JAMMArcade.net – Page 89

WWF Wrestlefest repair log #2

Oct 312016

When switching ON the game, sometimes it had very fast tempo music.

It happened 1 one out of 10 but it was very annoying.

So I used my frequency counter when it happened and I noticed that the 3.58mhz quartz ran at about 10.58mhz!

I changed it with a know good one but again it happened very often.

I was sure it was something connected to the quartz oscillator circuit and given that the resistances are difficult to be faulty I decided to change the cap C47 (33pF) with known good one.

After testing about 30 cycles of switching on and off the game didn’t develop again the problem

Game fixed.

wwf

Liquid Kids repair log #1

PCB Repair Logs, Repair Logs Comments Off

Oct 312016

This game had two problem:

Glitchy and noisy sounds
Blocky background images

liquidk2

Given the high unreliablity of Taito maskroms I immediately tested the ones marked in red which with no surprice some pins not connected internally

liquidk

C49-04 restored the glitchy sound and C49-02 fixed the blocky gfx.

Replacements to be used are 27c400 (4mbit eproms with maskroms pinout)

Game 100% fixed

liquidk3

Toki repair log #1

PCB Repair Logs, Repair Logs Comments Off

Oct 312016

Got this game for a repair which had all screen with washed out colours

toki2

This game has a SEIBU custom named UEC51 which is used as a DAC to output the RGB colours on the monitor.

The input pins were good, but a couple of output pins were fixed, thus creating the images as they had less shades of colours.

I took a good one from another Toki which had other faults and the problem was fixed 100%

toki1

toki3

Diet Go Go repair log

PCB Repair Logs, Repair Logs Comments Off

Oct 312016

The game had two problems.

First one was the music that sometimes when switching on the game was glitched (very fast tempo or corrupted voices)

The first problem was fixed by replacing capacitor C7 which was used to reset the chips and didn’t work correctly.

dietgogo

Second problem was some black pixels on some elements of the background.

dietgogo2

After shorting some data lines of the gfx maskroms I found the one responsibile for the background images.

Normally when a markrom fails you get blocky graphics. In this case was only some bad pixels.

Looking on the solder side of the pcb I immediately noticed one pin of one address line of the background image markrom touching the network resistance beside which forced the address line to 1.

diet3

Disconnecting it solved the problem

diet4

Avenging Spirit Repair log

PCB Repair Logs, Repair Logs Comments Off

Oct 312016

Received this game for a repair.

The game had messed background images

avenging2

Shorting some data pins rams I found the one responsible for the tiles arrangement.

I replaced the one marked in red below and it was infact faulty but it didn’t fix completely the problem.

I noticed that the 74ls745 above it was pressed down badly like if it was hit but something.

I decided to unsolder it and test the continuity of all the pads and infact I found three of them (marked in red) that visually were OK but they had no continuity

with the other chips.

That meant that the internal pad was broken so bad it detached internally

avenging1