Galaga...No Missles

Joe351

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Hey All:
Been here for 2 years, first time I've needed help.
Have had a Galaga for almost ten years. No problems.
All of a sudden...no missles and no kills!
Still makes the missle sound when pressing fire, so the fire button works.
Picture and sound are perfect.
No freezes or reboots.
Voltage is good.
Cleaned edge connector.
Cleaned and reseated most of the rams & roms.
Cleaned connector on rapid fire board.
Swapped the connector from rapid to slow fire position.
Had a ver 4.4 e-pack and removed it to fix this problem.
Does anyone know which rom is associated with the missle generation or function?
If I knew that perhaps it might be a broken trace associated with that chip.
I have a few donor boards I can swap chips with.

Thanks for any help!
 
I would look at the custom chips, they get really black tarnished legs on these boards, and stop making good contact after awhile. You have to carefully remove them (the legs will break if you're not very, very careful), clean them, and reinstall.

I can't stress enough though that you have to be very careful with the legs. They'll break if you look at them wrong, and the chips are about 20 bucks each to replace.
 
Thanks for the quick reply!!

I already tried cleaning chips.
Didnt change anything.
I will try it again.
Tried swapping a few chips with donor boards.

Wondering what I am missing.
Anyone know what chips are associated with the missle function?

Thanks again
 
Cleaned and reinstalled chips again.

Same deal. No Missles.

Any other suggestions?

Not sure what to try next.
Any other ideas?

Thanks
 
I don't think this will work but have you tried to reset the high score table?

worth a shot.

Huh?

There is no saved high score table on Galaga.

Are the spaceships normal or are they missing lines/have vertical stripes?
 
What is this?

Had a ver 4.4 e-pack and removed it to fix this problem.

I thought this was for the rapid fire and high score table.

Sorry about that....
 
Thanks for the suggestions.
I will try anything you suggest at this point.

E-Pack did save high score.

I have had the PCB out about 20 times trying to fix this, and
everything comes up now in original format with no high saves.

E-Pack is removed.

Channelmaniac--- No lines...video is perfect.
Sound is perfect.
I get the missle fire sound when pressing FIRE.
No Missles.......cant kill anything.
Fighter moves.
Characters drop missles that still kill me.

One little clue today.

With the connector on the slow(single fire) set of connectors
on the fire choice pcb I get the fire sound but no missles.

On the rapid fire connector I get no sound OR missles.

The slow fire option connectors are just jumpers and I
checked them from the pins to about 3 inches into the wires to make sure the
rapid fire pcb and connectors were good.
Connectors are clean and good.

Thanks to all for help and ANY suggestions!
 
I don't really know what chip(s) control the missles so hopefully somebody who does will chime in. I would follow the fire button backwards and see where that goes. The is probably a single line that is not toggling correctly to do this, this can be caused by a number of issues. A feed through that doesn't, a bent leg, faulty ttl chip.

Check pins 11 and 3 of the u2 chip on the rapid fire board. It is a nan gate and should go low when the fire button is pressed. The inputs are 12 and 13 for 11 output and 1 and 2 for 3 output. I think you will find that the problem is after this but we can go from there.

Also does your board have the flat resistor packs?

I think there is a "match flag" and that will do the "kill"

something like missle location and bad guy = show kill.

Thanks for the suggestions.
I will try anything you suggest at this point.

E-Pack did save high score.

I have had the PCB out about 20 times trying to fix this, and
everything comes up now in original format with no high saves.

E-Pack is removed.

Channelmaniac--- No lines...video is perfect.
Sound is perfect.
I get the missle fire sound when pressing FIRE.
No Missles.......cant kill anything.
Fighter moves.
Characters drop missles that still kill me.

One little clue today.

With the connector on the slow(single fire) set of connectors
on the fire choice pcb I get the fire sound but no missles.

On the rapid fire connector I get no sound OR missles.

The slow fire option connectors are just jumpers and I
checked them from the pins to about 3 inches into the wires to make sure the
rapid fire pcb and connectors were good.
Connectors are clean and good.

Thanks to all for help and ANY suggestions!
 
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I like the "trace fire button backwards" suggestion.
I was assuming the wires to/from the rapid fire pcb are
ones to trace back too.

Some of your suggestions are a little over my head but I will try
and let you know how far I get.

Thanks for the suggestions!!!
 
Correct me if I am wrong, but if I am on the single(slow) fire pins, the rapid fire board cant be the problem because the slow fire pins are only jumpers and do not
function through the rapid fire board components.
I got a PM that the 3N rom is the firing chip.
Can anyone confirm this?

Thanks again.
 
Correct me if I am wrong, but if I am on the single(slow) fire pins, the rapid fire board cant be the problem because the slow fire pins are only jumpers and do not
function through the rapid fire board components.
I got a PM that the 3N rom is the firing chip.
Can anyone confirm this?

Thanks again.

The rapid fire board is where the fire signal goes through so it could be a bad jumper or a jumper that has some resistance; yes it could be anything where there is a connection. Like a wire it must all connect. However, I don't think that is your problem. You get sound when the fire button is pressed so the button is probably working and the jumpers through the board.

There is some rom hacks for the game and I don't know how many different roms there are for 3j but I think I have 3 of them.

I think you will find your problem is a connection with a chip; rom or custom. I don't think your edge connector could be the problem. The ribbon cable is a weak part too so you might try to crimp it in a vise.

I know there is a way to de compile the roms and look to see what is supposed to be going on but I don't know how just yet. Maybe ask DarenF. There should be something else going on when fire sound is on and that is not happening. The custom 51xx does the inputs and outputs but I am not sure that it does the missile.

The pins on the customs are very frail and much care is needed here but you might try cleaning the 51xx chips and see if that changes anything.

EDIT:

I re read your post about changing the connector< slow fire=+sound -missiles|< Rapid fire= -sound -missiles

I would first look at the connections and not just the ribbon cable. Look at the pins that connects to and look at the solder job of the pins. look for any debris that could short a pin. Look for any bent/loose pins. I just fixed a power supply where the pins going to the output had worked loose from the solder pads. If you wiggle the pins slightly and see it moving on the solder side; it needs to be re flowed
 
Last edited:
I know there is a way to de compile the roms and look to see what is supposed to be going on but I don't know how just yet. Maybe ask DarenF. There should be something else going on when fire sound is on and that is not happening. The custom 51xx does the inputs and outputs but I am not sure that it does the missile.
The roms can be disassembled (not decompiled, they weren't compiled in the first place). However, the code will mean absolutely NOTHING to you unless you are familiar with the Z80 instruction set, and the Galaga hardware.
 
OK, I am getting nowhere with getting missles to fire.
Still wondering if anyone thinks I should try swapping the 3N chip
with a parts board I have.

Meantime, out of frustration, I bought another board.
It has this smaller board attached.
Anyone know what this is?
 

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  • Galaga Board 1.JPG
    Galaga Board 1.JPG
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Small board is an EMI filter board - you can keep it on or toss it aside - All indications are that they just introduce another point of failure to the board connections.
 
You might have a tin whisker issue. Take a close look between the legs of the chips that are in the firing circuit.

These things are developing over time. The small whiskers flash off when they make contact. If you get a big one, you can get it to cause a ground and drop out.

You can read up on these little buggers on the NASA website.

http://nepp.nasa.gov/whisker/background/index.htm
 
OK...

Installed another PCB boardset and the game is running perfect and solid as ever.
Swapped video board and game plays fine.
So the problem is definately on the CPU PCB.
The socketed chips have been removed and cleaned twice.

I have heard of a rapid fire EPROM chip(not the E-Pack deal)
Where would that be installed?
Would it be a logical assumption that this is the missle chip??

I am detirmined to get this fixed.

Any suggestions now that I know prob is on main board???

BTW Thanks for all the help.
 
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