Stargate appears to constantly reboot?

BullWeivel

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Having a problem with a Stargate machine.

On one of the boards with an LED readout it states 1 than 3 than 3. Sometimes it reads 1 than 3 than 4.

Screenshot attached of what the screen does.

Any idea on what might be causing this?
 

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Could be a couple of things:

1) Reseat all connectors.
2) Check ribbon cables
3) Reseat RAM chips.

I would do all three then turn it on and see what happens.

There is also the chance that your power supply is a problem. Check the voltages it's putting out.
 
Yes, I have a multimeter. :)

Just wondering how to know what the voltages should be ?

I dont have a manual on this or anything so.
 
I have the same prob

I picked up a HUO stargate for $100 and it has code 138. Comes up to colorfull snow then wipes accross to mostly black screen. and plays a few of the stargate sounds over and over. Is the 138 code indiacting a bad rom in that position possibly? Attached is a pic of the HUO (no pics+didnt happen) No burn on the monitor and in really nice condition.
 

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The manual has the direction on how to read the LED display. It is usually a row and column. My manual is 7 hours east, if this hasn't been answered by Saturday, I'll be home and I'll dig it out.

The first thing you should check before ANYTHING is the power. Low power will flag ram errors. If you replace the ram, you'll either get the same error, or the error will move. The manual tells you what the test points are, and better yet, Stargate has LEDs on the power board, where you can see if the "idiot light" thinks the power is good or not.

The last time I had ram errors, it was the PS. I bought a rebuild kit from Bob Roberts, and it works fine. The first time, I lost a RAM chip. I have around 10 4116s in stock, so I just swapped it out.
 
Well, I got stuck on this, so I looked up the manual on this site.

The code means:
1: Ram Error
# = Which bank (left to right)
# = Which RAM Chip (top to bottom)

It's on Page 2 of the manual, page 4 of the PDF.

If the code is 2 - it's a ROM error.

So, 1 - 3 - 3
is:
Ram Error, Bank 3, Chip 3.

The move between 3 and 4 indicates a power supply issue.

1 - 3 - 8
Ram Error, Bank 3, bottom chip.

Huzzah. It could STILL be the power supply. Power up, and look at the LEDs on your power board. If any are off after a minute, power down, and either rebuild the board, or install a switcher.

Generally, if you install a switcher, you'll lose your coin mech lighting. Generally.
 
Huzzah. It could STILL be the power supply. Power up, and look at the LEDs on your power board. If any are off after a minute, power down, and either rebuild the board, or install a switcher.

Generally, if you install a switcher, you'll lose your coin mech lighting. Generally.

Voltages can be measures on the 4 corners of any of the RAM chips. THe voltages should be -5, +12, +5 and ground. If any of these are low, rebuild your power supply board.

If you install a switcher, leave the power supply boards in place and leave the small connection that goes to the coin door on the side of the PS board. Then you will still have ground and the coin door switches and lights will work.

Note: I do not recommend putting a switcher in any game that uses a 6809 CPU (or any 680x CPU) but particularly not the Williams games. When the voltage drops below about 4V on a 680x series processor, it writes to memory at random. If the write occurs in the space where the CMOS is, you will looks your settings and/or high scores. The Williams power supplies compensate for this with that big capacitor. It acts like a battery keeping the CPU voltage up until the memory protect circuit senses the 12V dropping. With switchers the +5V and +12V drop off at the same rate and there is plenty of time for the CPU to hammer the CMOS RAM.

You are always better off rebuilding the power supply, rather than putting a switcher in.

ken
 
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