Build Your Own Arcade Controls Forum
Main => Main Forum => Topic started by: dmel75 on June 15, 2009, 07:27:19 am
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My Gorf cab is gutted and ready for painting so I decided to give the game troubleshooting a try again.
(http://i594.photobucket.com/albums/tt23/derekmelton/CIMG5725.jpg)
I set everything up in a testing setup and tried again but got the same results.
I took a Youtube video in hopes that maybe someone else seeing what was going on would help. [youtube]http://www.youtube.com/watch?v=gNntrX3KKsk[/youtube] Take a look and if you have any ideas please let me know!!
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Does the sound work while the video isnt?
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Not familiar with Gorf in particular..... but same as in all game trouble shooting.....
You definitely appear to be having a game pcb issue.
I would start by taking one board at a time and pulling it out and re-seating and cleaning any "socketed" chips. Since you've had Gorf pop up before, you may just have a bad chip connection/socket somewhere.
Verify continuity from the chip legs through the socket to the solder side of the boards.
Of course do this carefully and watch for badly corroded chip legs that may break off.
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You have a PCB board failure. The main suspect is the board with the Z80 CPU on it. IIRC it also has 3 custom Astrocade chips on it. The Data chip is the workhorse and the one most likely to have failed. They begin to fail after around 20 years. The chips can only be replaced with chips from original boards, but you can also use boards from Wizard of Wor cages. The board you're after is very distinctive. Its not the one with cables connected to it and has the three large 40 pin chips arranged down the middle of the PCB with the 40 pin Z80 off to one side.
Take a look at that main board and see if the data chip has a spider like heatsink on it. In the early days when the original boards began to fail the manufacturers began to fit these heatsinks to the data chip. You still get failures though, but if there is no heatsink its 99% likely that its the data chip. If I were you I'd remove the 3 custom chips and Z80, clean up the legs and refit. This sometimes works, but maybe only 1 out of ten times on the many boards I've had over the years.
Frustratingly no one that I am aware of has recreated the custom Astrocade chips unfortunately. The best you can usually do (as I have done) is to buy a card cage and set of PCB's from Ebay, but these are usually always sold as 'untested', which normally means that they don't work. This means its luck of the draw unfortunately. FYI The boards can be replaced in any order, as the bottom of the cage is a simple connecting bus.
The other boards do fail particularly the two smaller memory boards, but you would normally still get the game firing up with graphical corruption of the on screen entities.
When \ if you do get a working board set, immediately buy some low profile heatsinks and glue them to those 3 custom chips and the Z80. On my card cage I have mounted some small PC fans above the card cage to keep the chips cool. These can be wired straight in to the switching power supply. This mod would have saved at lot of Gorf boardsets over the years :'(