GORF screen error and glitch

Vongoosewink

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I had my first arcade party last Saturday, and one of the games in the line-up that got a lot of play was GORF. The machine held it's own the entire night, but as we were getting ready to shut down, we noticed a screen error on the game.

The screen has several horizontal lines missing and some repeating (partially repeating the same line of text).

If you quarter up, the game starts to play, and your ship immediately blows up -- all the while, Gorf is mocking you.

Not too sure what to make of this, anyone ever experience a similar error? (Pictures below).
 

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Always start by checking the voltages at the board (not at the power supply), after that it could be a socketed chip that is not making good connection, ribbon cables that need a reseat or an actual fault with one of the RAM chips or associated logic.

Address the simple things first tho.
 
That is either one of the two smaller RAM boards, or possibly the Pattern board.

I'd bet on one of the RAM boards since GORF uses a collision detection scheme that will generate errors and false hits if either one or both RAM boards has an issue.

Those are interchangeable, so you can swap their positions and see if the lines move- then you'll know you've located the issue. Depending on if you have access to a ROM burner, there is a test ROM floating around the net that will display specifically which RAM chip is to blame. They're not socketed so you'll need to de-solder the offending chip and replace it.

If you're board skills aren't up for that, just grab another RAM board, or an "untested" set off eBay and you'll likely get at least one working RAM board out of it.

Post a follow up and let us know what happens.
 
Thanks guys, I took this in to Ed Lutz at Arcade Odyssey in Louisville, KY, and he fixed it for me in just a few minutes!

He really knows his Gorf games!
 
Anyone keeping score.....it was a two fold problem. The main issue was a bad custom address bus chip. That resolved the crashing and "lines" issues. There was some sprite tearing caused by dirty edge connectors in the bottom of the cage.

Edward
 
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