Caius

Namco System 1 custom ’64A1′ replacement

Guides Comments Off

Mar 072015

First of all I want to thank JROK for providing me all the technical info and allowing its public release, without his help I would not have ever made.Let’s start with the story.

Some time ago a friend of mine sent me his Splatterhouse PCB bought as working saying it got stuck upon boot on ‘ROM TEST START!! PLEASE WAIT..’ message displayed upside down on a screen filled with red zero.So I started to investigate on the net and found that usually this kind of issues are caused by a faulty custom chip marked ’64A1′ @M4 on ROM board.This was confirmed by swapping this IC in another CPU board of Galaga88 with this missing component , in this case I got an ‘EEPROM ERROR’ message which is a further proof of the fault.

Thanks always to JROK we know that this ’64A1′ custom IC is nothing else than a HD63701 MCU with the exception of two custom opcodes not present in original part.You can go deeper into technical reading here:

https://www.jrok.com/hardware/cus60/cus60_an_owners_guide.html

So, programming a blank HD63701 MCU with the available dump from MAME won’t work due the presence of these two custom opcodes.So, patching a ROM is needed.

In the specific you have to change three bytes in the ROM “VOICE0” at a specific offset.For example : in Splatterhouse the offset is $FA8B and the new HEX values are “20 01 56”.

The string to search for in HEX is “B7 C0 00 6E 00” and the first 3 bytes must be changed to “20 01 56”

The patch seems to be needed at offset $FA8B for most games, but not all. Here’s a reference table :

PacMania -$FA8B
Tank Force – $FA29
Blazer – $FA8B
Dragon Spirit – $FA8B
Galaga 88 – $FA8B
Marchen Maze – $FA8B
Splatterhouse -$FA8B
Rompers – $FA8B
Blast Off – $FA8B
World Court – $FA8B
World Stadium (and WS ’89, WS ’90) – $FA8B
Bakutotsu Kijuutei (Baraduke 2) – $FA8B
Beraboh Man – $FA4E
Dangerous Seed – $FA8B
Face Off – $FA29
Pisto Daimyo no Bouken – $FA8B
Puzzle Club – no voice ROM !
Quester – $FA1B
Souko Ban Deluxe / Boxy Boy – $FA8B
Yokai Douchuuki (Shadowland) – $FA8B

So, it was only matter to find some real blank HD63701.My first attempt failed since I bought as new some ICs that they turned out to be already programmed and, since they were the plastic HD637B01VOP one-time-progfammable version, they were unusable for my purpose.But then I was luck and found some HD63701VOC UV erasable ones:

So, it was only matter to program one of these MCU with MAME dump using my Hi-Lo Systems ALL-11C EPROM programmer and, at the same time, replace the ROM ‘VOICE0’ with the properly patched one.Once done, I had confirmation of what the good JROK said about. Operation ‘NAMCO custom 64A1 replacement’ accomplished.

Altered Beast repair log

Mar 042015

Today I received a batch of some faulty PCBs and among them there was an original Altered Beast boardset:

Once fired up all was working fine except for the colors, they were clearly wrong (kinda pinkish):

For first I went into TEST mode.In all Sega System16 games(that support it) you can enter in TEST mode by pressing down at same time TEST,SERVICE and P1 start switches.But color RAM test was passed successfully:

Near the two 6264 color RAM @J9 and J10 I noticed a couple of 74HC273 which input were connect to data BUS of the RAMs (as they latch input data).Probing the one @L11 revealed some outputs stuck HIGH though inputs were toggling fine.Piggybacked it and colors came to normal (well, almost, sky apart) :

Time to desoldering and testing it out-of-circuit:

Replaced it and board was 100% fixed.Job done.

Wonder 3 (Japan 910520) PAL dump added

PAL Updates Comments Off

Feb 152015

Today I converted to GAL16V8 the binary PAL dump ‘rt22b.1a’ from the MAME ‘wonder3’ set and Silvio Grazini successfully tested it on his CPS1 board.JED was added to database.Thanks both to him and the original dumper.

Rally Bike repair log

PCB Repair Logs, Repair Logs 3 Responses »

Feb 152015

Got this original Taito/Toaplan Rally Bike PCB for cheap:

Seller claimed that it was working fine except that it didn’t coin up with both players.So, I was confident that it would have been an easy repair (but in hindsight I can say not really..).

When I started my troubleshooting I found none of the inputs (and dispwitches, too) were working.Checking all JAMMA connector pins with a logic probe revealed they were all fine (high when input is not activated and low when button/direction switch is pressed) so resistors arrays were doing their job but something happened after and the signals could be not propagated.Tracing back the inputs I found that they were tied to inputs of some 74LS240 near the JAMMA connector.Probing them revealed that outputs didn’t change they state when inputs were activated because all the enable pin (PIN1 and PIN19) were stuck high.All these enable signals were tied to some outputs of a 74LS138 which I tested good out-of-circuit.So, I was in a dead end and giving up but doing some research about Toaplan hardware I came across this page:

https://allyourbase.toaplan.org/hardware/index.html

where it said that Z80 audio CPU handles not only sound control but also all I/O reading:

So I started to probe the digital audio circuit and found thath some address lines of Z80 (and so also of the connected RAM/ROM) were stuck low as well all data lines of the YM3812 sound synthesis chip were in high impedance state due the /CS pin stuck high.The audio ROM was dumped fine and piggybackinbg the 6161 RAM had no changes at all but when I made it over the YM3812 suddenly the game coined up and started a game.I swapped it for a good one and all the inputs were working again.But sound was totally missing, only some hissing noise sign that the main MB3730 amplifier was good at least.Since digital part of audio circuit was fine, the fault was located in analog section.Probing the YM3014 DAC and the LM358 OP-AMP I could measure only 2.45V across their power pins sign that there was almost a short on thes two ICs:

Infact, after removing them, I could measure the right voltage on the power pads:

Replaced both YM3014 and LM358 restored full sound.End of job.

SEGA System 2 PLD update

PAL Updates Comments Off

Feb 062015

Today I had the chance to try the existing PAL dump of the PAL16R4 marked ‘315-5138’ @IC11 on a Sega System 2 Shooting Master PCB and I can confirm it’s working also on this board (so it’s not exclusive to Choplifter).Besides, I converted in GAL16V8 format the MAME dump of the other PAL16R4 ‘315-5137’ @IC10 and tested it as good.Finally, I converted the ‘315-5139’ PLS153 dump made by Porchy into CK2605 original device fusemap using the Charles MacDonald PLAD utility and then successfully reversed it to GAL16V8 format.Database has been updated.

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