Stargate Interface Board Repair

[jasonsmith]

So the past few days I've been working on Stargate. I've cleaned up a few issues and am onto the Interface board. In the switch test mode no switches test okay, I get nothing. When I'm in the game settings the select cursor just scrolls down on it's own as if I'm joysticking down. I disconnected the control panel with no change. Disconnected the connectors at the interface board with no change. I took out my interface board and it's very corroded on a couple of the MC14049 chip legs. I tried to resolder them but I think the pads on the bottom of the PCB are corroded away, the solder is sticking to nothing.

So... anyone know where I should start. Looking for a PCB repair guide or something I guess.

If anyone has a spare interface board for a Stargate, Defender, Robo etc that would be cool as well.

[jasonsmith]

Okay guys thought I'd just chime in and let you know that Stargate is fixed.

There were two issues. The first being something on the Interface board. Don't know what as I did the shotgun approach and replaced all the chips and the cap. They were all replaced with their latest and greatest equivalents so hopefully it'll last longer this time. If I had to guess I'd say it was 6821 chip.

I still had some issues with the controls activating when they shouldn't so wiggled the ribbon cable and it seemed like the 20pin Main PCB header was the issue. Took out the PCB and took a look and it was cold solder joint galore. Removed all the solder and re-soldered the header and it's perfect now. While I was there I did the Lithium battery mod.

The ribbon cable was fine along with its two connectors.

[iankellogg]

if i had to guess what the issue was, its probably an input buffer and you would have replaced that when you shot gunned it.

[jasonsmith]

That's interesting. I did have a lot of corrosion around one of the buffers, at least I think it was buffer... 4049?

[iankellogg]

4049 is a buffer chip.

[the_real_mcp]

Ribbon cables and header connections fail *very* often on williams games, esp if original ones.
-Changed loads...

Now I replace them every time with IDE cables for PCs, etc. :-)

One occasion a 6821 was faulty, replaced, socketed - sorted.


BTW, do a 4164 Ram conversion on the cpu board so it runs cooler, Dave Langley's site has this documented well.
4116's just get waaaaay to hot (due to +12V needed)...


Cheers,
Dave.

[jasonsmith]

Thanks Dave, I'll look into the conversion.

Right now I'm having a different issue with my 1G IC. It's a Octal Bus Transceiver that's heating up and failing. If I hit it with cold spray the issues go away, if I let it heat up the game crashes. I've changed it out once but found my ROM board ribbon cable was bad after I swapped it. I think it may have been the reason with the issue but not sure. Could my bad ribbon cable wreck that IC or what else could be causing it to heat up.


https://www.dropbox.com/s/5w3r0w9wkharih3/Screenshot%20from%202014-05-22%2013%3A06%3A40s.jpg