Porchy

Time Pilot diagnostic ROM update

Jul 172015

Im currently working on a Time Pilot PCB and tested out Shoestrings diagnostic ROM.
This board is the Atari version which wasnt supported at the time but has now been updated.
I also ran into a problem where nothing appeared on the screen. Working together we eventually found the issue.
The original game code makes a write of 01 to address $c308. Using the Fluke 9010 I found that this write actually initialises the screen output.
MAME doesnt have any support for this so when testing the ROM in MAME it works fine. The test ROM has been updated with this now too and should work fine.

This highlights the need to test things on REAL hardware.
Thanks to Shoestring for making the diagnostic ROM and for putting up with all my questions.

5 Year Anniversary!

General 12 Responses »

Jul 112015

JAMMArcade.net is 5 years old!
I never would have thought 5 years ago that this blog would still be going today let alone be the project that it turned into.
Here is a brief history of the how this whole thing started.

It originally started out as a way for me to document my journey into building a home arcade and maybe provide other new starters with some basic information.
The arcade collecting part never lasted too long as the repair bug hit me and I ended up preferring repairing boards over actually playing them. This is where my obsession with PAL’s also started.

I found it really annoying that an otherwise good PCB had to be scrapped because one little 20 pin IC was dead and the code contained within it was lost. On my search for elusive JED files I found a small ZIP file with a few dumps in it and I also found a few more on Macro’s website. The later is where I read about a device called the Boardmaster 4000 which was apparently able to dump PAL chips.

I eventually found a Boardmaster on eBay (back when a bargain could be found) and that’s when I started dumping PAL’s. I dumped pretty much everything I had and around the same time started the Archive on this website. Pretty soon I started to think “what if the Boardmaster breaks down?”
The Boardmaster program was heavily based on the work of Charles MacDonald who had built a standalone device.
I had soon built his PAL dumper hardware and was ready to stop using the BM4K for dumping.

Shortly after I started adding PAL dumps I started getting people send their own private collection of JED files and the list started growing. Caius was one such donator and was sending them on a regular basis. It made sense to me to ask him to join my crusade so he did and now we have an excellent repository for PAL dumps, something which we are both very proud of.

I cant recall the exact date but it seems quite a while ago now that Runik joined the site.
After trying unsuccessfully to get the decrypted code for his Golden Axe game via the usual channels, he took it upon himself to learn how to decrypt the games. Not long after that he managed it and I guess there is little else to tell of that story.

More recently a few more people expressed an interest in contributing to the website and I’m very happy with it. There is a ton of information on it and having multiple people posting repair logs really does show how different people approach problems and faults. While its rare that a repair log will be the exact same fault a different person may have, it can at least give others ideas on how to start doing repairs of their own.

I’d like to make a special mention about Shoestring’s excellent self test ROM’s for Konami games and also his Konami-1 assembler.

That’s about all there is to say. I hope we are still going in another 5 years.
Thanks to all the people who contribute to the site and everyone that visits.

Special thanks goes to Charles MacDonald who without I would have never been able to start dumping PAL’s and is often the source of help when I’m trying to make sense of things.

Also a massive thanks to Muddymusic who has hosted this site for the last 12 months when my old provider, Servage.net, decided they couldn’t be bothered to deal with issues on their own servers.

So what’s in store for the future?
No idea really. Hopefully most things will carry on the way it has been.
I do a lot less repairing these days and focus more on the electronics side of things (arcade/retro related).
I recently made a homebrew cartridge for the GameKing handheld system in order to test the dumps myself and Team Europe have made.
I also teamed up with cmonkey not too long ago to make a mod for Outrun which saw the two new tracks found in the newly released 3DS version make their way into the original arcade version. cmonkey did the software side of things and I handled the new bankswitching that was required and also made the ROM adapter for it.

Other ongoing projects I have are a completely over the top supergun and I am also working on a couple of cabs too.

Hopefully the rest of the team continue to contribute and expand the site further.

Hi-Lo EPP-01A EPROM Programmer PAL’s added

PAL Updates Comments Off

Jun 192015

Recently I was given a bunch of old programmers and things from a friend that was doing a clear out.
Among them was an old Hi-Lo System EPP-01A programmer which happened to have 3 x PALCE16V8 devices in it. All of them were locked and I don’t have the relevant ISA card to test the actual programmer out so these are untested. They don’t look too complicated though so im sure they will work just fine.

Pang repair log #2

PCB Repair Logs, Repair Logs Comments Off

Jun 162015

Got a friends Pang PCB here for repair.
He had carried out the ROM swap (made by ArcadeHacker) to desuicide it but he had no output although we could hear it playing blind.
The board is very clean and a visual check revealed nothing.
On powering the board up I got this screen

I could also hear the board did play blind so that’s a good sign.
I like to make little schematics for boards when I’m working on them and they don’t have any available and I quickly came up with this.

I started probing back from the RED pin on the JAMMA edge connector and soon came to a RAM chip at location 8C. Probing this chip and its counterpart gave me some odd looking signals which I got suspicious about.
These chips are CXK5814 SRAM chips and they seem the be the most unreliable RAM by comparison.
One of the RAM’s had all its data lines stuck LOW while the other chips data lines were all dead despite all the enable lines working as they should and the address lines active.
At this point I was certain they were dead but one last test was to ‘piggyback’ a known good RAM chip on top of the suspected bad one. I chose the one with the dead data lines to avoid potential contention and I got a partial image on screen.

I desoldered both the RAM chips and replaced them. I didnt have any spares in my RAM bin but found a couple of skinny 6116 RAM’s on a scrap bootleg board.