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.