In the last days I dumped the specific PLD (a PAL16L8) from a X-Multiply PCB (IREM M72 hardware, PAL is on top board ‘M72-C-A’).Chip was kindly provided by my friend ‘robotype’ and dump has been tested as working from ‘cpsystem3’ in a GAL16V8 targeting device.Thanks to both.
As every arcade fan/collector probably knows, Konami makes great things but… sometimes weird.Technically speaking every their board (starting from old ones like Gyruss to latest ones ) has its own hardware layout which involves the use of custom ASICs (Application Specific Integrated Circuit).These ICs are used to semplify the layout and prevent board bootleging.They can have most disparate shape and package and do various functions (sound, graphics, I/O and so on).In particular the Konami ones are really well made but often prone to failure.Some example of their customs :
The one I faced during this double repair log is the one marked ‘054573″ .It’s used on hardware of mid ’90s, it has SIL 15PIN package and it’s essentially a color DAC, it converts digital color signal into an analog one outputting it directly on JAMMA connector (so one IC is used for each RGB colors) :
Here is the IC ‘naked” , picture kindly provided by IronGiant:
It’s a quite fragile part, indeed while I was testing a Gaiapolis PCB, I switch it OFF/ON and I got this (picture on the right) :
Green color was suddenly missing.Once identifying the ‘054573’ DAC responsible of this color I compared with a logic probe its pins to the ones of the other two DACs and they had exactly the same activity except for PIN2 which is , indeed, the output connected to PIN12 solderside of the JAMMA edge.Observed with an analog scope confirmed the output was silent compared to an healthy one of a good DAC:
Replaced it and the green color was restored :
The second PCB, a Metamorphic Force one which also use this kind of DAC, was perfectly working but someone made an awful job on the solderside, “piggybacking” a good ‘054573’ DAC on the faulty one (the green color one also here) and fixing it with hot glue:
Since the eye wants its part, I decided to revert this orrible hack restoring the original status and testing successfully the board :
Konami does great but weird things always, remember! 🙂
16/03/2018
Minor fix.
Text references 8C instead of 19E when sub-cpu EPROM fails checksum.
Fixed output to reference 19E.
04/07/2015
Minor changes.
1.Holding down player 2 start during powerup will enter the diagnostic mode.
2.Some changes made to the presentation of the sprite viewer
30/6/2015
This update includes character and sprite test menu additions to the diagnostic mode. Useful for verifying bad tiles and sprites.
See roms section / downloads for update.
Today I dumped the two specific PALs from an Undercover Cops (IREM M92 hardware).The two devices (PAL16L8) are located on ROM board (M92-E-B) , both dumps have been tested working in a GAL16V8 targeting device.I also succesfully tested the three PALs dumps already on our database (labeled as ‘M92-A-3M’, ‘M92-A-7J’ and ‘M92-A-9-J’ on CPU board), this confirms they should be the same for all M92 games.
Got this pcb from ebay marked with “cracking sound problems”
The game sounded like an old LP with a lot of scratches and missed some sounds.
On this board, the YM2610 handle FM synthesis and PCM samples.
Given the fact that it is very difficult that the sound chip will fail, I started to probe the smd stereo DAC YM3016.
I could hear the same cracked sound coming out and I was sure that changing it would fix the issues.
I found a donor board and soldered a new DAC.
Retested the pcb and same problems.
At this time I was quite sure that the sound chip itself was broken.
Suddendly I remembered the most obvious thing to test first: the sound rom C43-01!
It was a maskrom….marked Taito….they had the most unreliable supplier ever.
In the past, I found many Taito maskroms which caused gfx faults because of internal faults.
After cheking the maskrom on my eprom programmer one pin was not making contact and it was clear that is was an internal break.
Burning a 4mbit eprom with maskrom pinout (like a 27c4100) restored the sound.
