23 May 2018

Sega 834-6510 I/O board reproduction - part 1

As far as I know this board is used only on System 24 for driving games (Hot Rod and Rough Racer) and golf games (Jumbo Ozaki Masters and Dynamic Country Club).
It handles analog inputs (e.g. steering wheels, gas and brake pedals, etc.).

I've been looking for one for a very long time and finally took the decision to reproduce it. Still it wasn't easy to find an original board as model for my reproduction.
Once again a German collector came to my rescue and lent me his board:

And here's my CAD reproduction:

It's quite expensive to build due to ICs used being dropped for a long time (D4701, M5203).

16 May 2018

Xexex - Konami 1991 (repair log)

PCB was in very good condition but threw a "SOUND MEMORY BAD" error on boot up:

Of course this error isn't in the manual and even after an extensive online search I haven't found any mention of it anywhere...
Well after some probing and testing I came to the conclusion it had nothing to do with the RAM chips on the mainboard. I mistakenly thought it was caused by a bad '054539' custom chip (samples player) so bought a replacement pulled from an other game from Caius @ jammarcade.

I pulled the suspected faulty chip and cleaned the pads:

Then I aligned the replacement chip and soldered the 4 corners:

Then applied some SMD soldering paste:

And used hot air for soldering:

Only to discover it didn't change anything regarding behaviour of the board, still stuck on the same error.
So I had a look in the code and found this error is reported when the RAM present on the custom sound module is bad. Many of you know there isn't any RAM on this module but instead there's a '054321' custom chip handling, amongst other things, sound volume. I came to the conclusion the chip embed some RAM, which makes sense.
I swapped the sound module with a working one and indeed fault followed the suspected faulty one. I went even a step further and swapped the '054321' custom chips between modules: and boom we've got a culprit, the '054321' was obviously faulty.

Game fixed in a sense (although I don't have any spare '054321', at least fault is identified, it's just a matter of soldering a good chip now).

I then had an other discussion with Caius who told me he encountered similar symptoms on a Bucky'O Hare board few days later:

Damn it... I should have waited few more days before starting this repair.

9 May 2018

Super Pang - Capcom_Mitchell 1990 (repair log)

An other suicided game with additional problem: instead of the ligth blue screen the suicided game should display I was greeted by a black screen...

I followed the desuicide procedure found on the "Dead Battery Society" website (http://www.arcadecollecting.com/dead/), and then fired the board: black screen just as before but audio and controls were working. Game was playing blind, I could add credits and start a new game.
When you have no video at all it's always good to start from the JAMMA connector and then follow the signals. In this case red, green and blue signals on the edge connector were stuck low. I then probed the colours RAMs (two of them) @ 8C & 9C: all data pins were stuck low. I took the chance of piggybacking them and obtained an image. Colours were not perfect but this is something to expect when you piggyback chips as the faulty chips underneath can drag the signals low or high and the connections aren't at their best.

I pulled the faulty RAMs and both turned out to be fried on my programmer. I installed sockets and put fresh RAMs in them and was greeted by a fully working game:

Game fixed.

2 May 2018

Cal.50 - SETA 1989 (repair log)

An other greasy board covered by CRC. I first cleaned it after removing all the socketed chips and the battery (used for high scores saving).

Once the board was completely dry I tested it: game was dead, sync signal wasn't valid.
Probing the main CPU (68k) I found reset signal was held low. There's a reset button on this board so I had a look at it: I tested continuity and it turned out it was stuck depressed. I replaced it but saw no improvement. Next to it was a voltage control chip named "RE5VA45AC". It was dead too, possibly because the button has been kept depressed for a long time when it's supposed to be just an impulsion. I couldn't find a replacement part for it so I simply removed it and bridged pins 1 & 2 which was enough to repair the game:

Game fixed.

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