Post by donutman on Oct 10, 2024 18:14:04 GMT
If you want to try and figure out what the issue was with this MV1 board, or at least guess, look at the first four pictures before reading further. I ended up buying this board for $30 based on these pics because I thought I could fix the issue.
I already have a MVS-4F in a Big Red Cabinet, which is definitely a jewel of my collection. But I've wanted a MV1 board because the design and all the bells and whistles that come with it. Stereo audio, controller ports, memory card ports, etc. all features that typically are only found on the multi-slot boards. I just have never got one because all the listings for functional MV1 boards seem to be $150 plus 
. Anyways I saw this board with the above pics and jumped on it because the error code shown is a relatively "easy" fix. For those that don't know the Neo Geo systems run a diagnostic on boot up and if something is off it gives a hexadecimal code that points you to the issue. This particular board and the error code pointed to the chips circled here
. Anyways I saw this board with the above pics and jumped on it because the error code shown is a relatively "easy" fix. For those that don't know the Neo Geo systems run a diagnostic on boot up and if something is off it gives a hexadecimal code that points you to the issue. This particular board and the error code pointed to the chips circled here 
These are video RAM chips model Sony cxk5814p-35L. I found a eBay listing for a few of these and bought some to replace the ones on the board. I suspected these initially because in the pictures I could tell that one had already been replaced (because of the non-Sony branding) and they had installed a socket on the board for these chips, which I don't think was done at the factory for these boards.
Anyways I got my chips in the mail pulled the old ones and installed the new ones and... got a new set of error codes
So I was correct that the chip was causing issues, but it wasn't the only problem...
The area circled above are the solder pads for the video RAM on the bottom of the board and they don't look great... I was really hoping that these weren't the issue... but they were. Now I don't have great pictures of what it looked like close up before I started my soldering surgery but here is a picture of things after, specifically the area circled in yellow.
Now this is my guess to what had happened. Someone had previously worked on this board specifically on the video RAM. However, they made 2 errors.
1) They bridged the middle pad with the trace that runs right by it by using to much solder. Before my I removed the extra solder you could not distinguish between the middle pad and the trace. I figured this out mainly by using my multimeter and using the continuity mode to test all the traces. The middle pad was giving be a positive on my multimeter whenever I touched either of the two pads along the trace, so this was definitely a problem.
2) They didn't clean their flux 
(this is just personal pet peeve of mine, but seriously take care of your boards there are only so many left)
(this is just personal pet peeve of mine, but seriously take care of your boards there are only so many left)Now cleaning off extra solder is not "hard", but when working on such small margins with two near touching traces it is extremely patient work. Traces and heat do not mix well together and the last thing I wanted to do was create another issue trying to fix another. I took me about an hour of patient wicking and desoldering but I got the pad and trace to what you see in the picture and the pad no longer gave a positive on the continuity function of the multimeter. So what was the result?
It's alive and working well! I need to solder a battery onto the board to restore the timekeeping and high score saving function and test the other ports on the board still, but it boots and plays games now. I'm pretty excited that I managed to repair this board and that it wasn't scrapped or harvested for parts. Also now I have a spare MVS if my 4-slot dies or if I get another cabinet!
hope you are ok dude
