Game booted and could be played but all the screen was full of garbage and flashing.
I found one of the two rams circled in red that was really hot. Data signals were weak so I decided the replace it.
I could now see some parts of the background, so I decided to replace also the other ram and the game this time was fully restored.
After receiving news that Eduardo Cruz had updated the code of the Kabuki Desuicider to support also the final games with eeproms that in the past didn’t work (Super Pang and Poker Ladies), I took my Poker Ladies board to desuicide it.
After reprogramming the Kabuki chip
I fired up the game but I was welcomed with a bad surprise:
I had corrupted graphic on some sprites ( title sprite and back side of the cards).
Luckily after locating the 2 chips responsible for the sprites, one of them ( @2J )had internal damage (programmer warned about missing contact on a data line)
The chip was a 1mbit maskrom but 32pin, that means I could do a 1 to 1 change with a programmed 27c1000 or equivalent without any flying wires.
Problem was 100% fixed
After 6-7 years years I decided to dig up my Centipede board (already repaired several times in the beginning) to make a play and I noticed that it was too quite.
Some sounds were present but something was missing…
After firing up Mame I immediately noticed that the sound missing was the centpede one!
After a brief looking at the schematic I understood that the Pokey chip was somewhat faulty.
Started the tone test and the channel 4 was silent.
Luckily I had a Missile Command lying around which was in very bad conditions but the Pokey was good!
So sound fully restored changing the Pokey chip @C3
Here is a recently repaired Quartet running on Sega pre-system 16 hardware.
The 3 replaced chips are highlighted in red. I will explain every step of the repair process below.
1) The game was booting to a garbled screen:
The 74LS04 located at 1H (an inverter, manufactured by Fujitsu) had good clock signals on entry pins 11 and 13 but had floating signals on outputs pins 10 and 12. Replacing the chip changed the result on boot…
2) I then got a screen with garbled graphics but with a countdown appearing at the center.
This is normal on pre-system 16 games. Normally, after reaching 0, the game is booting. Here, I got a black screen after the countdown.
I noticed that the reset pin on the 68000 had a square looking wave signal, which was pretty weird (it should be a linear signal at +5V). The chip that generates the reset signal is a MB3771 located at 1G (again, manufactured by Fujitsu). Probing its pins made the game sometimes booting. I replaced it by a new 3771 chip and the game was now starting normally.
3) The game was working and playing fine except for the FM sound that was inoperative (only the voices could be hear). It was due to the YM3012 located at 1B (a DAC). It had good looking signals on its inputs but nothing seemed to get out of its outputs. After replacing it I got the FM sound back.
Now the game is fully working.
Another Rainbow Islands PCB to repair.
This one had issues with the sprites which were broken up and seemed to be repeating, looked very much like a stuck bit on the sprite addressing;
All tiles and background graphics were fine, so I knew it was something to do with the sprite circuit.
The first thing I did was to look at the area where the sprite data is read from the two eproms. The two 74LS244 buffers checked out fine, but one of the 74LS373 Octal Latches had an output pin stuck HI (pin 9);
So I desoldered it;
I confirmed the Octal Latch was bad in an IC Tester. So I soldered in a socket and replaced with a fresh Octal Latch;
PCB sprites now restored;
