Dead Gorf - need help

[gb3199]

Hey all, I'm hoping someone can help. I just picked up a dead Gorf. Here's the deal, when I fire it up the screen is blank and I can hear an intemittent beeping sound.
Is this the sure sign the boards are bad? I went through all six boards and fixed a couple of visual problems - chips that weren't properly seated, etc. Also I tried to enter the test mode, but was unable as the screen remained blank and the soft beeping sound continued. Has anyone experienced this problem and what would you recommend? Thanks in advance.

 

[Mongo]

I have owned several Gorfs. Luckily I had a couple of spare board sets and was able to play "mix and match" until I had one complete working set. Then I just tried one board at a time to identify which of my spares was bad. My sets are long gone now or I would help you out....

First thing I would do is verify the voltage at the connector on the bottom of the PCB cage. Each pin is silked with the correct voltage next to it. That connector is prone to corrosion and heat damage so just plain old power could be your problem...

 

[gb3199]

Thanks for the advice, I will do that. Barring that I'll begin my quest for a working set of boards.

 

[KenLayton]

Yes, start by checking for bum connectors and then have a look-see at the power supply board. Check all fuses to see if there's a bad one.

 

[gb3199]

Hey all, need a little more help, I think I'm close, I actually heard GORF talk today.
Got the boards, went through them and figured out that the second one on my original set was bad. Great, I swap out the dead board and fire it up and the graphics are kind of garbled when the word GORF comes on the screen. But when the text scrolls down, it's fine. When I try to play a game, no dice.
Now here's the weird part.
When I go into test mode, eventually the test screen will come up, indicating that everything is well. But sometimes I have to wait and the lines are on the screen indicating that the ram board is faulty.
Then as soon as I go back into the game, its the same story as before. No game play, it just locks up on the first stage.
Now I've got six ram boards that I've swapped in and out to see if two will work, but I can't get the right combination. All that said I have a sneaking suspicion that it's the second board of the six that's crappy, or there's some other loose connection somewhere along the way. I've cleaned all the connection and the connector at the bottom of the cage, just to make. And the cage is getting power.
Does anyone have any ideas? PLEASE, PLEASE, PLEASE!
Thanks in advance.

 

[Mongo]

I never really trusted the GORF self-test. Those RAM boards are VERY prone to failure. One of my bad RAM boards would put horizontal lines across the screen.

I just repaired a GORF that locked up at the second stage. A simple ROM was the problem. Evidently, ROMs are a semi-common failure with them too. Do you have the ability to check your ROMs? If not, I can check them for you.

Just for the record, the Midway card cage system was used on other games as well. If Gorf PCB sets are too expensive... try watching for a Wizard of Wor set.

 

[gb3199]

Well I'm not quite at my wits end, yet. I think you're right about some of the roms possible being bad, the question is which one(s). I have two sets of complete boards, and two extra ram boards. SO I should have enough stuff to mix and match, I'm just not sure where to start. I just realized that there are some differences between the two main boards I have, as in the number of chips. But I don't think I'm too far off, it's close. Or I can just buy another set of boards that are guaranteed to work and start all over again.

 

[Mongo]

On your main PCB, you will notice a socketed jumper "chip". Depending on the type of ROMs being used, some of the jumpers get cut. I seem to remember an 8 chip set and a 4 chip set. The 4 chip set had the jumpers cut I think.

I have the code for the 8 chip set which are all 2532s. When I did the checksum test on the last one I repaired, I found one chip with a bad checksum and another tested good but on close inspection, a couple of the leg "tips" were broken off. They seemed to be long enough to make good contact but leaving it in was a recipe for intermittant failure. I had to change the socket as well because the leg tips were still in the holes...

 

[gb3199]

Yes, one has the eight and the other has the four, just as you explained. I'd ask for the code but I don't have a eprom burner. Can you do it and how much would it cost?

 

[Mongo]

Check your PM's...

 

[gb3199]

Finally got Gorf working today!!! To make a long story short, the ICs on one board were bad, while the roms on the other board were dead. I combined the best of both and I now have a working Gorf. All I have left is to fix the Space Cadet light, and from reading another posting, I think it should be an easy fix. Thanks to everyone for their help.