Aug 112019

Another custom IC successfully reproduced, it’s the Irem ‘KNA6032701’ , a 42 pin DIP 600mil IC used on M62 (Kung-Fu Master, Lode Runner, Spelunker and other), M75 (Vigilante) and M72 (on some  type of ‘M72-B-D board) hardwares

As usual I reproduced it my way by observing how it was reverse-engineered on bootleg boards obtaining in a board layout with same dimensions of original part :

Testing on a Kung-Fu Master PCB :

 Posted by at 10:26 am
Jul 262019

This is another ‘poor man’s’ custom IC reproduction I made with no use of CPLD or other complex programmable logics.The part reproduced is the Konami ‘083’, a 28 pin 600 mil in DIP package which most of times comes with scratched-off part name :

It can be found on several Konami PCBs, you can refer to this useful spreadsheet (credits to ‘mattosborn’ on KLOV forums)

As always I observed how its functions were reverse-engineered on bootleg boards and made my own reproduction with simple TTL gates logics :

Final successful testing on a Mega Zone PCB:


 Posted by at 11:05 am
Jul 262019

The ‘CUS99′ (simply silkscreened ’99’) is a custom IC used on Namco arcade PCBs.It’s a 16 pin SIL component covered with a brownish coating :

It can be found on pre-System86 (Pac-land, Sky Kid, Gaplus, Dragon Buster and other boards..), System86 (Rolling Thunder and other games on same PCB layout) and System 1 hardware.From the scarce info about it the ‘CUS99’ is involved in sound volume control but we knew nothing more detailed about, pinout from official schematics apart :

Recently I’ve been sent by the user ‘JorgePT’ a pile of System 1 boards for repair hence, with his permission, I analyzed the part. After drawing schematics of its internal structure I came to the conclusion that the ‘CUS99’ is nothing more than a 4-bit DAC with output level control performed by analog switches.Its design was quite simple and easy to reproduce with few parts  :

Testing of the repro on a Pac-Land PCB was successful:

Thanks again to ‘JorgePT’ for his willingness.

 Posted by at 10:32 am
Jul 262019

Here’s a repro of the KNA 6032601 found on boards like Kung Fu Master and Tropical Angel.

While it’s not known to fail as often as the KNA 6034201 (which Caius has already made a repro of ) it has been know to start failing lately.


It’s a 40 pin custom IC on the TOP board of the kung Fu Master stack, sitting at E1 & E2 between two rams and the colour proms

This most likely deals one deals with the final image processing, like layer priorities, just before outputting data into the colour proms

I used a bootleg to see how this one was reverse engineered by bootlegers at the time and identified and area between the rams and the colour proms.

Tracing multimeter confirmed those 9 LSxx ICs were indeed connected to the same ICS as the custom. So I fired up easyEDA and got busy .

A few days later, voila! a working IC and a working board. Not a complicated thing to do, it just takes time to trace back everything .

Huge thanks to Caius for his recent inspiring work on making repros for a lot of these custom ICs and has prompted me to look into the topic and start making my own too. The more the better !

And as usual, for those who prefer the video format :

Namco System 1 ROM boards repair log and ‘CUS95’ reproduction

 PCB Repair Logs, Reproductions  Comments Off on Namco System 1 ROM boards repair log and ‘CUS95’ reproduction
Jun 072019

Recently I received a pile of faulty Namco System 1 hardware.I’ve been sent boards grouped by type because, as you may know, it’s a complex system made of a smaller CPU board and a bigger ROM board.I started to troubleshoot the latter.Three of them were tagged as “working but with sound issue” when tested with the same Pac-Mania ROM set :

The issues went from corrupted sound to lack of some music tracks :

Using an audio probe I figured out the sound was properly coming out the YM3012 DAC but then got corrupted before being amplified.In the middle there are two TL084 quad OP-AMPs :

This part is well known to be very prone to failure especially the ones made by Texas Instruments manufacturer like in this case so I removed them all and they failed the out-of-circuit testing :

Replacing them with good ones restored full sound but while I was testing the boards I noticed some inputs were not working on one.A quick visual inspection revealed this :

The custom resistors/capacitors array marked ‘CUS95’ was cracked in half.Not having a spare I decided to analyze the part and reproduce it :

Three boards were fully functional now.The last one had also other issues besides sound not properly working as most of graphics were missing replaced by garbage,  sprites were barely visible :

The tilemap generation is handled by the custom ASIC ‘CUS123’ (plus the ‘CUS133’ on CPU board) which generates the addresses to the character ROMs:

It was most likely faulty so I replaced it :

This restored the graphics and left me with the sound issue to fix, music were completely missing on this board:

Replacing the two TL084 OP-AMPs didn’t do the trick this time so I went to probe the rest of circuit.I found that the 78L06 voltage regulator that provides +6 Volt to the YM3012 was outputting only +2.7 Volt :

Replacing it restored full sound.Namco System 1 multiple repair accomplished.


 Posted by at 11:27 pm