Galaga issues

ManiN

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Galaga has a glitch where it will work and then constantly make the coin up noise for about 20 sec. then quit with the coin noise leaving the controls inoperable during and after the 'coin attack'. Haven't checked my switcher voltage yet. Any prefered 5V level it should be at?

Also, there is a speaker buzz that is horribly annoying. Someone said it may be from the switcher I put in, but I have other games with switchers, and none have a speaker buzz. Is a line filter bad maybe? I was jiggling the edge connector and seemed to get better, but after cleaning it still buzzed without the intermittent, so that made me realize it was just cutting out completely, not just eliminating buzz. Unplugging the marquee light didn't make a difference either.

Thanks!
 
Recap the audio section and see if that takes care of the buzz.

As for other issues... Galaga suffers from a few common things: bad sockets, tarnished/corroded chip legs, and poorly made resistor packs. These cause lots of weird issues with almost every aspect of the game.

Clean the legs on the custom chips on both boards and see if the issues go away.
 
I didn't even think of pulling chips. I bet you're right. This machine is very original, however, that also means nothing has been touched. I've had to replace the power supply, rebuild the monitor, now mess with the board. All very worth it, but during the process, I could see surface oxidation on all contacts etc., so I have a feeling you're probably right.

I'll have to look at those caps on the sound circuit. I hope it's that simple.
 
If you are very confident in your desoldering and soldering capabilities, I sell a kit on my website that contains all new 24/28/40/42 pin sockets and resistor packs that makes Galaga a LOT more reliable.

Installation is NOT for the faint of heart. Instructions are on the downloads page of my site.

RJ
 
Yeah, I'm decent for a hobbiest on soldering and desoldering. I use a bulb that seems to work, but is definetly a learned skill of timing and accuracy haha. I'll take a look at the board, and if it's in need, I'll hit you up.

Would using desoldering braid be easier in this case?
 
NONONONONO!

Braid is never OK on a board with fragile traces like Galaga.
 
Well, I pulled chips and polished the legs last night. Many were black with corrosion! I put it back together and soldered a few broken legs on some resistor packs (not for the faint of heart ;) ). After that the glitch seems to be gone. I didn't test it for hours on end, but did fire it up and jiggle things which seemed to piss it off before.

The buzz is still there, however, I've yet to investigate the capacitors.
 
Still no reaccurance of the glitch! :)

Re-capped the sound section with no change. I found some other threads that suggest filter issues. I bypassed the original power supply to put in a switcher, and noticed the audio is routed through the power supply in the schematics. Is there a filter circuit in the original PS I eliminated by bypassing it?
 
If its got the crappy fragile type resistor packs I would replace them. Channelmanic sells a kit, saves alot of hassle searching for the right ones since I doubt you can find them all from one source.
You have to be real careful with the traces on galaga. They lift easy and are real close to one another so its easy to short them when resoldering. Recheck all your work before firing it up. If your not real experienced in desoldering/soldering I would suggest retesting after each part you replace. This way if you run into an issue you will know where the problem is.
 
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