Depth buffer memory. Cpu Board. Scroll memory

Depth buffer memory

This reports as IC61, IC62:

Now this one is a little odd, as there is an IC62 but no IC61. Even on a step 1. 5 board there doesn’t seem to be an IC61 (unless it’s on the bottom? ). Anyway I haven’t yet replaced this IC so will update with results of replacing IC62.

The choice of IC in this case is interesting as the depth buffer uses the same Mitsubishi M5M410092BFP as the video frame buffer, but it doesn’t use the video function.

Anyway here’s what it looks like when this IC isn’t working properly:

Sorry about the bad photo, but notice the horizontal lines that occur on only some of the textures

Cpu Board

The only two errors I’ve encountered with CPU Boards are RTC problems and scroll memory.

The RTC problems report as low battery although i’ve seen another RTC error that is different. Changing the battery in my case didn't fix these issues. As it doesn’t prevent or really affect gameplay I haven’t concentrated on these issues.

Scroll memory

This error reports as IC17 and IC18 (sorry no photo)

These IC numbers are accurate and its simply a case of replacing these ICs on the cpu board.

The range of problems that faults in these ICs can cause is quite varied and includes a number of malloc errors on boot. I’ve also seen (in Sega Rally 2) a fault in the scroll ram can cause a couple of the roms to report as bad when the same rom board on another cpu board reports them as fine. In my case the fault cased the game to run for a few minutes then crash and it would have malloc errors on reboot. Changing these ICs fixed these problems.

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