Poker Ladies repair log #2

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Mar 062016
 

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

Foto 05-03-16 12 31 01

I fired up the game but I was welcomed with a bad surprise:

Foto 05-03-16 11 22 27

 

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.

Foto 05-03-16 13 07 54

Problem was 100% fixed

Foto 05-03-16 13 08 25

 

Centipede repair log

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Mar 062016
 

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

centipede

Quartet repair log

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Mar 042016
 

Here is a recently repaired Quartet running on Sega pre-system 16 hardware.

quartet1

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:

quartet2

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.

quartet3

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.

quartet4

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.

Rainbow Islands repair log #10

 PCB Repair Logs  2 Responses »
Feb 252016
 

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;

IMG_20160224_112137583

IMG_20160224_112142174

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);

IMG_20160224_112155598_HDR

So I desoldered it;

IMG_20160224_113645345

I confirmed the Octal Latch was bad in an IC Tester.  So I soldered in a socket and replaced with a fresh Octal Latch;

IMG_20160224_114050662

PCB sprites now restored;

ri_pcb_2

ri_pcb_3

Atari Asteroids Deluxe repair log

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Feb 202016
 

Sometimes lightning does strike twice.

I was recently sent an Asteroids Deluxe PCB which was exhibiting corrupted vectors.

When I got the PCB, I put it on my test rig and was presented with the following in TEST mode;

IMG_20160215_160220667

GAME mode;

IMG_20160215_160158687

The symptoms were pretty much identical to the last Asteroids repair log I posted.  Note however this is an Asteroids Deluxe, however it is pretty much identical hardware to Asteroids except that Asteroids Deluxe has a pure digital sound circuit via a Pokey chip (Asteroids is analogue and no Pokey).

I immediately probed the 74LS42 decoder at E6, which had two outputs stuck HI.

IMG_20160215_160124793

So I desoldered it;

IMG_20160215_161027015

Tested it in my IC tester;

IMG_20160215_181037047

Socketed and replaced it with a fresh decoder;

IMG_20160215_161344449

Fire her up again;

IMG_20160215_160348150

Now working, except that the PCB would sometimes crash or refuse to boot.  I was able to determine that three of the six ROM sockets were worn.  So I replaced all of them for reliability;

IMG_20160215_162641553

IMG_20160215_165025775

IMG_20160215_162807350

Now working 100%.

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