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.

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

 Patched files for sale, contact apocalypse-mods@outlook.co.nz

28 Mar 2018

Baraduke (Alien Sector) - Namco 1985

Game was stuck on a static garbage screen:

This hardware is full of custom chips so I started the repair with a bit of apprehension.
Luckily it turned out to be really easy to fix, I even didn't need my soldering iron.
I started by probing the main CPU (6809), reset signal was OK, clock was present but data and address buses were totally silent.
Most of the chips were on sockets so I dropped a new CPU, and game booted:

Game fixed.

21 Mar 2018

Street Fighter - Capcom 1987 (repair log)

The first Street Fighter from Capcom, not so common.
First version had 2 "air" buttons (punch & kick) acting as analog inputs (the more pressure, the stronger the punch/kick) with hoses connected directly to the top PCB (game is a massive 3 board stack). Then they changed the design to the now very common and popular 6 button layout (low/medium/high punch/kick) as some players used to abuse the cabinet (even jumping on the buttons!). This is the version I own (Japanese with protection).
Boards were in good condition, however I quickly noticed they were full of Fujitsu chips. A painful job in perspective (or soul crushing as my friend Kelvin like to say).

I powered the board and it did nothing more than a black screen.
I started the repair with the bottom board as it contains the main CPU.

1) Fixing the bottom board: main CPU/background

Probing the buses revealed the CPU (68k) quickly switched in high impedance. Program ROMs and work RAMs (2 * 62256) were fine, board was clean with no visible severed traces so I went to probe the logic between them (mostly LS2455). I couldn't test them properly, being tri-state and bi-directional IC. I chose to remove all the TTL chips from Fujitsu in the CPU area: 2 LS245 turned out to be bad.
After replacing them the game booted but with many issues (again I forgot to take a picture):
- highly corrupted background
- no sprites
- wrong colours
- sound was present but with a cyclic click noise
I probed the rest of the bottom board and found many other dead Fujitsu chips:
- 5 * LS86
- 1 * LS138
- 1 * LS174
- 2 * LS273
- 1 * LS367
I fitted new parts and this fixed the background:

2) Fixing the top board: colours and sound

I then moved to the top board rather than the middle board as I wanted to be sure the wrong colours weren't hidding something else.

Yes you guessed right, more dead Fujitsu TTL:
- 1 * LS174
- 1 * LS245
But that was not all, one of the colour RAMs was dead too (CXK5814 = 6116 type).
Colours were now OK, so as title screen.

3) Fixing the middle board: sprites

With the background and colours now correct I could see the sprites were not totally absent:

Again dead Fujitsu TTL:
- 3 * LS86

But replacing them had no visible impact on sprites.
So I moved on the next probable culprits: shiny RAMs. They were 6 of them on that board and 2 were dead (TMM2015 = 6116 type).
This time sprites were fully restored:

Game fixed.

- 8 * LS86
- 1 * LS138
- 1 * LS157
- 2 * LS174
- 3 * LS245
- 2 * LS273
- 1 * LS367
- 2 * TMM2015
- 1 * CXK5814

14 Mar 2018

Lethal Enforcers - Konami 1992 (repair log)

As usual with the Konami boards of this era, the SMD capacitors on the custom audio module have leaked resulting in a mute game.

First thing to do is to remove the black paint. In my case it was not too hard, the electrolyte leakage had degraded the paint. I rubbed the concerned areas with a toothbrush:

Then I removed the faulty capacitors:

I've made a small schematic to help you identify the capacitors polarity and value:

As expected once replaced the game works just perfectly fine.

Game fixed.

7 Mar 2018

Renegade - Taito 1986 (repair log)

Another game which was previously worked on: I noticed few chips have been reflowed.
Otherwise the 2 boards looked fine to me so I powered the game. It was stuck on a static screen with a border of a different colour:

I could coin the game and hear the associated voice sample but only once. Nothing more (game wasn't playing blind).
I dumped the ROMs and found the one named NA-5 (IC52) was corrupted. I reburnt it and game booted with no other problem:

Game fixed.