| Arcade Collecting > Restorations & repair |
| Gorf Restoration |
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| Scottacus:
I've never owned or refurbished an arcade game but I've always wanted to get a Gorf game for the basement. My buddies and I fed way too many quarters into these in the early 80's and I figured that this game would still be fresh today because of its multiple games within a game. I found one within a couple hundred miles of us for sale on Craigslist and was a little dismayed at what kind of shape it was in. The entire machine was covered with grime inside and out, there were even dried leaves in the base of the cabinet. Some repair man had cut out several of the light fixtures and there were exposed line voltage wires inside the cab. The control panel was badly scratched up, the lens for the joystick was caved in, the plastic sponson on the back that protected the CRT neck was cracked in one corner, all of the locks and coin mechs were missing, one of the leg levelers was torn off and the side art was gouged. The good news was that the game would power on, drive the monitor and make some sounds. When power was first applied, the coin counter went crazy and kept registering coin ups but that went away after the power was removed and restarted. The ship would drift to the left and not move up or down but the fire button worked and the game seemed to play correctly. The test screen showed that the move left and down controls were both stuck on but all of the other switches were functional. I guess I really wanted a Gorf game because I ended up buying it and lugging it home in the back of our minivan. I had found a GREAT refurbish article on this site by Spyridon that can be found here http://forum.arcadecontrols.com/index.php?topic=80733.0 so I had a good idea of what was on the inside of the Gorf game before I bought the game. I won't go through all of the gory details of the refurbish here since Spyridon has already covered that but I will go through the bits of my refurbish that were different to help anyone else who might benefit from my experiences. here is a link to the Gorf manuals and schematics http://www.arcade-museum.com/game_detail.php?game_id=7983 from KLOV. These were invaluable in trouble shooting the machine. More to follow... |
| Generic Eric:
Sounds cool. The more gorey the details the better. Get the smell-o-net plugin for chrome to upload the funk from the mold. And pics, lots of pics. If you are worried about hosting them, upload them to this thread. That way when yahoo goes under and no one buys flickr, we can still see your pics. |
| Scottacus:
Sorry I can't upload the smells but I did have Vincent Price's line from Thriller going through my head as I cleaned out the cab as he said "the funk of 40,000 years...". Here are some photos of the game in the condition that I found it. Starting with the cabinet, over all it was in pretty fair shape. There were some deep gouges in the sides and the artwork had been defaced but structurally everything was pretty good except for a little rot on the base corners of the cab. The instructions had been worn off from the metal panel that sits under the joystick Some of the lighting wires had been cut and taped off and others like the purple one here were just sitting there waiting to fry someone with line voltage. I didn't know about this until I took the cab apart but of course I made the game safe first! The inside was pretty well grunged up and had leaves and lots of fasteners that the repair guys lost or tossed. The one that nearly gave me a stroke was this little screw sitting in the bottom of the metal enclosure for the boards! I tried the game at the warehouse where I bought it and transported it home on its side. If that screw had slid around and shorted out one of the boards to the metal chassis I would have been royally screwed! I was very fortunate to not have more problems on my hands but between the hot wire and crap thrown into the cab. |
| Scottacus:
I started by pulling out the transformer board and the metal enclosure for the game boards. I then carefully washed everything up with soap and water. There are scads of wiring harnesses and these were cleaned with a tooth brush while the rest of the cabinet was scrubbed and cleaned. Once everything was clean and dry I restarted the game and it worked just like it had before. I did this after every major act in the refurbishing just to be able to isolate any new problems. |
| Scottacus:
I checked the voltages on the linear power supply and they were all pretty close to the specs for the machine but a couple of the big caps had leaked and one of the diodes had burn marks at both terminals so I ordered a new cap kit from Bob Roberts along with a cap kit for the Wells Gardner 4600 series monitor as well as locks, leg levelers and some other parts. My primary concern was getting the joystick fixed so that the ship could move in all directions. The Gorf joystick uses flags to interrupt a signal from an IR LED and photo transistor to determine if the joystick has been moved. A voltage comparator determines if there has been a change in the voltage sent by the phototransistor and passes that information on to the game computer. Ithat the checked out the voltages and quickly found that the LED for the "move left" optocoupler was not working. This is what sent the signal to the board that was making the ship always drift to the left. Unfortunately the original part is no longer available so I did some digging and found that someone had used a Fairchild H21A1 optocoupler with good results so I ordered one of these. It was interesting to see that you could make the ship move to the right even though it drifted to the left. I take this to mean that the game strobed the joystick to check for right move before left, that was pretty lucky for me! I then took a look at the output from the voltage comparator and found that the set of pins that controlled the up motion never changed voltage while the LED and phototransistor both worked appropriately. This is why the ship wouldn't move up because the signal from the optocoupler never got past the voltage comparator. I was able to order a new LM339 so that was a pretty easy fix. Here is a photo of the joystick board, the optocouplers have the slits in them (CR1-4) and the bad LM339 is U1. Once the replacements came I removed the bad parts and soldered the new ones it. It worked like a charm, now my ship moves in all directions and the game suddenly got a lot easier. Watch out evil Gorfian Robots... |
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