Just a quick (but quite important) fix.Got from my friend Josef this spare Capcom C-BOARD with CPS-B-01 ASIC on it:
Whatever game I tried with it, I got sprites issues.Strider for example:
I was pretty sure the CPS-B-01 ASIC was bad, it’s very prone to failure IC but I decided to have a look at it.Doing a continuity test with my multimeter on solderside of the C-BOARD I found two broken traces:
I promptly patched them with some AWG30 wire:
This restored correct sprites:
Today, after repairing it, I dumped the PALs from a Sega Mega Play PCB.There were six devices, I was able to reverse three of them, one was already dumped by Porchy from a Mega Tech PCB.The remaining two use latches so a deeper analysis is required.
My friend Joachim sent me this Mega Play system for a repair:
The Mega Play is the name of a JAMMA-based arcade boardwith the ability to run Sega Mega Drive games. It was the second attempt by Sega to bring the home console to the arcades, following the Mega-Tech arcade system.Games come in form of cartridges:
At power up the system booted but got stuck on the welcoming screen not loading cart in whatever slot was inserted:
As I said, this system operates on the same core components that the Sega Genesis uses (plus some additional hardware, such as an additional Z80 and Master System VDP for driving an optional second monitor that displays a list of games installed).In particular there are two VDP (Video Display Processor) custom chips marked ‘315-5433’ and ‘315-5313’.When I went to inspect them, I found some lifted pins on the latter :
In particular lifted pins were some from 55 to 70 which are directly connected to the 68000 main CPU data bus :
I reflowed these pin and this was enough to fix the board:
Today we have an important Sega PLD update.After verifying the Out Run dumps we had (having confim they match the ones from my board) I was able to reverse and successfully tested into GAL18V10 devices two of them (original chips were one CK2605 and one PLS153).
Always in Sega, I dumped and successfully tested into GAL devices four PLDs (three CK2605 and one PLS153) from an original Fantasy Zone PCB on System16A hardware.
My friend Alexander sent me this original Sega Out Run PCB for a repair:
After adapting it to JAMMA I powered it up and I could noticed the defect :
There were some dots on the screen in which I could recognize parts of sprites (lile a ghost images, I’d say).Since video board is the lower one, I could not reach with my logic probe or scope the involved circuitry made of the 315-5211 custom Sprite Generator plus sixteen 62256 SRAMs chips :
RAM test was successfully performed but didn’t cover all the chips :
So I went to piggyback each RAM chip and when i did it for the one @IC71, the issue was cleared:
Time to remove the chip and install socket:
Obviously the desoldered chip didn’t pass the test on my programmer:
End of job.