18 Apr 2018

MV1-F - SNK (repair log)

This one took me hours to fix...
When I got it it was working fine except newer games had sound corrupted (wrong or missing samples). However it didn't throw any sound related error (Z80 error) so I started to probe the sound RAM (6116 type), CPU (Z80), sound chip (YM2610) and sound ROM (M1 mask ROM) but didn't find anything weird. I also checked every single trace connecting the various chips in the sound section but they all turned out to be fine. This is where things got messy...

Problem being noticeable only with newer games I thought it could be related to higher address lines.
I pulled the audio RAM thinking the high part of its range was faulty, installed a socket and fitted a new chip: nothing changed.
Next probable culprit was the sound CPU as it's overclocked when running on a MVS motherboard (same mistake Capcom did with CPS1 motherboards). Same treatment, socket, new chip: no difference.
Ok, ok, could it be a partially corrupted M1 ROM? No it wasn't.
Humm and what about the sound chip (YM2610)? It has a shitty pin space (SDIP, 0.07" pitch instead of 0.1"), I had most difficulties finding an appropriate socket for a decent price. But nope, it wasn't faulty.
Last one in line was the custom NEO-D0 chip (SMD). I pulled one from a known working board and this is where I discovered a bad trace underneath it! It's the /NMI signal coming out of pin 29 of the custom chip. How could I have missed it!?


Anyway, I soldered the known good chip in place and patched the broken trace.
Board was fixed...


Out of curiosity I soldered the potentially faulty custom chip on the good donor and it worked just fine.
Conclusion: I've replaced all the chips in the sound section because of a single broken trace (ok, mostly because I missed it somehow).

11 Apr 2018

Conversions on Namco NB1 hardware (Nebulas Ray)

An other job I've done after being poked by different persons.

Nebulas Ray uses a custom chip used for security (named keycus) preventing the game from booting if absent. I simply patched the program ROMs to get rid of it.

Only difference I've found so far is some stars in the background are supposed to be displayed randomly according to values coming from the keycus:



In the patched version they are aligned (no RNG):


Of course this could be circumvented by adding a subroutine generating "random" numbers using whatever fluctuating value I can find in RAM as seed for instance.


[EDIT]
Now stars fixed!

Here are the ips files for the world version of the game:


4 Apr 2018

Conversion SF2' to Warriors Of Fate (CPS1 no Q-sound)




I continue my conversion job with an other Q-sound game I've modified for non Q-sound hardware: Warriors of Fate.
Samples are from the bootleg named Sangokushi II: San Jian Sheng.

1) Material needed

1.1) If you use a 91634B-2 B-board (EPROM)
 - 10 * 27C4096 ROM (8 for the graphics and 2 for the program)
 - 2 * 27C010 ROM (audio)
 - 1 * 27C512 ROM (audio)
 - 1 * GAL16V8 (PAL)

1.2) If you use a 91635B-2 B-board (mask ROM)
 - 8 * 27C400 ROM (graphics)
 - 2 * 27C4096 ROM (program)
 - 2 * 27C010 ROM (audio)
 - 1 * 27C512 ROM (audio)
 - 1 * GAL16V8 (PAL)

2) ROMs and PAL burning

Now it's time to burn the files on the appropriated devices.

2.1) If you use a 91634B-2 B-board (EPROM)
 - ROMs 01/02/03/04/05/06/07/08/20/21/22/23 => 27C4096
 - ROM 09 => 27C512
 - ROM 18/19 => 27C010
 - tk263b_1a.jed => GAL16V8

2.2) If you use a 91635B-2 B-board (mask ROM)
 - ROMs 01/02/03/04/05/06/07/08 => 27C400
 - ROMs 20/21/22/23 => 27C4096
 - ROM 09 => 27C512
 - ROM 18/19 => 27C010
 - tk263b_1a.jed => GAL16V8

3) ROMs installation

All SF2' ROMs must be removed from the B-board.
 The PAL named S963B at position 1A has to be removed too.
 Double check you've put the devices the right way (the silkscreen should help you)!

3.1) If you use a 91634B-2 B-board (EPROM)
 - Install the ROMs in the corresponding socket (ROM 01 in socket 01, etc.)
 - Install the GAL16V8 in position 1A (where the S963B was)

3.2) If you use a 91635B-2 B-board (mask ROM)
 - Install the ROMs 01/04/05/08/09/18/19/20/21/22/23 in the corresponding socket (ROM 01 in socket 01, etc.)
 - Install ROM 02 in socket 03
 - Install ROM 03 in socket 02
 - Install ROM 06 in socket 07
 - Install ROM 07 in socket 06
 - Install the GAL16V8 in position 1A (where the S963B was)

4) Test