Mar 192017
 

Got this X-Men PCB for a repair :

As often happens on Konami boards that use hybrid audio module (the ‘054544’ in this case) audio was horribly scratchy and loud:

Electrolytic capacitors  had already been replaced with same type but this obviously was not enough:

So, I removed the module from PCB and decided to fully service it:

I replaced with new parts the 4558 OP-AMP (I used a compatible LM358) and the AD1868 DAC as well:

At same time I reinforced some poor connections  :

Lastly, as icing on the cake, I varnished with black laquer :

As always I do, I installed on PCB a couple of 1.778mm female round machine-tooled strips.This was the final result:

Time to test :

Job done.

P.S.

For the uninitiated, the ‘054544’ module has been reproduced, you can read more about on these threads:

https://forums.arcade-museum.com/showthread.php?t=386416

https://forums.arcade-museum.com/showthread.php?t=396393

 Posted by at 2:46 pm
Mar 182017
 

Some months ago I received for a repair this Tatsujin Oh PCB (known outside Japan as Truxton II)

As you can see from the above picture, the custom ‘HK-1000’ (used for inputs) in front of JAMMA edge was missing but this was not the main problem, board won’t sync up:

All the graphics and video timing signal (HSYNC, VSYNC, etc..) are generated by a large surface mounted ASIC (208 pins QFP package) marked ‘GP9001’:

You can find its pinout on page 32 of the Knuckle Bash schematics:

http://www.jammarcade.net/files/Schematics/Arcade/Knuckle%20Bash.pdf

The IC was previously reworked by someone in a bad way, many pins were bridged together, flux residuals were not cleaned.So I decided to remove it :

and solder it again:

Happy with the result I powered up the board again and I was greeted but this static garbage screen:

Probing the main 68000 CPU revealed no activity on data bus.Doing a visual inspection of PCB I found a couple of severed traces on solderside just around the CPU area:

Patching them allowed the board to boot but, obviously, due the lack of the ‘HK-1000’, the game was stuck on a ‘TILT’ error message:

Input check in TEST mode reported ON most of them  :

Now some words on the ‘HK-1000’.As said, this custom handles all inputs and it’s has been adopted in later Toaplan PCBs.There are two revision of it, the early one has a ceramic package and due this nature it’s very prone to damage and failure.This revision is used on Truxton II/Tatsujin Oh and FixEight:

The newer revision is more robust and it’s used on Ghox, Pipi & Bibis:

Back to repair, from available info it seems the functions of this custom can be reproduced using a couple of 74LS240  (actually the custom handles also the coin counters and lockout but we can omit it), this is not a suprise for me since a lot of previous Toaplan boards use same design with these TTLs (see for example Truxton, Wardner, Hellfire and other).Doing some tests with a single 74LS240 I was able to successfully map some inputs turning off the TILT error

This allowed me to enter in game :

Later, owner of the board installed the missing HK-1000 and confirmed the board was perfectly working after my repair:

P.S.

I’m currently drawing schematics for the replacement of the HK-1000 and I will post here my results.Stay tuned.

 Posted by at 11:12 pm
Mar 182017
 

Some days ago I had this Truxton PCB on the bench:

Game had wrong colors on some background/foreground objects, like title screen

This part of graphics is generated by a ceramic PGA custom marked ‘NEC D65081R’ which addresses four 1Mbit MASK ROM and read/write data from/to four 62256 static RAMs:

Address bus is daisy-chained between the custom, the four MASK ROMs and the four RAMs, all was in order here.Custom receives data from MASK ROMs and transmits/receives to/from from RAMs on two different bus.When I went to check connections, I found no continuity between pin 17 (D5) of the RAM @18F and the custom.Here is where trace from pin of the RAM goes under the custom (picture taken with a USB microscope)

Infact, if I pressed the custom in this corner, the fault went away.I simply reflowed this dry joint and all came back to normality.

 Posted by at 6:44 pm
Mar 162017
 

I bought this game for my collection declared perfectly working.

Flashgal runs on the very same pcb of other two games developed by Kyugo which are 99 Last War and Legend.

On the bottom pcb it is silkscreened CVG-48C which is very similar to the codes used by ORCA on their hardware

 

Anyway  it seems that in these days I am very unlucky because the game once fired up had a sync problem

 

Tracing back from the SYNC pin I came to a 74LS08@2P

With the frequency counter I got very unstable readings so I proceeded to piggyback it with a good 74LS08 which restored the sync.

After changing it, it tested good out of circuit, yet with the new TTL in place I got a stable sync….

The screen looked very reddish so there was obiviously a palette problem

I checked the palette rams and they were all good so I dumped the colour proms until I found the RED component one @1J which didn’t match anything in MAME.

The prom is an 82s129 and it is almost impossible to find an empty replacement these days.

Therefore I went again for the Bprom to Gal replacement already used last year in another repair log:

Mad Gear repair log AKA reproduction of a bprom to GAL

Since the prom was the very same type I replaced for Mad Gear, I converted the prom file to the PLD equations using Elgen tool U2pa and I reused the same pin configurations which fits nicely without any major hardware mod except a jumper wire to connect GND to the correct pin on the GAL

I tested the the game but I noticed something strange:

The colours were right but there were glitches on the left and right borders and also a flickering red component across all the screen (which cannot be seen on the static image offcourse)

At first I thought it was an access time problem with my GAL , therefore I burned the fastest one I had  but no luck.

I tested directly the signals of the PROMS and  found out that the CE pins were not tight to GND but were controlled by another ttl.

Soon it became clear why it didn’t work: the GAL was sending datas out of sync  therefore producing artifacts.

Since I am not a programmer I asked to Elgen and Caius (who asked to Porchy) an advice how to replicate on the PLD  a tristate behaviour.

All of them were very kind and in few minutes they informed me how tristate works on PLD equations

I added the needed modifications to my PLD equations by declaring each data pin  enabled when pins CE1 and CE2 were low.

 

This completely fixed the colours on the pcb with no artifacts:

 

Again a big thanks to Elgen from http://elgensrepairs.blogspot.it/ for the invaluable tool  and to Caius and Porchy for being always very helful

 

Mar 162017
 

I bought this game declared 100% working for my collection but as soon as I fired it up I noticed something strange:

 

One of the mountain layer looked very strange and there was also some stripes of mountains in the sky

This game has no schematics and it is a particular complex and populated hardware with lots of TTLS and rams.

The game is on a 3 layers pcb so I had to find a way to test the components in a confortable way:

 

The upper board with the connector has the cpu and sound section, therefore I started to test the bottom pcbs and by shorting some signals I finally found the circuit dedicated to the last parallax layer which is near eproms 19 and 20.

All the signals looked good but the 2114 srams has some dead signals coming to 4 addresses.

Tracing back I found a Texas instruments TTL  74ls157@9C   whose outputs were all totally dead

Changing it fixed completely the background layer: