Caius

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
 

I dumped the only PAL from a Gunbird 2 PCB.Original device was a secured PALCE16V8H marked ‘PS5-1’ @U18.Dump has been successfully tested onto a GAL16V8 targeting device.

 Posted by at 6:54 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
 

Today I dumped two PALs from a Big Fight and Ninja Emaki PCBs.In the first board, device was a secured PEEL18Cv8 located on daughterboard @IC56, I was able to fit equations in a GAL18V10 targeting device.In the latter board, device was a secured PAL14H4 @10F on CPU board which I successfully reversed onto a GAL16V8.Both boards had also other PLD devices but all set as registered so not dumpable.

 Posted by at 6:07 pm