Need stargate help!!!!

jpk0652

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Just put a new switching power supply in a stargate. Now for some reason the thing wont credit up and you cant put it in test mode either. Its almost like the game wont reckognize that a coin door is there. I checked and there is no power on the door no where either. It was working before I put the new power supply in. Has anyone out there had this problem??? Any help is greatly appreciated. Thanks
 
Just put a new switching power supply in a stargate. Now for some reason the thing wont credit up and you cant put it in test mode either. Its almost like the game wont reckognize that a coin door is there. I checked and there is no power on the door no where either. It was working before I put the new power supply in. Has anyone out there had this problem??? Any help is greatly appreciated. Thanks

Your coin door is probably missing the ground... the ground to the coin door comes from the small header on the old power supply board... not the main 15 pin harness.
 
O.K how do I reground it??

If you removed your old power supply then:

You need to connect a ground wire (from your switcher) to pin 6 of the wire harness that used to connect to the power supply board.

If you still have your old power supply board in there:

Keep that 6 pin header connected to it and make sure the power supply board ground is connected to the switcher ground.

Schematic/wiring:
http://www.robotron-2084.co.uk/manuals/stargate/stargate_upright_drawing_set.pdf

Other info pertaining to switchers in Williams games:
http://therealbobroberts.net/wmslamps.html
 
As retroActive said, the power connector for the coin door supplies the ground as well as the 6.3VAC to run the lights and the coin lockout solenoids.

There are other problems with running a switcher in a Williams cabinet thet you should be aware of. Due to the design of the 6809 CPU, when it is powering down, the CPU will randomly write to the memory address space. If that is a ROM or dynamic RAM address, no big deal. The ROM will ignore it and the RAM will be reinitialized the next time anyway. But if that memory address is in the CMOS, you can lose your high scores or the settings. The Williams original power supply was designed to minimize this risk by having that large capacitor on the power supply board. This keeps the power to the CPU on for a few extra milliseconds, which is long enough for the CMOS protection circuit to detect that the 12VDC has gone down and to turn off the CMOS chip enable. This protects the CMOS from shutdown writes by the CPU. You lose that protection when you replace the original board with a switcher.

Is there some reason you went with a switcher? There are a couple of us on the board that rebuild Williams power supplies or if it is missing, we can sell you a rebuilt one for very reasonable prices. PM me for details.

ken

I just hate to see people drop switchers in and then wonder why they are losing their scores or setting all the time.

ken
 
And to think... Frizz just asked why putting a switcher in a Williams is a bad idea. Seems like we keep beating this dead horse again and again.
 
As retroActive said, the power connector for the coin door supplies the ground as well as the 6.3VAC to run the lights and the coin lockout solenoids.

There are other problems with running a switcher in a Williams cabinet thet you should be aware of. Due to the design of the 6809 CPU, when it is powering down, the CPU will randomly write to the memory address space. If that is a ROM or dynamic RAM address, no big deal. The ROM will ignore it and the RAM will be reinitialized the next time anyway. But if that memory address is in the CMOS, you can lose your high scores or the settings. The Williams original power supply was designed to minimize this risk by having that large capacitor on the power supply board. This keeps the power to the CPU on for a few extra milliseconds, which is long enough for the CMOS protection circuit to detect that the 12VDC has gone down and to turn off the CMOS chip enable. This protects the CMOS from shutdown writes by the CPU. You lose that protection when you replace the original board with a switcher.

Is there some reason you went with a switcher? There are a couple of us on the board that rebuild Williams power supplies or if it is missing, we can sell you a rebuilt one for very reasonable prices. PM me for details.

ken

I just hate to see people drop switchers in and then wonder why they are losing their scores or setting all the time.

ken

Is this the 5 volt that has the large capacitor? Can you just put a large capacitor to the same voltage line coming out of the switcher and get the same result? If so what would the capacitor size need to be?
 
And to think... Frizz just asked why putting a switcher in a Williams is a bad idea. Seems like we keep beating this dead horse again and again.

Is this the 5 volt that has the large capacitor? Can you just put a large capacitor to the same voltage line coming out of the switcher and get the same result? If so what would the capacitor size need to be?

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Two dead horses for the price of one ....

The answer to the actual question, is yes you can, but....

a) You need a capacitor with a value over 10,000uF,
b) for most switchers, you need a current limiting resistor to prevent the capacitor from tripping the current protection circuit in the switcher.
c) when you do this, you risk of damaging the CPU board while the capacitor is charging, unless
d) you put a secondary 5V regulator on the CPU board side of the new circuit.

At which time you have just built a linear power supply fed by the switcher.

So you can either swap back to a linear power supply, or just get used to your CMOS getting trashed periodically. Who know, you might get lucky and it may work fine. Or you can be like most of us and have it happen about once a month.

ken
 
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