10µF 16v
C5 10µF 16v
C6 10µF 16v
C7 10µF 16v
C8 10µF 16v
C9 10µF 16v
C10 10µF 16v
C11 10µF 16v
C12 10µF 16v
C13 10µF 16v
C14 10µF 16v
C40 100µF 6.3v 105c
C41 100µF 6.3v
C42 100µF 6.3v 105c
C43 100µF 16v
All the capacitors on the power board tested good with only a couple around the voltage regulator heat sink having any slight variance but well within acceptable he 20% tolerance.
There are also a few capacitors on the optical drive PCB but at this moment in time I am not going to touch them while the optical drive is functioning.
My take away from this recap is that you can probably ignore recapping the power board but you should 100% remove and replace all the original 10µF 16v SMD capacitors as soon as possible!
I now soldered in a socket for the BIOS chip and re-assembled the Mega CD for a quick test:
and everything was working as expected!
Modding the Mega CD for Multi Region BIOS loading:
With the original BIOS removed I now needed to dump its data contents:
To do this I inserted the BIOS Mask ROM into my TOP3000 universal programmer and set it to 27C1024:
As with SEGA Mega Drive Mask ROM’s the dumped data needs to be byte-swapped to be readable:
After byte-swapping my BIOS dump I got a CRC of: 529ac15a which is identical to other PAL Mega CD 1 BIOS files you can find preserved online.
At this point I could have just burnt a modified universal SEGA Mega CD BIOS. However, there are apparently some minor and very trivial issues with doing that and since my Mega Drive is region modded already I decided I would create a multi-BIOS that would change the Mega CD region based on what region my Mega Drive is set to.
For this I needed to use a 27c4096 EPROM which could hold all three region BIOS ROM’s and use its bank selecting legs 38 and 39 to toggle between them.
This would be achieved by connecting leg 38 to JP3 or JP4 (video) on the Mega Drive and connecting leg 38 to JP2 or JP1 (language) to leg 39 as follows:
|DATA BANK||LEG 38||LEG 39||REGION|
|BANK 02||+5 Volt||Ground||JAPAN|
|BANK 03||Ground||+5 Volt||PAL|
|BANK 04||+5 Volt||+5 Volt||USA|
With this figured out I obtained the original USA SEGA CD BIOS and a Japanese Mega CD BIOS from online and byte-swapped them ready to be used.
Then in BINman I loaded them into each file slot in the correct order along with my original PAL BIOS dump:
and then combined them altogether:
This gave me a 4Mbit file with the CRC of ffa52927 that was ready to be programmed to the 27C4096. Leg 38 and 39 then needed to be bent upwards before being inserted into the BIOS socket:
We now need to make a connection from the Mega CD to the Mega Drive utilizing some unused pins on the expansion connectors.
- Expansion Connector PIN 4 needs to be connected to LEG 39 of the 27c4096
- Expansion Connector PIN 6 needs to be connected to LEG 38 of the 27c4096
NOTE: After doing this make sure to bend legs 38 & 39 down the outside of the socket otherwise they could potentially short on the metal shielding when everything is put back together.
We now need to look at the interconnecting piece of the Mega CD:
This needs opening up:
The Ferrite bead around the PCB needs to also be removed which just clips together:
On the reverse of the PCB carefully lift up the ceramic capacitor that is in the way and solder wires connecting expansion ports pin 4 and 8 between both connectors in parallel:
With the wires in place you will not be able to re-assemble this interconnect and we need to modify its housing slightly by filing a 10mm wide space with a 2mm depth at around 12mm from the left hand side:
The Mega CD now can be re-assembled.
Finally on the Mega Drive side we need to solder two wires between the expansion connector over to the JP jumpers:
- Expansion Connector PIN 4 needs to be connected to either JP1 or JP2
- Expansion Connector PIN 6 needs to be connected to either JP3 or JP4
With everything put back together and hooked up:
Mega Drive region switch set to PAL:
Mega Drive region switch set to USA:
Mega Drive region switch set to JAPAN:
NOTE: Switching Mega Drive regions while the Mega CD is powered up is not advised and can lead to the Mega CD crashing. So Power off the Mega Drive before changing regions.
Replacing the Mega CD Internal Battery:
In the previous post a few of you might have wondered why I didn’t have any mention of replacing the soldered in ML2016 T25 rechargeable battery (25 mAh).
There is a good reason for that and I wanted to create a separate post dedicated to the Mega CD internal Memory and rechargeable battery circuit.
Unfortunately ML (Lithium Manganese Dioxide) type rechargeable batteries are no longer produced and even worse the ML battery charging circuit is not compatible with the available alternatives (LIR and VL).
This leaves us with EOL stock that is running out and has a shelf life of about 10 to 20 years.
ML2016 T25 “tabbed” batteries are already very difficult to find in the wild with non tabbed ML2016 batteries being a little easier to find but getting expensive and require a 16mm coin battery holder that are not themselves that common either.
ML2032 non tabbed batteries on the other hand (which are used in Dreamcast consoles) while also EOL still have a fair amount of stock available in the wild and is the same size as the common CR2032 so a coin battery holder is easily obtain cheaply.
ML2032 batteries also have a higher 65 mAH capacity so they will last longer between charges.
So I bought some ML2032 batteries and soldered in a CR2032 coin battery holder:
NOTE: It doesn’t matter if you can’t solder the positive terminal of the battery holder into both the old T25 positive via’s on the PCB. You only really need one to be connected.
Due to the lack of space around the position of the battery on the PCB it is likely you will need to cut away a little bit of the metal shielding to get it to sit flush again:
In the future when the stock of ML batteries is exhausted we will need to use a diode to disable the charging circuit and then use CR2032 batteries which don’t look like they will be disappearing any time soon and having a compatible battery holder in place already is nice.
SEGA Mega CD Internal Memory Repair:
Initially my Mega CD was saving to internal memory just fine but a few days of use later my saves were gone and the ML2032 battery I had inserted was exhausted.
After placing in a new battery the internal memory was incorrectly reporting it had 21885 blocks of free memory:
But it was refusing to format or save:
When I opened up the Mega CD and was able to test the battery with my multi meter while it was turned on I found that the battery was not charging at all and was draining at a rate of 0.01v per second.
THIS IS NOT NORMAL!
The battery charging circuit was obviously not working.
The Fujitsu MB3790 at position IC6 is responsible for providing power to the SRAM and for charging the ML battery and upon closer inspection of this IC we can see the top of the IC is burnt which is a common sign that the IC has gone bad and is over heating:
However, even without a battery, while the system is powered on we should still be able to temporarily save to the internal memory so it is likely that when the charging circuit went bad it also damaged the SRAM which is a Fujitsu MB8464A-10L.
In the arcade domain Fujitsu IC have a bad reputation of going bad after decades of use and unfortunately for us SEGA decided to use a lot of Fujitsu chips within the Mega CD.
The SRAM used by the Mega CD for internal memory is located at position IC16 and is a 8192x8bit (64Kb) CMOS SRAM in SOP28 form factor with the following pin out:
Since I wanted to find a more reliable non Fujitsu replacement for the SRAM, using the pin out above I was able find a suitable compatible replacement Hyundai HY6264ALJ-10 SRAM to purchase.
Using my hot air station I removed both IC6 and IC16:
The removed faulty IC:
Using de-solder braid I then cleaned up the left over solder from the pads:
I then carefully placed the replacement SRAM IC in position with tweasers:
Using a T18-C2 soldering tip I tagged down the top right and bottom left corners of the IC to hold it in place:
This was repeated for the IC6 replacement and then using drag soldering both IC’s were soldered down:
Complete view of the PCB with the new IC in place:
After re-assembly the ML battery now charges correctly and the internal memory now fully functions properly:
SEGA Game Gear (837-9130) 1 ASIC Refurbishment:
I was recently able to pick up another Game Gear in a bundle from a dumpster diver:
As expected the Game Gear has issues, but at least it powers up and has sound (albeit very low volume):
At the bottom of the original Game Gear screen you will find three IC that are embedded within the plastic housing. These IC are LCD driver chips and if their internal connections start to fail you will get a dark 1/3 portion of the screen per failed IC.
Pressing down hard on the center IC removes the dark section of the screen:
However, as soon as you remove pressure the middle section of the screen goes blank again. You can try hot air to try to re-flow the internal connections but unfortunately this was not working for me and coloured vertical lines on the screen usually mean a new screen will be required anyway.
Checking inside we can see some previous liquid ingress damage, fortunately without any corrosion:
So this goes onto my workbench for a recap, screen replacement and general clean up:
Motherboard Capacitor Summary:
C1 - 33µf (6.3v) ~ TESTED: 490nf and LEAKING
C4 - 10µf (6.3v) ~ TESTED: 9.01µf
C11 - 10µf (6.3v) ~ TESTED: 6.5µf
C14 - 10µf (6.3v) ~ TESTED: 10µf
C42 - 10µf (6.3v) ~ TESTED: 10µf
C43 - 22µf (6.3v) ~ TESTED: 7.5µf
C45 - 4.7µf (35v) ~ TESTED: 4.2µf but LEAKING
C48 - 68µf (6.3v) ~ TESTED: 0.88µf and LEAKING
C49 - 100µf (4v) ~ TESTED: 126µf and LEAKING
C54 - 0.47µf (50v) ~ TESTED: 2.48µf and LEAKING
C55 - 0.47µf (50v) ~ TESTED: 3.10µf and LEAKING
C68 - 100µf (6.3v) ~ TESTED: 122µf
Power Board Capacitor Summary:
C5 - 22µf (35v) ~ TESTED: 23µf but LEAKING
C11 - 100µf (25v) ~ TESTED: 117µf
C13 - 820µf (6.3v) ~ TESTED: 858µf
Audio Board Capacitor Summary:
I was unable to test any of the 5 capacitors on this PCB because they were all BADLY LEAKING electrolytic fluid and I didn’t wish to risk damaging the solder pads so I used flush cutters to cut the capacitors clean off and only then removed the remains of the smd capacitor legs.
I then had to resort to using a Fibreglass pen to clean up corrosion:
After everything was re-capped I tested the Game Gear again, but it was not powering on…
I found the issue was that the 1.28v supply wire was sometimes shorting to Ground inside the connector:
Because the short was inside the connector header I had to cut it off and re-solder the wires to the motherboard manually, which fixed the problem and the Game Gear now powered up again.
I then removed all the no longer required components for a new screen installation and replaced several SMD components using my hot air station as the new screen requires some different resistor values:
Replacing the Screen:
I really wasn’t willing to pay the price of another genuine McWill Game Gear Screen and I knew Chinese clones of it had appeared and were available to purchase for up to half the price.
While looking on AliExpress I came across a Funny Playing Version 2.0B Clone screen that advertised among other things:
- Power saving design with DC-DC power supply chip.
- Adjustable Brightness Control
Which got me intrigued as the genuine McWill does not feature any of these and this appeared to be a dubiously “improved” version and not a mere clone so I bought one:
This arrived from China to the UK in only 4 days time and was very well packaged.
Unlike the genuine McWill the screen does not come pre-attached to the screen logic PCB.
Straight away you can notice that this PCB is much thinner, has smaller (and not gold flashed) solder pads and uses smaller SMD (but better rated) voltage regulators.
That said the clone is much better labeled and uses faster rated ram:
Some wire is provided which appears to be solid core 32 or 34 AWG wire. While I did use this as I could thread it easily behind the screen, I think it would be better to use 28 AWG wire instead which I did for the Clock, Sync, Ground and voltage wires as they are the most important.
I almost forgot to connect a wire from T10 to R23!
This small connection is only required for Sega Master System games to display correctly:
Since the screen does not come pre-attached you need to buy some double sided sticky pads with which to affix the screen after everything is installed:
This does make aligning the screen a bit more difficult, but as long as you don’t press the screen down you will be able to gently pry it free to adjust its position.
I then finally attached the two wires required for brightness control to function:
Everything was then re-assembled.
It is rather difficult to show the comparison of brightness settings in photographs but I tried anyway.
Please note that in person the difference is much more pronounced.
Personally I can not tell any difference between this clone screen and a genuine McWill.
Hopefully McWill updates his design to include brightness control in the future.
Awesome post as usual! Somehow I had missed your previous post about the Mega CD. Really great stuff there too. I love the how clearly you format your posts. Very inspiring. Keep up the good work and keep em coming!
Neo Geo MVS 1 Slot (MV1A) Refurbishment:
This is an old repair/refurbishment log from a few years back that I revisited today to sort a couple of things out, which at the time I just didn’t have the correct tools or experience for.
##Please excuse that this log will be presented somewhat out of chronological order to maintain flow!##
Back in early 2017 I purchased a Neo Geo MVS 1 Slot from China for around £30 including shipping.
The listings picture looked like it was in pristine condition and was a 1 slot with a BIOS Socket, however what I ended up receiving was a huge disappointment.
The BIOS was not socketed so a different model was sent, but even worse…
The plastic housing had “CHINA ONLY SALE” gouged deeply into it:
Upon testing it I found that sound was very scratchy (non functional) and games were not able to save any data to the internal memory, but games booted fine.
After taking off the plastic housing to inspect the MVS closer I found out that the capacitors for audio were in very bad shape, leaking electrolytic fluid and heavily corroded:
The Lithium battery was also speckled with rust and had also started to leak:
I also later noticed that the hard DIP switches were not functioning correctly and even had a broken off switch lever on DIP8 which controls CPU Halt:
I contacted the seller who apologized profusely and said if I sent it back she would get a replacement sent out to me (she was just a third party reseller). However, I really didn’t want to deal with sending it back and waiting again for another one.
So I suggested that I would be happy to repair it myself instead if she would give me a small rebate to allow me to purchase the required parts to do so and unexpectedly she agreed as long as I would provide her a receipt for the components purchased:
The first thing I did was recap the MVS.
Neo Geo MV1A Capacitor List:
- 470µF 16v x4
- 220µF 16v x1
- 47µF 16v x1
- 4.7µF 25v x5
However, at this point I only had a manual de-soldering pump, was really in-experienced at de-soldering and struggled removing them especially the ones that were attached to large ground planes.
What was worse is that the capacitor leg at position AC6 was badly corroded and broke off the original capacitor that was installed while trying to remove it. Leading to part of the capacitor leg getting stuck inside the via.
Luckily this was a ground so I was able to scrape a bit of the top of the ground plane on the top of the PCB away and surface mounted the capacitor to the top for its ground leg:
Briefly fast forwarding to today, I now own a de-soldering gun and thought I would revisit this and attempt to get that stuck in the via corroded leg out:
Success! And now that capacitor is correctly installed:
Replacing these capacitors fixed the audio issues.
And now returning to 2017:
I then removed the original VG2430 3v rechargeable battery and replaced it with a suitable VL2330:
Now the MVS could save slot data again and keep time.
Next was removing the DIP Switch which I really struggled to remove but after a lot of time and effort managed to remove it cleanly:
I was unable to find a matching blue DIP switch replacement, but I did find a suitable red one to solder in its place:
I then test the replacement Hard DIPs in the service menu and they all function correctly:
Jumping forward a little bit again…
About 8 months later, I wanted to finally put a Universe BIOS into this MVS but the BIOS as previously mentioned was not socketed:
I had a bit more experience now along with a Hakko soldering station and a cheap Chinese hot air-station, however the removal didn’t go perfect and one trace was damaged on the removal of the BIOS:
Luckily only the top side of the via was damaged so after soldering in a socket i was able to connect Kyna wire to the correct socket pin on the underside of the PCB:
and then thread it through a via to the top side of the PCB where I was able to reconnect the damaged trace directly to the Motorola 68000 CPU:
At the time I did not yet have a Universal Programmer and bought a Universe BIOS v3.3 from Razoola which I then used in this MVS.
Later I contacted him to email me a binary file of the newly released v4.0 BIOS which I burnt and instead placed into my then newly acquired 2 slot MVS and left this running on v3.3.
Jumping forward in time briefly again:
So while I have this MVS out today I decided I would update the 27C1024 EPROM.
First I read the data on it and saved a backup of my original v3.3 Universe BIOS:
Then I erased the data, wrote and verified the new v4.0 Universe BIOS:
Back to 2017:
Lastly I wanted to deal with the housing and for this I filed out the gouged letters and using black epoxy putty I filled them all in. I then used fine grade linishing paper to sand everything down level:
Then I spray painted the result in matt black and left it to dry:
The final results:
Hope this was an interesting read!
If people are interested I’ll also post up my MVS 2 Slot refurbishment eventually.
Awesome post! Be sure to show us the 2-slot refurb!
Thank you for the encouragement to post logs up @Danexmurder
I have to admit your own recent thread gave me a bit of a kick up the backside to write up a few more and to get on with some outstanding projects.
Spent roughly two and a half hours writing up the MVS 1slot refurbishment post.
I waste way too long sorting out images, taking photographs for things that I didn’t already or to replace bad quality ones and then to sort out the jumbled mess of information into some sort of coherent and logical time line that can be followed.
Quite surprised in myself that I’ve somehow made it to 18 written up logs already and I could easily get the number up to 30+ with existing and past projects.
I think I also have a few that are hidden away in the Arcade Collectors Thread and perhaps I should move some of them over to here so they are easier to locate?
Really glad to know there’s more where that came from! My mod posts do take quite a bit of time too. Lately I’ve been trying to limit my picture taking to 3 at each step so there’s less to wade through.
Posts like this are a huge service to the community. Not only are they interesting content to any retro gamer but they’re potential help to other people looking for a guide on the subject at some point down the road.
Really glad that my own posts could be a small catalyst. I think we’re in a positive feedback loop! Keep em coming!
Since the dark cold days of autumn are swiftly approaching, and a second covid lockdown seems right around the corner, it seemed about time to start a desperate hopeless gamegear repair challenge.
I recently obtained it from a junk lot from Japan, and its clear it had been stored for years with batteries inside, upside down. The battery contact themselves are gone. The powerboard, although heavily damaged might be salvageable, although on a first inspection after a round of cleaning reveals a number of soldered pins floating above the pcb.
The main pcb is going to be a real challenge. First round of cleaning with vinegar and alcohol, reveals no obvious major damage expect the pads for on of the buttons having been completely eaten away. A quick first test after cleaning reveals the unit powers on, the backlight circuit is dead, and the lcd shows a flew flickering signs of life. A lot of solder joints look really dull and need to be redone, probably 50% of the board. My only concern is some of the really small through vias that might have been damaged by the corrosion. Next step is removing all caps, known bad components, and slowly start reworking the board.
Shadow of the Tomb Raider Store Display LED mod:
Some of you might have seen this display behind me in some twitch streams and wondered about the story behind it so allow me a moment to go a “little” off topic:
I work in grocery retail and for the release of “Shadow of the Tomb Raider” video game in October 2018 we had a lovely over-sized #TombRaider display setup at the front of our store.
Being a fan of the original game, I really wanted to take this home and I knew after the promotional period the display as per company policy would be destroyed in the cardboard baler.
I also knew the day it was set to be taken off the shop floor and destroyed and I ensured I came into work a little earlier that day to try to save it.
I went up to my department managers and asked if I could take it home but unfortunately they said under no circumstances could I have it and as per policy it was to be destroyed.
Well I really wasn’t happy with this outcome and as I knew I was on very good terms with the store manager who wasn’t going to be in the store for a week or so, I instead got a fellow colleague to help me hide it on the very top shelving in a back corner of the warehouse so as to attempt to try to avoid its disposal.
A week rolled past and no-one else seemed to have noticed what I had done and I got to ask the store manager when he came in and he was happy to grant me permission to take it home:
I however had more plans than to just use it has an ordinary display and I went ahead and bought myself a reel of 5050 SMD 12V Orange LED strip lights:
I also didn’t like the top and piece of the display because on the side it had a huge ugly orange circle advertising my store and the games price and thankfully it could be removed without any damage which also allowed me access to the inside of the display easily from the top:
I then could remove the sun part of the display:
On the reverse of the I applied orange LED strip lights around it to try and simulate a glowing sun effect:
I then threaded the wire through the slits that hold the sun in place and then added a 3.5mm female jack so I could use any generic 12V DC power supply to it:
And the results:
At night, in the dark:
What do you guys think?
Would anyone, like to see another similar project posted up here as well?
I really wish I had gotten a photograph of this display actually in the store.
I thought maybe because it had the whole #TombRaider and an icon of a camera, that maybe some members of the public may have taken photographs with it and posted them online but I just can not seem to find anything.
It is also quite strange knowing that it may be the only one that still exists today…
Looking really great. These sorts of displays are rarely ever seen here anymore here in the netherlands. The last two tomb raider games were some of my favourite action adventure titles this generation.
Finished refurbishing a junk Gameboy pocket with some parts from others that will need new housings, displays, to create at least 1 all original parts console. A very minor blemish on the screen cover bezel top right. Some very minor A/B button wear (haven’t seen a single original one without any). And the back sticker has a few small marks around the edges after 24 years. But I still think it turned out great. Will be up for sale sometime soon. Anyone interested can send me a pm.
The rest of my pockets will be modded with new shells and IPS screens. Can maybe salvage 1 or 2 original displays for a backlight mod with new polarizers if anyone is interested.
CAPCOM CPS2 X-Men vs Street Fighter “B” Repair:
I had the opportunity to buy a few broken arcade PCB at some good prices recently and snapped a couple up. The first one was a Blue (ETC) X-Men vs Street Fighter:
This was listed as not working and wouldn’t display any image but for £45 I thought it was worth the risk.
It arrived promptly the next day and indeed when paired with my A board it did nothing.
So I needed to open it up using a T15 Security Torx bit, but first I had to remove the original CAPCOM tamper seals to get to the screws:
This implies that this CPS2 “B” board has never been opened up before.
I tested the battery with my multi-meter and it was reading at a completely dead 0v.
Thankfully it did not appear to have leaked at all and no trace damage was present.
I de-soldered the battery which was dated April 1993:
Usually I would now replace the battery with a new LS14250 axial lead battery and then reprogram the security key with my CPS2 InfiniKey as I like to keep everything as original as possible, however I did not have anymore left on hand so instead I soldered in the InfiniKey with the correct jumpers soldered.
Since this is a B-4 board you have there is no header to solder to so an alternative mounting point is used and you have to add two wires for Ground and 5v to power the InfiniKey:
A quick test:
That went well!
Also I love this sticker that is on the case:
Awesome! Every time I put an infinikey in a CPS2 I feel like I’m saving an endangered animal. I live knowing that they’ll be able to keep running for years without threat of a suicide. That reminds me. I’ve been meaning to install one in my 1944 board.
CAPCOM CPS1 A+B+C Three Wonders Repair:
The second broken PCB I picked up was a complete CAPCOM CPS1 A+B+C Stack “Three Wonders” that was listed as:
The price was £45 and my thinking was that in the worst case scenario I could at least probably do something with the B game ROM board, but it would be nice if I could get another working A or C board.
This is what I received:
It had a note attached to it stating:
I attempted to power up the A+B+C stack up but got a blank screen which was not unexpected.
So I separated all the boards so I could test them out individually.
CPS1 A motherboard PCB:
I got out my Knights of the Round B board, hooked it up to a known good de-suicided B21 C board and attached it to this 10mhz (non Dash) CPS1 A board:
It boots up with no sound and repeated background elements, but the game appears to play fine and sprites display correctly.
Since I had no sound I decided to use my logic probe on the Z80 CPU which is a common cause of loss of sound on CPS1 games and the Yamaha 2151 to check if pin activity matched what would be expected from their schematics and everything checked out okay.
Next just in case I was mistaken I decided to piggy back a known good Z80 and 2151 I had at hand:
Then I thought I hadn’t even checked the volume pot “VR1” yet. That should have been the first thing!
Straight away I noticed it was a little loose and I could spot a small crack on one of its solder joints underneath so I redid that and now I have audio:
So now I need to look into the Background repeating issues.
Looking at the A board and with a bit of help from the rather confusing schematics that have found their way online, I could isolate the possible issues to a bunch of RAM in the bottom right hand side and to the custom CAPCOM A01 PPU along with a bunch of surface mounted 74LS245.
I’ve highlighted the isolated areas below:
Since the B board covers the top of the A board it is hard to easily probe the components, so I have to resort to turning it over and probed the RAM from the bottom of the board and just reverse the pin outs.
The RAM all appears to be functioning correctly but it is impossible for me to probe the surface mounted A01 PPU and LS245’s. I attempted to power up just the A board without the ROM and security board attached to probe these but since you are missing part of the complete circuit the results won’t be reliable.
I have correct activity on all but 2 of the LS245 which have stuck high outputs, but these are also connected to ram that before had correct pin pulsing that is now also stuck high. So likely there is no issues with them but just for peace of mind I swapped them out with known working ones:
Still no joy.
This sadly leaves me with just the custom CAPCOM A01 PPU being the point of failure and I can’t get a replacement for that outside of taking one from another CPS1 A board.
For good measure I tried using the CPS1 Diagnostics ROM from Jamma Arcade:
But this really just tells me (even though some of the info is missing due to the fault) what I already knew, that the RAM was good as expected.
As a last ditch resort I re-flowed the QFP A01 PPU:
Sadly, nothing improved.
Oh well, this can become a parts board for me.
CPS1 B ROM PCB:
First thing to do here was to confirm if the Program ROM are good and what revision of the game this board is running. I am also little bit concerned if the data is okay on the one EPROM that has an exposed window. The ROM I need to check are 11f (RTE 30A), 12f (not marked) 11h (RTE 35A) & 12h (RTE 36A):
I dump them with my Top3000 programmer and get the following results:
RTE30A CRC: ef5b8b33
RTE31A CRC: 32835e5e
RTE35A CRC: 7d705529
RTE36A CRC: 7637975f
These match the MAME 3wonders.zip which means the data is all good on them and that I have the ETC (World) revision of the game.
Since Three Wonders is one of the CPS1 titles that has a suicide battery, I decide to write four new 27C010 EPROM with the decrypted PROG data from The Dead Battery Society and couple it with my de-suicided B21 C board:
I now try to boot it up using my CPS1 Dash A Board that came with my Street Fighter II Dash Turbo:
We have a fully working game!
CPS1 C Security PCB:
Now I could have stopped here as I had no idea if the B21 on this games C board was working or not.
I could have modified it so it would run “de-suicided” as a generic no Key B21, but I did not want to cut the traces required as instead I wanted to try and keep it original if at all possible.
I removed the battery that was dead (measuring zero volts) from the C board:
Then soldered in a brand new one:
I then decided to order an Arduino Zero and LCD shield so I could attempt to use Arcade Hacker’s CPS1 C board key injector ino script:
I removed my decrypted PROG ROM I had programmed and re-inserted the originals, but covered the exposed window on 12f’s EPROM:
I wired up the C board with Dupont cables originally as per the instructions:
However it just wasn’t working…
After testing everything with my multi-meter in connectivity mode it seems that the dupont cables were making very flaky connections so instead I decided to directly solder wires to my C board and Arduino.
Still no success… I checked online and found that a few people had issues with the C board getting insufficient power during writing so I increased my 5v up to 5.15v and finally it worked:
So I have a working Original C board and B board of “Three Wonders” now!
Spent some time today finishing up these two today. funnyplaying IPS screens, both have a new case with USB-C port so they can be run from an internal lithium battery once you plug in a truepower board from handheld legens/retrosix.
I don’t have anything as impressive to share as Suteneko, but I had a small success recently that made me happy.
I’ve been playing a ton of PSOv2 on Dreamcast lately and all of a sudden the right trigger button on an original controller stopped working. I was all set to use it as an excuse to pick up a new DC Striker controller but paused and decided to take it apart and see what was going on.
After poking around a bit, nothing really jumped out at me, so on a whim I decided to spray the contact points with this stuff:
And that’s when the magic happened. Everything is working great now.
I get a lot of satisfaction keeping old things working and not adding to a landfill, so this ridiculously simple thing really made my day.