Stargate: Fluctuating Volume

Cliff Clavin

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Argggghhhhh, I just get my donkey kong fixed and another game starts acting up....

heres the scoop on the stargate....

I have a stargate running with a switcher. The game was working fine (other than a refusal to recognize a coin up so I had it running on free play) but now every so often the volume goes up dramatically....scared my kids first time it happened. (well it scared me too actually)..

I have the volume pot turned all the way down and the volume is at a reasonable level, a little loud but tolerable.....however every so often it decides to go very loud and scare anyone within 20 feet....

Does this sound like a volume pot that is simply buggered? If so, does anyone have the specs on a replacement pot?? Anything else I should look for??


Thanks all.....
 
The pot is where I would start.

Have you 'wiped' the pot several times to the left and right?

Do you have another Williams game that would allow you to simply swap the pot and wires/connector to the sound card?
 
Thanks fellas. Will investigate as soon as I can get some free time with no ankle biters around.

Had a few minutes so decided to play with the pot....turned it back and forth a few times and tried to give it a "pot workout"....so far so good, volume is consistent....I found an old volume pot from my robotron I think which I may solder in if I am still having issues....though this replacement pot doesn't look so good either....
 
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I finally received a new replacement pot for the stargate....While the pot does not adjust the volume as far down as I would like, hopefully it will prevent the fluctuating volume issue. So far so good but I really have not yet had a chance to properly test it out....

If this doesn't work, I have a robotron sound board I can play with.....
 
For future references (in case anybody searches and finds this thread) Williams uses 1/4 watt 5K audio taper pots for the volume control.

ken
 
For future references (in case anybody searches and finds this thread) Williams uses 1/4 watt 5K audio taper pots for the volume control.

ken

Ken,

Thanks for the specs on the volume pot. Hopefully it will help others along the way...I was placing an order at mikesarcade and noticed and then decided to order these pots

http://www.mikesarcade.com/cgi-bin/store.pl?sku=POT10KMATSU

So far it seems to be working ok...I have it turned to its lowest setting and the volume is just right for me....Not sure if the issue is resolved but I will followup as needed....There is nothing worse than tech threads that are not followed up on....
 
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Well the loud volume reared its ugly head again.

I stopped into a local electronics supply store and the closest pot they gave me is a 5k ohm 2W .....rather than the 1/4 W that Ken says is required.

Now the volume is very quiet, too quiet and does not adjust at all using the 2W pot......Arrgggghhhhhhh......anyone?
 
Watts shouldn't cause that

The watt rating is the disapation rating - it's the resistance that changes the volume. You basically bought a more robust potentiometer than you needed.

Check your connections again. Something isn't right - try metering from the pin to the leg (bypass the solder connection) and look for a cold joint.

This isn't "sounding" like a bad potentiometer issue to me. You may have a bad resistor on the sound board - something loose or getting cooked off (although I haven't seen resistors go "variable" that doesn't mean it can't happen). A cold solder joint and temperature changes could cause this behavior.
 
I was feeling ambitious last night and decided to have another go at the stargate. Perhaps ambitious is a bit strong as I was too lazy to move the cabinets so I just went through the coin door....of course in hindsight, it would have been easier to move the cabinet.

Anyway, the volume was now really very low, almost silent....I tried my robotron pot and it did not make any difference so as arcade tech postulated, perhaps the problem lies elsewhere.

I fooled around pressing the volume molex connector and suddenly, the volume was there but quickly went quiet again...

I decided to swap in my robotron sound board to see if it helps...Unfortunately, no sound at all with the robotron board....arrrgghhhhh....

Decided to swap back in the stargate board after re-seating the sound rom chip and voila....it works again...the pot works and the sound is back to adjustable levels......not sure how long this will last but a guess is that maybe I have a flaky solder connection or some loose wiring in the molex connectors...frustrating but for the time being all is well.....
 
Rom socket? Hmmm that could explain why reseating the chip caused it to start working properly again. Are the sockets known to suffer from corrosion over time?
 
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