Garbled Galaga

ColoFan

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Has anybody ever seen a screen like that on a Galaga pcb, and know what might be wrong?
In an attempt to fix, I cleaned the pcb and inspected a lot of pins and connectors visually and with ohm meter. I cannot see anything wrong.
Also, no sound.
Any advice anyone ? Thanks.
 

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Has anybody ever seen a screen like that on a Galaga pcb, and know what might be wrong?
In an attempt to fix, I cleaned the pcb and inspected a lot of pins and connectors visually and with ohm meter. I cannot see anything wrong.
Also, no sound.
Any advice anyone ? Thanks.
is it animated or static? is it in a boot loop?

Galaga isn't a very user friendly game for the inexperienced to work on. I know what I'm doing and have fixed some over the years but it's not something I consider myself to be great at working on. lol

half of the battle is going to be the Namco custom chips (the solid black chips with numbers in the corner) because their metals will corrode black (which is the easier part) or if they've been sitting corroding for a very long time, the metals become brittle and break off (which means you need to create donor legs). another issue is the resistor packs, if they're the flat wafer looking variety, they're fragile and can break. the sockets can go bad too, I discourage going kitchen sink fix and replacing every single one of them because Bally/Midway boards are pretty fragile to solder on. thus, there's more layers than Shrek with these.

@channelmanic is the expert on these but I don't know if he's taking any on to fix cause he's very busy. I don't even think he has the Galaga refresh kits in stock.
 
Yes, dynamic moving squares for a while, then almost white screen and restarts the cycle like a boot sequence.
 
probably not what's wrong, but verify this Freeze dipswitch isn't set to on. you might get lucky and that's all that's wrong.

galagdipswitch.png
 
Thank you for your time, I appreciate the help! I've always wondered what that switch is for. The manual says for dip switch 6J, sw#5: ON: FREEZE VIDEO (MONITOR PRESENTATION ON
STOPS MOVING). OFF: MONITOR OPERATES NORMALLY... weird
I checked and mine is off...
1751218764118.png
I did try to switch it on for giggles, and get pretty much the same dynamic gabled screen.
 
That's the self test going... If it's restarting look closely at the screen for an error message to flash by momentarily.

I'm OOS on the rebuild kits only because I'm low on one of the parts for it and need the stock to do repairs. Now that VCF Southwest is done and in the books as of a week ago, I'm back to doing repairs and projects.
 
I made some progress. Cleaning and resetting the z80 chips got rid of the watchdog problem. It no longer reboots, it fairly quickly stops on this screen.
I'm worried about doing more harm by soldering all these small resistor arrays.
Should I try anything else first?
 

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Nobody going to tell him to check power supply? just start pulling chips? could of had a simple issue now it looks like he's screwed
 
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Yep, checked power supply and voltages. I also swapped another working Galaga board that works in that cab. So, I'm now focusing on bad contacts on the PCB... but I don't want to go crazy on the poor old board either.
 
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When I got my Galaga home, the first thing I did was clean the edge connector AND plug with Electronics Cleaner. It rectified the fuzzy screen I was getting.

However, mine, too, has no sound. I'll post a seperate thread about the sound issue.
 
When I got my Galaga home, the first thing I did was clean the edge connector AND plug with Electronics Cleaner. It rectified the fuzzy screen I was getting.

However, mine, too, has no sound. I'll post a seperate thread about the sound issue.
well the sound section has to work for the game to work, so it has to be something in the amplification circuitry or maybe have a bad speaker/bad connection. do you get amp pop and a faint buzzing? the amp works and so does speaker/wiring. if nothing at all I would ohm the speaker, should be 8 ohm I believe. I'm certain there's an op amp somewhere, I've never needed to replace one and my Galaga fu is weak, cause both of the ones at work are working.
 
well the sound section has to work for the game to work, so it has to be something in the amplification circuitry or maybe have a bad speaker/bad connection. do you get amp pop and a faint buzzing? the amp works and so does speaker/wiring. if nothing at all I would ohm the speaker, should be 8 ohm I believe. I'm certain there's an op amp somewhere, I've never needed to replace one and my Galaga fu is weak, cause both of the ones at work are working.
For a moment, I was thinking a bad LM324. But, reading your post, it may be something else. This thing was caked with dust, everywhere! It might even be a dirty connection. I'll scope it out. Thanks for the pointers!
 
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