Galaga Driving me nuts!

JoeB1355

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I've been working on the this Galaga board on / off for 6 month or so. About a week ago I finally made some progress and got the video board working.

New RAM and Customs. I tested a bunch of customs that didn't disintegrate on a dig dug board i had that worked. solder pins etc.

All 2114's were bad (I bet someone put them in upside down!)

I checked all ROMS (burnt a couple new ones) and CPUs.


I checked all the sockets

CPU doesn't have the ceramic resistor packs

I have another Galaga board I tested the video on that worked

I tested the bad CPU on the good video -- so its definitely the CPU board


So I started with dead white screen I now have something that kinda boots and says it ok, but no cross hatch then reboots in a cycle forever.

Has anyone see the pattern in this video that could help?

Video: http://youtu.be/tAHzBaDE8-o

Anyone got an idea of where to go next? It looks to me like its not kicking over to the next CPU or something like that. The CPU's are good though and sockets looked and ohmed out from CPU pins to backside.

PS -- this was a junkboard that someone had already swapped bits etc and left for dead -- so quite likely there are multiple problems (I already found a couple!)
 
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Check the 2nd and 3rd CPUs. They aren't starting.

The CPUs, EPROMs connected to them, 8xx chips, or the R/W line has issues.
 
Ahhh... Galaga boards... I have a stack here I have to start going through, not looking forward it. And since I added nothing constructive...
Its-driving-me-nuts.jpg
 
Someone on here was selling a Galaga PCB rebuild kit, it was a very complex but complete kit. Do a search and it should come up, if that doesn't work pm me and i'll pull the kit. I haven't used it and it will have the sellers name on the package.
 
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Check the 2nd and 3rd CPUs. They aren't starting.

The CPUs, EPROMs connected to them, 8xx chips, or the R/W line has issues.

Thanks -- gotta go outta town for a few days -- I dig into that when I get back

Is there a reset / handoff signal / line or something from the first CPU that supposed to kick the second?

Is there a theory of operations floating around on the inet? I haven't been able to find one.
 
The 2nd and 3rd CPU reset lines are tied together. The first CPU takes the 2nd and 3rd CPUs out of reset when it finishes its self test routines.

At that time the 2nd and 3rd CPUs start to run and must trigger a watchdog reset circuit by running properly. If they don't, the watchdog circuit kicks in and resets the whole boardset and the cycle starts again.

And thanks for the pr0pz guys... the Galaga renew kit is something I built and sell. It's not for beginners and not for the faint of heart.

RJ
 
Someone on here was selling a Galaga PCB rebuild kit, it was a very complex but complete kit. Do a search and it should come up, if that doesn't work pm me and i'll pull the kit. I haven't used it and it will have the sellers name on the package.

It was Chuck Fitch.




Sorry Ray, had to go there.
 
The 2nd and 3rd CPU reset lines are tied together. The first CPU takes the 2nd and 3rd CPUs out of reset when it finishes its self test routines.

At that time the 2nd and 3rd CPUs start to run and must trigger a watchdog reset circuit by running properly. If they don't, the watchdog circuit kicks in and resets the whole boardset and the cycle starts again.

And thanks for the pr0pz guys... the Galaga renew kit is something I built and sell. It's not for beginners and not for the faint of heart.

RJ

Ok I probed line 26 on 2nd and 3rd cpus looks like it getting the signal. its nevre really goes low though its start at abaout 1.7 volts and when its gets signal its looks like data streaming -- but that what iots looks like on CPU 1 all the time.

I pull both 2nd and 3rd cpu off to see what happen and it stop at the RAM OK solid black screen with either removed.

so I think all 3 cpus do start --

I probed WDR and didn't see it go high -- so that means its not resetting right?

nothing seems too hot except the 2 proms which get super hot although I did swap them with the good board it didn't fix it so not an issue?

its hard to follow signals. I probed pin 7 on 3C reset not -- but it never changed yet pin 26 on the CPU's did

Is this the same signal?
 
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