Help! Gorf giving me a black screen

[8 1/2]

I've been looking to sell my Gorf cab, and I turned it on and it looked ok. Voices were all static though. Text was fine, as was title screen, but as the game began it only displayed half the enemy ships and half of the player's ship. I took out the ram/rom board and pulled each socketed chip, cleaned and replaced them. Now I get nothing but a black screen.

Any help?

I have a spare board, but i don't know where to start replacing chips, and the spare board gives me a black screen as well.

[8 1/2]

Oh, also on the main dip-switch board (that connects to the cables) I tried to replace the SC-01 chip from my spare but to no avail.

[8 1/2]

Also on the ram/rom board there is a chip in socket x33 that looks like a fuse or something? It has little metal bands that run across where the pins are located. A few of those strands are broken. What is that chip for? Is that a fuse?

[fuko]

Can you play the game blind? Is there any audio at all, suggesting it's a problem with the display?

Can you post a pic of this mystery chip?

Might want to also post this at the klov help forums. Lots of old timer knowledge on the classics over there.

http://forums.klov.com/ubbthreads/postl ... d=KLOVHELP

[8 1/2]

I swapped over all of what I assume are the logic chips (each one was labeled as Gorf A through Gorf H).Now I have it back to half-sprites and no voices. Sound effects are fine, but voice is gone.

Here is the "fuse" in question in the upper left of the photo. It appears to have some small bands that are broken.

[fuko]

I am no expert, but that doesn't look like a fuse to me. Looks more like a 'hard' dip switch

A fuse would have one bridge on it that is meant to break when amperage exceeds a threshold, while this chip has many bridges.

[8 1/2]

ah, ok. That makes sense. Some of the bands do look hand punched.

[8 1/2]

Update: I replaced the logic chips, but that doesn't seem to be the fix.

Lately, the voices play very, very softly (barely audible) and there is a lot of static. The sound effects (shots, explosions) play fine, and at full volume.

Also, the text scroll at the attract screen looks fine, but the title is missing the right half of each letter in GORF. During gameplay, the same is true for the player's ship and the enemy ships. Game logic seems to be intact as I can play the game, even though it only renders half the sprites.

I have a backup set of boards, but they're not complete so I can't just do a full swap. I'm trying to figure out which rom controls voices and the right half of the sprites. Can anyone point me in the right direction?

[fuko]

The problem with classics like Gorf is that they were pre-jamma and didn't follow any standard architecture which would simplify troubleshooting. Logic is often spread out over a number of boards that are unique to the game, and your problem could be caused by any one of a number of components.

Case in point: the speech in Gorf wasn't sampled and stored in ROM at all, but is generated on the fly by a speech synthesizer chip (SC-01, later machines may have had SC-01-A, according to wikipedia).

Start with running through the in-game diagnostic. There is a manual here (warning, 37MB) that explains the procedure and how to identify a bad ROM (if that is your problem)
http://basementarcade.com/arcade/librar ... g/gorf.pdf

I would personally also be inspecting the power supply/transformation/regulation boards, looking for whatever is providing sound amplification to the speech synthesizer. Many, many problems that manifest as unexplained graphics or sound glitches tend to originate here as capacitors start to go bad over time.

Finally, be sure to post over at KLOV, as the ppl there have years of experience, and chances are someone there has seen this exact same problem. Might save you a lot of time looking for the proverbial needle.

I hope you are able to save another classic from the landfill. Good luck!