Atari Dunk Shot to Tehkan World Cup Update 2

 Tehkan World Cup  Comments Off on Atari Dunk Shot to Tehkan World Cup Update 2
Jul 292018
 

My conversion to Tehkan World Cup is progressing well……

Since my last update I’ve managed to apply all the artwork on the cabinet and add the trackballs and buttons to the control panel.

This was taken after applying the artwork to one side of the cabinet, and laying the internal monitor bezel graphics. The control panels are not done at this point:

TWC Full Art Side

This is after all the artwork is applied:

TWC Full Picture

TWC Control Panel

Next stage is to wire everything in and then power up the game and see if everything works ok!

Super Cobra Repair

 My Projects  Comments Off on Super Cobra Repair
Jul 292018
 

Bought a Super Cobra PCB that was meant to be fully working, but of course wasn’t. It was too much hassle to return to the seller, and I wanted the PCB so I decided to fix it.

First issue was corrupt graphics in-game and the board could not run a Super Cobra test rom correctly

Test Rom Video

The test rom was failing at the screen ram test, so I checked the rams on the main board and found that a 2114 @ 3K had failed so replaced that and got all the GFX back

Next was the audio. To help with this I built Phil Murrs audio probe here which was very useful!

I was getting a low pitch, really loud noise, when I powered up the PCB. It is quite horrendous! Adjusting the volume pot just seemed to make things worse

I checked the z80 on the top board, and the ram. I took the checksums on the roms which I need to check later. I popped out the AY chips, and the 8255 chips and the sound was still the same.

Clearly the amp was working because I am getting some noise!

Next I checked the outputs from the AY chips CH A, B & C – pins 3,4,38 with the audio probe and got nothing.

I checked over the z80 CPU which seemed ok.

Turned my attention to the 8255 chips. Popped them both out again and noticed a bent leg on one of them. Straightened the leg and the game sounds now returned when testing with the audio probe. I then tested the board properly on a cab and everything was working fine

Thanks to PhilMurr for his help

Now to do the multi-game board 🙂

Vs. Goonies/Gradius PCB

 Nintendo Vs  Comments Off on Vs. Goonies/Gradius PCB
Apr 022018
 

I’ve been busy working on a reproduction Vs. Goonies/Gradius daughterboard for the Nintendo Vs. system.

There were complexities to this PCB because it uses a custom VRC chip, which are not easy to find, and there are no schematics for this board so it was a case of tracking down an original PCB, and mapping out all the pinouts. The great thing is that this PCB will be a lot less than an original PCB, so it makes it cheap and more available for the people that would love to own it, like myself 🙂

This is the circuit diagram I produced using Eagle:

Vs Goonies PCB

Vs Goonies/Gradius PCB

The boards arrived from manufacture to be tested:

Boards Arrive

Boards Arrive

Early version of Tehkan World Cup

 Tehkan World Cup  Comments Off on Early version of Tehkan World Cup
Jul 292017
 

I’ve been working on trying to fix an original Tehkan World Cup PCB for quite some time, but not making much headway.

What has been really interesting about this repair is that I have discovered that the majority of the roms on the main CPU board were not known in Mame. Sometimes this is just a case of the rom data being corrupt, but I have managed to run the game data in Mame, and it looked fine, so that ruled that possibility out. What I noticed is that it was different to the version I had previously seen. I compared the two side by side so you can see the differences yourself. You’ll notice that the logo looks different and there is no world cup image in my version:

YouTube Comparison

With the help of another collector I submitted the rom data to the Mame team and it turns out that this is an early version of the game and even has a different way of handling the dip switches.

The information that was added to Mame can be seen at the page below:

Mame Tehkan World Cup Info

I also submitted some pictures of the CPU and video board to the Mame team so they were aware of any markings on the board which might provide some more information:

Tehkan WC CPU Board

Tehkan WC Video Board