I had this rare Irem Ken-Go PCB (an undumped version included in latest MAME release) from my friend Joachim for a repair:

The board played fine except for an issue where all sprites were formed but missing all colors appearing like black shape:

Sprites generation circuit is located on top board where some customs lie:

Documentation for this specific game was not available but luckily I could know function of the various customs by looking at the R-Type schematics and so identity the one involved in the sprites palette generation:

The custom itself was marked ‘KNA91H014’ in 60 pins QFP package:

Probing it revelead that inputs were fine but outputs had irregular signals:

So I opted for replacing this custom (taking a good one from a dead Vigilante board)  :

This was the right move since sprites were correcly restored:

End of job.

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:

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: