Gorf Audio issue $%$%@$

skramarck

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Gorf has been my problem child since I got it...never had a game that is this finicky...

Anyway, Was having some intermittent lock ups, so I figured I would check all connections, reseat the boards, etc. Did this, game came back up, worked wonderfully, no more lock ups....BUT....

I have lost the audio on Channel 1.....I have no voice sounds or missile firing sounds. I just have all of the other sounds on both speakers. Did a check of all known fuses, voltages, etc....no dice.

Swapped out transistors, resistors, potentiometers from channel 1 to channel 2 and vice versa (did this one pair of items at a time). The problem never moved from one channel to the other. Checked the speaker wiring, everything looks good there.

Reseated everything, checked connections again, and fired it back up. For about 20 seconds, I had very faint voice and missile sounds then it went away.

I have no idea what else to check. I would be open to purchasing a known working stereo audio board to see if something that I didn't check in the board is fried (and to have a spare), but where else might I look? Since I didn't lose just the voice, I don't think it is the voice chip but I'm not sure.

Any help or guidance is much appreciated.
 
Voltages at game board are -5.06 12.05 and 5.08

I must admit that I am not sure how to properly check voltages on the audio board.

I did not swap out CR 1 and CR 2, going to try that now and that leaves only one part untouched....will look at that too but I assume that if that part was bad I would lose all audio?
 
Audio is controlled by the two custom input/output/audio chips on the "game board". This is the board, in the 6-board stack, with the connector header pins. These two custom chips are identical. They are the only two 40-pin chips on this paticular board. Try (carefully) reseating them. You could also swap the two(with each other), and see if a different problem appears (different audio missing, or certain controls not working). This could help narrow the problem down to one of these custon chips.

Edward
 
thanks for the tips....I will swap out the chips and see if that moves the issue. All pins look ok, but I will look closer. If I am reading the schematic correctly, pins 1-3 of the 28 pin connector carry audio. I noticed those pins had been bent a bit, but the still seem to be ok. Will try to check continuity there.

One good thing about Gorf being such a PITA..I am learning a lot about video games!

Will report back.... I really miss Gorf taunting me!
 
One good thing about Gorf being such a PITA..I am learning a lot about video games!
The good thing about having almost any project snowball is that you'll come out of it with a lot more knowledge and experience (if you persevere to the end, of course :D). These games are not much more than digital logic 101, so with some poking and schematic reading you can figure out almost anything.

LeChuck
 
Just to provide some closure for anyone using the search function to track down Gorf issues. My audio issues were multi fold. Initially, I think I had a bad connection at the audio board which ultimately caused on of the TIP 31s to fry. In the time period while I was investigating this, I lost some caps on the original power supply. This of course caused me to lose my -5, +5, and +12 voltages. I was still able to play the game, just with no sound. Upon repairing the PS with the rebuild kit from Bob Roberts, I noticed that while I had my voltages back, I still had no sound or test functions. Another look found a blown fuse in the three fuse array at the transformer (although it blew in such a way that it was not easily visible). A quick trip to Rat Shack and the fuse was replaced and as of tonight, Gorf is taunting me again!

Along the way, I secured another audio board from Monster Kong which is also now completely functional. I pretty much need only a functional game board set and a wiring harness to have just about all pieces of this game in duplicate.

I've never learned so much about a game or gotten so frustrated along the way as I have with this Gorf, but long live the Gorfian Empire!

thanks to all who provided guidance along the way!
 
Glad you got the audio back, and thanks for posting all the things you had to do. Knowing others will benefit from your work makes it nice, but hearing 'nice shot, space cadet' makes it better.
 
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