So what's wrong with my Galaga?

irobot

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Picked up this Galaga today.

When I got it home, it worked with the coin door open. When I shut the door, itdidn't want to work any more.

Yet it worked at the arcade where I bought it with the door shut.

Screen is all green, obvious monitor problem.

Shows flashing pixels and so forth, makes rapid beeping sound.

Coin door wiring looks hacked, so does power supply.

The wiring for the free credit button and test switch is chopped off. Looks like a couple of fuses added to the power supply wiring.
 

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Have you tried the basic stuff like the wiring connectors on the board and reseating the chips on the board?

Check to see if you're getting the correct voltages to the boards too.

It's possible something worked loose while moving it, so whatever you do to get it playing may take care of the color problem.

-JM
 
Check all the wiring for shorts.

Check the +5v level at the PC board.

Reseat all the socketed chips

Clean the custom chips (repair any broken/rotted legs) and reinstall them.

These are all common problems on Galaga.

RJ
 
Check your voltage, i had a problem like that as well and it was my voltage.
 
Check all the wiring for shorts.

Check the +5v level at the PC board.

Reseat all the socketed chips

Clean the custom chips (repair any broken/rotted legs) and reinstall them.

These are all common problems on Galaga.

RJ

How do I check the voltages?

Also, how do I figure out how to rewire the stuff that was hacked?

Does the galaga share any parts with Ms. Pac man? I have one of those, I could compare them
 
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How do I check the voltages?

Also, how do I figure out how to rewire the stuff that was hacked?

Does the galaga share any parts with Ms. Pac man? I have one of those, I could compare them

You check voltages with a multimeter. You can buy one at your local Radio Shack. Get a digital one, not analog. Don't get the pocket or probe type either.

The manual for the game has the wiring diagrams in it. You can download it at http://www.crazykong.com

No, it doesn't share boards or power supplies with Pac Man.
 
Have you tried the basic stuff like the wiring connectors on the board and reseating the chips on the board?

Check to see if you're getting the correct voltages to the boards too.

It's possible something worked loose while moving it, so whatever you do to get it playing may take care of the color problem.

-JM

Does reseating chips mean removing and replacing into slot?

wiring connectors = clean connectors, correct?

Thanks
 
You have a board problem. It is most likely caused by dirty chip legs or a crappy chip socket. This is somewhat common when moving a Galaga from my experience. Re-seat the socketed chips as suggested by others above.
 
Check out the repair log on arcadeshop.com for Galaga http://www.arcadeshop.com/galaga/galaga.htm

About halfway down is a good example picture of dirty legs on chips, and how they should look clean. Right below it, shows the capacitor to check +5v on the cpu board.

Do you have the stock power supply, or a switcher? Stock power supply turns clockwise to increase voltage, and requires very little adjustment to raise it. The origional linear power supply can be source of issues, as some components are prone to failure. There are different wiring kits out there for replacing them with a switcher.
 
Does reseating chips mean removing and replacing into slot?

wiring connectors = clean connectors, correct?

Thanks

Yes, make sure the connectors fit well and that there's no corrosion on the board or wiring harness connections.

Be very careful when doing this with the chips. The legs are thin on the chips and you can easily make the situation worse by trying to force it (bending or breaking the legs off of the chip),

Someone has already linked to the Arcadeshop repair site for Galaga. Read it before doing anything else.

Also, if you find out you have power supply issues you can get the switching power supply and adapter that they (Arcadeshop) sell. It will be easier that trying to troubleshoot power supply issues and rebuilding the power brick and power supply. Cheaper too if you don't already own the tools for doing the repairs.

-JM
 
I would first try unplugging the connectors to the coin door and seeing if that makes a difference. I know I worked on a Galaga at Darryl's that worked just fine until I plugged in the coin door. After an hour of trying to track down why, I put tape over the connector with a message why and moved on to higher priority items on our list.
 
How do I check the voltages?

After seeing this, I would *NOT* recommend that you reseat chips on the Galaga board! Some of them can literally fall apart, even for someone who knows what they are doing.

Get someone experienced with Galaga PCBs to help with this part.

Sorry, not trying to scare you irobot, just want you to be aware that you can get in over your head pretty easily on this board set because of some inferior chip manufacturing.
 
After seeing this, I would *NOT* recommend that you reseat chips on the Galaga board! Some of them can literally fall apart, even for someone who knows what they are doing.

Get someone experienced with Galaga PCBs to help with this part.

Sorry, not trying to scare you irobot, just want you to be aware that you can get in over your head pretty easily on this board set because of some inferior chip manufacturing.

I have a degree in engneering and I have done some repair work already on games.

For example, I have replaced transistors in pinball machines and jury rigged burned PCB's to work properly.

Also, I've capped a number of monitors.

My knowledge base is fairly small, but I' very careful to do a proper job of things.

I have a multimeter and use it fairly often, but I would not know WHERE on the PCB to test the voltages and where the voltage adjustment pot is.


Stuff like that.
 
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I have a multimeter and use it fairly often, but I would not know WHERE on the PCB to test the voltages and where the voltage adjustment pot is.

I'm not sure what kind of power supply you have, but the adjustment pot (if there is one) should...well...stick out.

There are several places you want to check power: on the power supply itself, behind the harness, in front of the harness and on a chip on board. Here's why:

Checking on the power supply itself makes sure that it's actually working. In fact, as well as checking for DC voltages it's not a bad idea to check here for AC voltages as well. If there is any AC at all there's likely to be a problem with the power supply. Assuming there is to AC, note the DC voltage and move on to the next spot.

Next spot: behind the harness. Compare the voltage to the first voltage you noted. Is there a huge difference? By huge I mean more than 3/4 volt? There's a problem along the way, and you'll need to figure out what it is. There will /always/ be a drop, though how much depends on the harness and its condition. Could just mean reseating an intermediate harness - could mean a nearly broken wire. If that's okay, note that voltage and move on to the next spot...

Next spot: in front of the harness. Compare the voltage here to the voltage in back of the harness. Again, if there's a big difference, there's an issue. Likely oxidation on the pins of the harness. Take either a Pink Pearl eraser (yes, it makes a difference) or a fibreglass pencil and clean the edge connector. Also take a credit card and some very very fine grit sandpaper and buff the harness pins. Then reconnect and measure again. Obviously if the edge connector is burned it'll need to be repaired before you continue. Once you note that there is a very small difference in voltage, move on to...

Next spot: on-chip. This is one of the most critical spots for good voltage. Meter from the legs on diagonals at the ends. If you get an oddball voltage you've got the wrong pins - move to the other sides. Some boards will have a huge drop from where you measured in front of the harness, some will not.

As for where on your game you should be measuring voltages, consult the manual for where the ground and +5VDC go.
 
Finally a good answer.

I would first try unplugging the connectors to the coin door and seeing if that makes a difference. I know I worked on a Galaga at Darryl's that worked just fine until I plugged in the coin door. After an hour of trying to track down why, I put tape over the connector with a message why and moved on to higher priority items on our list.


Thats what I would do first. Could be shorting out the +5v circuit causing it to not power the board.
 
Thats what I would do first. Could be shorting out the +5v circuit causing it to not power the board.

He does have some sort of +5v going to the board. If he didn't, he wouldn't have the garbage screen since the clock circuit that the video circuit clocks are derived from is working. Whether or not it's the right voltage (4.95 to 5.2 volts) to make things work is another story.

RJ
 
There it is with the new Vision Pro monitor.

I took the motherboards out and cleaned the contacts. I think that fixed it. The contacts are quite worn.

Some of the chips have lightly corroded or repaired legs, I'll call arcadeshop and get new parts.

Also, I put on a new power cord. As you can see, the filter has a blue dot on it, indicating that it is polarized. The neutral connector on the old cord had a blue dot, so I plugged the neutral there on the new cord. But the old cord was so hacked up and taped together, I don't know if the blue dot side was really supposed to be neutral or not. Anybody know? Can you check on your machine.

Thanks for all the help so far.
 

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