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Cadash repair log #2

Jan 242018

Received from Spain this Cadash PCB (it turned out to be an undumped Spanish version)

Board was stuck on a garbage screen :

A clicking sound suggested that the watchdog circuit was active, infact both /HALT and /RESET lines of 68000 main CPU were going LOW and HIGH in an endless loop.At first glance I thouhgt the Taito custom ‘TC00220IOC’ (responsible of generating the master reset for whole system) was faulty since this is a very prone to failure part :

But I was wrong since I replaced it with no changes.Probing the 68000 CPU I found that data line D0 (pin 5) was stuck low, using a multimeter revealed it was shorted to ground:

Looking at solderside I traced the pin back also to pin 25 of a Fujitsu MB8422 Dual-Port SRAM (part of linking mode circuit)

I cut the trace and the short was cleared (so the I/O pin of the MB8422 was internally shorted).Finally board booted into game:

But I noticed two problems : the buttons of the Player 1 were not responding and sound had rustles, you can hear it from this video :

As for first issue, using a logic probe revealed the relevant pins of JAMMA edge connector were stuck LOW :

Inputs of an arcade board must be HIGH when not activated, they are usually pulled in this state by resistors.Indeed, tracing back the pins of the three P1 buttons from JAMMA connector lead me to some custom resistor network:

The array @RRC1 was the one involved so I removed and replaced it, this fixed the controls issue.As for sound, using an audio probe I figured out that the bad audio was coming out from the TL074 OP-AMP from Texas Instruments (which are really prone to failure, have replaced tons of them)

Replacing it restored a crisp sound.End of job

Kuri Kinton repair log

PCB Repair Logs Comments Off

Jan 202018

Received from Austria this faulty Kuri Kinton PCB, an obscure fighting game manufactured by Taito in 1988 :

Board is very compact, hardware platform is called ” Taito L system” based on the the ‘TC0090LVC’ (a custom Z80), an all-in-one CPU/system controller which does everything (game logic, tile handling, sprite handling, I/O handling, etc).At power up I was greeted by this scenario:

The game played almost blind, you could coin up but graphics were all scrambled.Ruled out the two GFX 4Mbit MASK ROMs, very few was left to probe.There are four 62256 SRAMs (32K x 8-bit) whose data/address busses are tied to the ‘TC0090LVC’ :

Probing them revealed unhealthy signals on data lines of some of them:

I decided to remove them all :

Actually only the ones @IC9 and IC10 failed the out-of-circuit testing:

Replacing them fixed board completely.End of job.

Konami ‘054986A’ and ‘054544’ reproduction

Reproductions 10 Responses »

Jan 162018

Raise your hand those of you, arcade enthusiasts/colectors, who have never dealt with the Konami ‘054986A’ and ‘054544’ audio modules?I think none…

This little project needs no introduction and technical explanation, we have treated this topic many times during our repairs.I simply reproduced (be careful, not reverse-engineered!So my repro still need ICs of original, especially the ‘054321’ ASIC) my way both modules with same results of original parts.I hope this will be useful for preservation purposes of our PCBs.

Xexex repair log #1

PCB Repair Logs Comments Off

Jan 162018

Received from Austria this pretty mint Xexex PCB:

According to the owner the board had only faint sound but actually it was not booting for me resetting on attract mode:

At a closer inspection I found some lifted pins of the custom ‘053250’ which I promptly reflowed :

Finally the board successfully booted but, as expected, with very low sound , you could barely hear it with volume set at maximum level though:

Obviously the culprit was the ‘054544’ hybrid audio module:

I removed it and changed all the electrolytic capacitors (repainting it as well)

This restored full sound.Then I thought this was the right chance to try out my reproduction:

Testing was successful :

Kaneko ‘MC-1091/MC-8282’ reproduction

Reproductions Comments Off

Jan 082018

This is another little reproduction project that arose during my repairs.

Some time ago I came across an Heavy Unit PCB which played fine except for the inputs that were not working.This had an explanation:

This SIL custom (in ZIP46 package) marked ‘MC-8282’ was broken in half.Like the silkscreening tells (I/O), this custom handles all the inputs.I looked into my spares and found some Kaneko boards that used a similar custom with same number of pins but marked ‘MC-1091’ instead :

I tried it in my board and all inputs were working again so I came to the conclusion that the ‘MC-8282’ and the ‘MC-1091’ are essentially the same.Not happy enough, I decided to try to reproduce it.As always in this case, I first ‘stripped off’ the component by removing its coating and did some hi-res scans:

As you can see from above picture, the designers pratically embedded in a single component a typical inputs circuit that can be found on many arcade boards.Techinically we can think of this custom like a big multiplexer made of four 74SL253 TTLs which receive on their inputs the signals from JAMMA edge connector.Obviously there is a common output enable signal and two selection ones as well.All other parts are printed film resistors (the black squares, the tiny ones are for pull-up), ceramic capacitors (for by-pass and signal filtering) and a couple of SOT-23 parts (involved in P1 and P2 coin input) which I was able to identify as dual diodes common cathode :

I fired up my multimeter in continuity check and in some time figured out the design so I made some rough prototyping on a breadboard:

I had success so I start to draw schematics.I intentionally omitted some not vital parts (like the many ceramic capacitors) and used SMD resistors arrays, this allowed me to save room on PCB layout and keep the same dimensions as the original part.I sent the design to manufacturer and received the bare PCBs after some weeks:

I assembled a unit:

and installed it on PCB:

Testing was successful, all the inputs of both players (plus SERVICE ) were correctly mapped and working:

For reference the MC-1091/MC-8282 custom can be found on these Kaneko/Taito/Toaplan PCBs (list can’t be incomplete so other additions are welcome)

The Berlin Wall
Magical Crystals
Bakuretsu Breaker
Blaze On
Shogun Warriors
B.Rap Boys
Great 1000 Miles Rally
Bonk’s Adventure
Blood Warrior
Jackie Chan
DJ Boy
Gals Panic 1, 2, 3
Air Buster
Snow Bros
Heavy Unit

See you all to my next reproduction project!

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