Mitsubishi 'MN50005XTA' and 'M60002-0118P' reproduction

The Mitsubishi 'MN50005XTA' and 'M60002-0118P' are two custom chips found on Tecmo arcade PCBs of mid/late '80 like Rygar/Argos no Senshi, Silk Worm, Gemini Wing, Solomon's Key and few other boards.

The Mitsubishi 'MN50005XTA' is a DIP28 .600mil plastic part :

Whereas the 'M60002-0118P' is DIP42 .600mil (always with plastic case)

I had these two custom ICs in my reproduction TO-DO list since some time, it was only matter to find some bootleg boards to study how the function of these custom ICs were reverse-engineered.

As soon as I found them I extracted the equivalent circuit and then designed the replacements with simple TTL gates :

'MN50005XTA' reproduction :

'M60002-0118P' reproduction :

Both replacements worked at first try when tested on my boards (Rygar and Silk Worm)

 

 

 

 

 

 

 

Since the designs have been validated a CPLD version of the TTL reproductions will follow later.

Altered Beast repair log

Got for repair an original Altered Beast PCB (on Sega System 16B hardware)

Board was in decent condition :

 It was marked with 'GFX issue" and, indeed, at first power up I could see it :

There were missing horizontal lines all over the screen.The fault(s) was located on motherboard since the ROM board was successfully tested with a known good motherboard.

At first glance this issue appeared to be related to backgrounds graphics, indeed someone previously replaced in vain the '315-5197' PGA custom tiles generator and a couple of RAMs connected to it.

I ran a memory test which reported all RAMs as good.But on motherboard there are other memory chips not addressed by main CPU therefore these are not covered by the test, in particular these RAMs are tied to the '315-5196' PGA custom sprites generator.Here is a RAMs chart for reference :

The sprite RAMs ICs were all Sony CXK5814 (2K x 8-bit), I know from my experience that these are quite prone to failure.I started to probe the two @G2 and G3, the signals on most of data pins looked like unhealthy compared to a good one (on the right of picture below)

I pulled both chips :

Actually only the one @G2 failed the out-of-circuit test (the other was good)

I installed a good RAM chip on socket :

This fixed the issue and board completely.Another successful repair.

Irem 'KNA65005-17' reproduction

Another Irem custom IC has been defeated and successfully reproduced.

After the 'KNA70H015(11)' and 'KNA70H016(12)'  

Irem 'KNA70H015(11)' and 'KNA70H016(12)' reproduction

I took into account the 'KNA65005-17', a DIP48 part found on M72 and later hardware like M81, M82, M84 and M85 (although with scratched-off part name)

The functions of this custom IC were reversed by analyzing and comparing the signals between original and bootleg hardware.As always I ended up with a prototype made with TTLs gates:

After some tweaking, it worked fine on all PCBs I could try.

Here's testing on R-Type (M72 hardware) and Dragon Breed (M82 conversion) 

 

Since the design has been validated a CPLD version of this TTL reproduction will follow later.And a full re-engineering of the entire Irem PCB is more possible now.