saving a galaxy pinball

[ZZT]

Recently I buyed an old Stern Galaxy pinball in a very poor condition. Now I'll try to repair what is bad.


There is, cover with bird crap, dust, grapes (it was in a backyard from undeterminate time). I plug it in and no signs of live, except general ilumination. 

Next I try to open it and see what happend.

b.

[pinballwizard79]

ive played this one, cool game

[Paladin]

If you're lucky, the glass will have stopped any of that junk from getting to the playfield!  I'd love to see more pictures as you work on it.

[ZZT]

If you're lucky, the glass will have stopped any of that junk from getting to the playfield!  I'd love to see more pictures as you work on it.

Yes you right, I'm lucky!! Playfield is in pretty good condition (only a little heavy dust layer).
I opened the backbox to see the propper operation problem and looking at the MPU the diag led is stuck on, bad news. I check all the power supply volts and its ok. Now I have to see the MPU itself. 


I don't see any battery acid damage, so I think one or several chips are bad.

[ZZT]

Good news!
Today I fix the MPU! Finally I found several bad chips.
 
U5 and U6 proms. Both replaced with 2716 eprom
U7 RAM. Replaced with 6810
U9 CPU. Replaced with  6800
U17 burned out, replaced with a new 74LS00
U8 & U13 CmosRAM. Both replaced with L5101.

After several hours I finally recover the propper operation of the MPU.
At the beginning the led is stuck-on, then, using a oscilloscope I look at  the clock signal and determinate U15 & U16 are good, at least clock signal is good.
 
In the next step, I tested the CPU 6800 in another know-good Bally MPU and mark as bad. In the same way I test the PIA chips (both goods) and the RAM 6810, bad.

The next step are test the prom's. I read the four chips in an eprom burner and determinate U5 & U6 are bad. The propper code was burned in a old (but good) 2716 chips.

Whit this new chips replaced the diag led start to blink, but just give  only two blinks and still "on". Then I discovered that U17 (74LS00) are burned out, I replace it but whitout changes (just two blinks). Then I replace both CMOS U8 & U13 and BINGO, after all replacements the MPU led gives the 7 expected flashes.


Here is a fixed MPU. 
I never seen another MPU so bad like this, I feel very very lucky. 

[Mauzy]

WOW. I must say, I'm impressed! That's a lot of crap to sift through. Kudos and congrats!

[Kevin Mullins]

No kidding...... I only wish I could get to that level of diagnostics.
Still learning, but that addressing an clock stuff would have thrown me for sure.

Well done !!   

Looking forward to further progress.

[ZZT]

No kidding...... I only wish I could get to that level of diagnostics.
Still learning, but that addressing an clock stuff would have thrown me for sure.

Well done !!   

Looking forward to further progress.

The clock signal is the first thing we have to check. Without that the MPU never start. It's not so dificult to learn, but an osciloscope or logic probe is needed.


After repair the MPU I fix some dusty switch's and bad lamp sockets.


Me, cleaning the playfield.


Shine, like brand new! 


Ready to play.


I playing. 

[Mauzy]

No kidding...... I only wish I could get to that level of diagnostics.
Still learning, but that addressing an clock stuff would have thrown me for sure.

Well done !!   

Looking forward to further progress.

The clock signal is the first thing we have to check. Without that the MPU never start. It's not so dificult to learn, but an osciloscope or logical probe is needed.

The right tools can definitely make any job easier! That play field looks great, btw.

[Kevin Mullins]

Well, I have a cheap logic probe....... every now and again I'll break it out and poke around with it and watch all the pretty lights and listen to the beeps and buzzes.
 

Now if I could just learn how to use it. 

I enjoy seeing pins of this era come back to life. Something about them puts you into the game a bit more than the newer stuff. (in my opinion of course) Something deeper about the gameplay and sounds I guess.

[ChadTower]

Very nice.  I'm still working up to using my oscilloscope too. 

[ZZT]

Well, the machine works so nice that I decide go one step forward and restore the (cabinet, backbox, coin door and legs) I mean a complete restoration. My process to copy the cabinet design is a little handy but more cheap than commercial stencils. Besides I don't have the money to buy them. 




The first thing I do is take a picture of the design.



Sand paper to remove the old paint and scratches.



Spread body filler and a lot (very lot) of sand paper.


This process is similar to car body fixing.

We'll continue.... (paint). 
 

[ifkz]

clip that old battery from the MPU before it leaks!!!!

[ZZT]

clip that old battery from the MPU before it leaks!!!!

I keep in mind!!!!

New photos. Three days of intense work.


Black.


Stencil.


Yellow.

Tomorrow, red.

[ZZT]

Almost ready.

[ChadTower]

Nice! 

 

[ZZT]

Done!

[cptnwhlz]

congrats! looks great