Stargate fixed!

I got lucky this weekend and was able to get the Stargate game working. After I pulled the game boards out of the cabinet I verified that the mode of failure was the same, nothing on the screen, no sound, and bizarre display on the 7-segment display that posts error messages.

The values being posted kind of looked like '1..3..1..' which is a RAM failure. Since I happened to have an extra set of 4116's I swapped them all (one back at a time) and nothing changed. I then read on on these types of failures and the CMOS RAM was a suspect. So I cut out the 5114, put in a 18-pin socket and stuffed a 2114 in it's place. That would be functional but it wouldn't allow for battery backup, but I didn't have a 5114 laying about. Of course this didn't change anything.

I then found some Stargate troubleshooting documents, one in particular stood out (here), and the emphasis was to check the power first before doing any other work. The first step is to check that the regulated voltages coming off the power board are proper, the second step is to verify that the voltages at key points throughout the system are proper.

Sure enough there was no +12 (regulated) coming out. With my scope I could see I had good voltage at the test point, but the connector going off-board had only about 1.92v. I pulled the small daughter card and could read a good voltage without the connector, leading to me to suspect something was pulling down the +12. Once I reconnected everything I got a good reading on the +12v going off board, and Stargate booted! The important lesson here is that one should always check the voltages first.

At some point I'd like to do a "get well kit" on the power board, but everything is working and this isn't a priority.

Now that Stargate is working I have to choose my next game to fix, Battlezone or Missile Command. Battlezone is such a physically large game that the current plan is to disassemble it to get it from the garage into my basement work area. Another project I have is to get a 15v2000 (15" black&white vector) working. This has been sitting on the shelf for the last 10 years (!!) and really needs to get fixed - though I don't have a game to hook up to it. My original plan was to use this with my Zektor ZVG in bar cabinet, but I'm kind of hooked on a 19" screen for the ZVG.

Wrapping up Defender

Since I purchased the Stargate game, the priority has been to get Defender done. I decided not to refinish the cabinet at this time, but electronically the Defender game is done. I ordered some feet from Happs Controls (leveler feet) to replace the worn ones on the game, and now Defender is back to being upright.

My preliminary testing of the Stargate game indicates the monitor is fine, so the problem (the game just shows a blank screen, no sound) is with the game boards. Looking at the power supply the LEDs are all lit, so it appears that the power supply is good as well (I’ll put a probe on it to make sure).

So now Defender is back in it's cabinet and playable. I need to tighten up the joystick, it's a bit sloppy, but otherwise the game is in good condition.

I have pulled all the electronics out of Stargate. Tomorrow I'll hook them back up and start the process of figuring out what is wrong. I've ordered a battery backup kit (the lithium battery one that Bob Roberts sells), and some RAMs just in case.