Neo Geo MVS 2 Slot (MV-2F) Graphic Corruption Repair:
Recently while I was testing my new JAMMA setup I found that I was unable to get this 2 Slot MVS to sync with my arcade monitor:
I discovered that the delicate trace for the Video Sync had broke at some point in storage:
So I had to run a small bodge wire to fix the issue:
But then… Suddenly I started getting graphical issues urgh:
I replaced the Uni-Bios with a freshly created Neo Diagnostics BIOS to help diagnose the system:
It appears I am getting the error message: VRAM ADDRESS (A8-A10/A8-A14)
So it looks like the VIDEO RAM as gone bad and from the low address that failed it looks like it was the slow ram which is a pair of SONY CXK58256MM-12 RAM:
While I did locate some identical NOS RAM in China which I ordered, I didn’t want to wait and thus looked to see if I could find a local UK seller with stock of a 5volt 256kbit SRAM JEDEC pin compatible, 32K x 8bit, 120ns or faster RAM in a 28 pin SOIC package that I could use and found some NEC UPD43256BGU-70LL RAM that I could use and got it delivered the next day:
I use a hot air station and plenty of flux to remove the original video ram:
Then drag soldered in the replacements:
Success all Diagnostic tests now pass:
I then removed the Neo Diagnostics BIOS and re-inserted the Uni-Bios.
Everything is now back to working as intended:
