Stargate Restart Problem / Interface Board

cpyne

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Hi,

I have a Stargate that will restart roughly every 30 seconds if the interface board is plugged into the CPU board. If I don't plug it in, the machine stays up and running fine. When it is hooked up , it actually does function and you can move the ship up, down, etc, but a restart happens before you get play very long.

When I bought this machine, the guy did warn me the interface board was bad. Apparently he had two Stargates and his other one developed this problem. He pulled the good working board from my machine and installed it in his to get it working so he could sell it. I ended up with his "Fixer" Stargate.

Does anyone have any ideas what could be wrong with this interface board? I tried swapping the 6821 PIA on it since I had an extra lying around, but that didn't help.

Charlie
 
First thing I would actually check is the power supply voltages, at the power supply AND on the main board and interface board.
I've seen this exact scenario and all it was was the voltage dropping just a hair. (5v supply if I recall correctly)
 
You should probably try re-crimping the connector. The wires get loose and stop making connections after a while. Also check the resistor packs (the bright orange long skinny things on the top of the board). They can get hairline cracks and start causing problems. If you find one or both are cracked, you can get replacements at Jameco.

ken
 
Here are the voltages I see...

Power supply pin out - 4.98 V
CPU Board connector in - 4.87 V
CPU Connector out - 4.76 V
Interface board traces - 4.64 V

Does that sound good/bad?

I checked the resistor packs on the board, but I didn't see any cracks.

I'll give the re-crimp a try later when I have a spare moment.
 
THANK YOU! I just re-crimped the ribbon cable about 1/8" further up the cable and now it seems to be working great!!!!
 
Just curious, but what are your voltages looking like now after the recrimp ?
(namely on the interface board for sure)

Oh, and glad you're up and running strong now.
 
The voltages are all pretty much the same except for the interface board which is now showing 4.78V
 
The voltages are all pretty much the same except for the interface board which is now showing 4.78V

so by way of tidying up the explanation, 74lsxxx series components have a typical requirement of a minimum positive supply voltage of 4.75 volts, therefore a positive supply voltage of 4.64 volts for the IO board means the 74LS257 ics will not perform as expected. :001_ssad:

but you've fixed it so :)
 
so by way of tidying up the explanation, 74lsxxx series components have a typical requirement of a minimum positive supply voltage of 4.75 volts, therefore a positive supply voltage of 4.64 volts for the IO board means the 74LS257 ics will not perform as expected. :001_ssad:

but you've fixed it so :)

Hey, that's good info to know.

So...basically, his Stargate is running "on the cusp" as it were. Anyway to get that a bit better, other than cranking up the juice?
 
Hey, that's good info to know.

So...basically, his Stargate is running "on the cusp" as it were. Anyway to get that a bit better, other than cranking up the juice?

as in the prior posts, fixing this issue can be done by a number of methods:
1. check the power supply output - if around 4.9-5.1 thats good as it allows for some losses through cables/connectors (always check at the outer pcbs) and check voltages on your power supply aree as per the schematics. the 5v line on the defender style pcbs cab be made adjustab le - have a look back at dockerts defender replies or yellowdogs and you'll find reference to that mod (done it myself)
2. cleaning pins & contacts in pcb headers and wiring plugs/sockets, resoldering headers pins (if dry or cold solder joints), checking the crimp connectors used in wiring looms connectors/pins/sockets and replacing faulty ones or re-crimping, for ribbon cable connectors betweens pcbs re-crimping or pushing the wires further into the little v displacement connectors in the connector body (or fitting a new one), make sure all earth leads.straps screws etc are clean and have good contact everywhere

they're the main issues that i've gleaned so far from many and various, particularly dokerts and yellodogs (among others) responses on williams games/power supplies issues!

cheers!
Andy
 
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