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 🙂