Gorf Speech

RetroHacker

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Well, I finally got a "round tuit" and started working on my Gorf. It's been sitting, awaiting resurrection - and today I decided to actually tackle it. It had a lot of issues when I got it:

http://forums.arcade-museum.com/showthread.php?t=90713&highlight=gorf+galactic

But now, I've got everything pretty much working. I replaced all the caps on the power supply (as well as two diodes), and got the voltages back to where they should be, and steady too. Disassembled the card cage and thoroughly cleaned the backplane, and all the card edge connectors. The game no longer locks up and resets, and I fixed the bad RAM.

The speech was always really weak - much softer than any of the other sound effects. I replaced some of the components on the audio board (two toasty 330 ohm resistors), and cleaned the pots. Both audio channels are working properly. But, the speech was still really quiet - almost impossible to hear. Originally, if you listened closely, you could hear it talk, and it was working fine. But now, now that I've got everything else working, the speech is no longer correct. All I get are a few random syllables - no words. Every time it's supposed to say something, I hear.. something - quietly - but just fragments and bits.

I have a "spare" boardset with issues (bad RAM card, bad pattern board, no speech), and I've tried swapping around boards, just for the heck of it. Swapped the CPU and the ROM board, no effect. I swapped in the other GAME board, but that one is clearly faulty - no speech at all with the spare board. Swapping the SC01 between the boards doesn't do much - the bad board produces no speech regardless of which chip it has, and the "good" board won't produce any speech with the SC01 from the bad board. So, the bad board has a bad SC01, as well as something else wrong with that circuit.

So, before I start digging deep into the sound circuits of Gorf, anyone have any pointers?

-Ian
 
Are both channels of the amp working? Those TIP31's go bad often. Replace with a 31C. Start a game and turn each pot up and down to make sure that channel is working. If they are both working I would suggest trying a known working SC01.
 
Yes. Both channels are working - I can independently turn down the sound effects for both channels.

I don't have any more parts on hand to swap, but if anyone has any, let me know.

-Ian
 
Most likely just a bad SC-01 they fail pretty often. I think coinopchips has some used ones in stock. Sometimes you can find them on eBay. GORF kinda sux with no speech. I had speach issues on mine and went all through that circuit chasing ghosts. When I finally got the replacement SC-01, I popped it in and success! the taunting began. I tried the headphone method but I just couldn't get it to work. (even with the new IC)
 
Well, it was just a bad SC01. I managed to get a known working one from a local pinball machine collector friend. The chip was also used in some Gottlieb pinball machines of the era.

Plugged in the new chip, and it's talking properly, and at the right volume too. So, my original chip was clearly faulty all along.

The speech does seem to have a bit of a "whistle" to it, that I don't remember Gorf having. But, it's talking, and that's what matters.

-Ian
 
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