PCB Repair Logs – Page 105

SEGA Tetris repair log

Feb 022013

Got a Tetris that was sold as faulty.
As with pretty much any PCB I buy, a visual check was carried out and straight away I found this capacitor.

The board came with an adapter but looked a mess and the wire was far too thin on the power lines so I swapped it out.
I also found a couple of pins touching in one of the unused connectors

And finally I found the sound pot was no soldered in at all and was missing its ground pin.

I took a pot from an old scrap board and fitted it.

Now it was boot up time.

All looks ok so far, but…..

I initially thought it was a dodgy EPROM but they checked out fine. Then I realised that the EPROM at location B1 on the ROM board was missing.

I burned a new one from the Jap set and now we have this.

Everything seems to be working fine.
This board still has its battery installed in the FD1094 and surely will be coming to the end of its life by now. I don’t trust myself with a battery change but I think I have desuicided ROM’s so will just wait until it dies completely or I will sell it on as I cant imagine wanting to play this in my cab.

Pac-Man repair log #1

Jan 202013

Quite a few weeks ago I took part in a charity event which saw me win a personalised copy of Pac Manic Miner Man written by Jim Bagley and runs on original Pac-Man hardware.
My good friend Equites from the J+ forums hooked me up with an original Pac-Man board and after making up a jamma adapter it was clear some repairs were needed.

The board has 2 daughter boards for the custom chips, one of them being a 3rd party one.

A quick inspection revealed this

I reseated the the sub board and the game booted to random garbage on screen

The boards watchdog was also “barking” so I check the 4 program ROMs, all of which were recognised by MAME.
This was the ideal time to hook up the Fluke 9010 and see what was going on.
First off it showed me that the RESET line was active so I told the Fluke to ignore it.
I carried out BUS and ROM checks. All of which returned OK. I tried to carry out RAM tests and DIP switch tests but I couldnt read anything back other that “F7”.
Something was wrong at address line 14 and it pointed towards the 3rd party sync bus PCB. Equites confirmed that the previous owner of the board had this module plugged in backwards so that confirmed my suspicions.
Andyman from the J+ forum also showed me a picture of what his look like without the Sync Bus PCB attached and it was identical.

I spent quite a bit of time wondering the best way to tackle this. I could buy another 3rd party module, or, as the schematics for a TTL version are available I could build my own. My saviour came in the form of the fantastic reprogrammable device from FPGAARCADE.COM.
I have a spare here that is currently programmed with the Commodore 64 PLA replacement but I do have the tools required to reprogram it. What I didnt have was the code to program it with. A quick email to Mike, the owner of FPGAARCADE and he sent me the file required.
Once I had the chip reprogrammed (took ages as my current programmer didnt want to bother working) I fitted the device and….

As all the RAM chips are socketed I pulled them and tested them. The 2114 RAM at position 4R can back as failed. I have some spares of these so fitted a new one and fired the board up again.

SUCCESS!
This game will sometimes be running Jim Bagleys Pac Manic Miner Man so now was an ideal time to try the ROMs out on the actual hardware.

Very happy to get this running.

Thanks to:
Equites for the PCB
Mike at FPGAARCADE for the Sync Bus program file
Andyman for help diagnosing
Jim Bagley for creating PMMM

Caveman Ninja repair log

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Dec 092012

Where to start with this one.
My good friend brought this round a while ago with the fault of jailbars down the screen and no sound.
After messing around a bit we couldnt even get the game to boot on my setup no matter what we tried. He left it with me and ive been chipping away at it for a month or two now whenever I get time.
Ive finally got this thing up and running.
First this I found was two PLD’s, TJ-0 and TJ-1, were getting really hot.
As I have a couple of spare Caveman Ninja boards I did a swap and the game booted. Strange thing though, those PLD’s actually work in my other semi working board.
So now we have this

and no sound was present either.
Jailbars are usually a sign of a failed ROM so off the the tile ROM’s I go.
Found MASKROM MAG-02 had a few floating data pins. Replaced this for one off my scrap board and we get this

Graphics are back. Now onto the sound.
Looking first at the two OKI M6295 chips I could see neither of these were being enabled. If I pulsed the enable lines I could get various sounds to play. This tested the rest of the sound circuit so I knew it was good.
I traced the enable lines back to a 74LS138 decoder which wasn’t doing a great deal despite having what looked like good inputs. I removed this and it was indeed dead so replaced with a new one.

Still no sound though.
I could see the sound CPU and ROM were being addressed properly so next up was the RAM. On this board it was a TMM2063 chip. I could see activity on the data lines but it was struggling to drive them up to logic HIGH so removed that and that too failed a test.

I replaced it with a CXK5864 chip. Still no sound.

I started looking into how the sound section worked and found that the custom 104 protection chip is responsible for activating the sound.
I got in touch with a guy called Bryan who wrote the MAME driver and he gave me some nice information of its operation and basically pin pointed my issue to this chip.
At first I tried reflowing the pins but it made no difference so after a bit of debate with myself I took the plunge and removed the chip

I replaced it with one from my scrap board. WE HAVE SOUND!

And thats it, or so one would think. After about 2 minutes of playing this game, some of the sprites started to go a little crazy.

Going over the sprite ROM’s I found another one (MAG-06) with a floating data line. Replaced this with a spare and all is well once again.

Without a scrap board to take customs from this would have been one for the scrap pile.

Captain Commando repair log

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Nov 052012

This is one from quite a while ago that was forgotten about and I was only reminded of it recently by a a guy asking some questions about the PAL CCPRG I have here.
I got this game in a job lot of CPS1 stuff ages ago. It has the EPROM’s missing and 2 of the graphics maskroms were also missing.
First thing I noticed was the maskroms were in a strange order.
If you look at the MAME source code for the CPS1 driver you will see some comments next to the ROM order.

As the maskrom’s are not JEDEC, I filled the missing sockets with 27c4100 EPROM’s with the correct code.
As for the missing EPROM’s for sound and program ROMs, not including the two 27c4096 ones, the silkscreen said to use 27c301’s. Who am I to argue with that?
I burned all the remaining EPROM’s, modified the C board to run with the suicided code and fired it up.
Nothing!

C board was dead so fitted one from an old Street Fighter 2 CE and got this

I end up with most of the graphics being garbage and no sound.
This took me a while to figure out but in the end I should have ignored the silkscreen as the jumpers on board were set to accept JEDEC program ROM’s. I could have changed the jumper but decided just to burn new sound and program ROM’s instead. Now the sound and graphics were all fine.

I dumped the PAL’s that were on this too.
Fast forward to a few days ago and I get an email telling me the CCPRG PAL doesn’t work. Strange as it works for me. I reburned the GAL and tested but got nothing but a black screen.
Not sure what happened when I originally uploaded the PAL but I uploaded the wrong one. This has now been sorted and fully tested.
Thanks to Robotype for pointing this out to me and persisting with it when I didn’t really believe him.

Street Fighter Zero 2 repair log #2

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Aug 192012

I wasn’t originally going to write this up but seeing as though I won’t have much time free in a few weeks I thought I might as well.
So, this game would hang at the Q Sound check at startup. After a quick check I found why.

I straightened the pin and the game now works.

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