saving a galaxy pinball

[ZZT]

I buy an old Galaxy (Stern) pinball in a very poor condition. Now i put hands on the job of restore the operation of everything i can.


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

Next i try to open it and see what happend.

bye

[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!! the playfield is pretty good (only a little heavy dust layer).
I open the backbox to find the propper operation problem and i see the led (on the MPU) is stuck, that is bad news. I check all the power supply and is in good condition, all volts are OK. Now i see the MPU it self. 


I dont see any battery acid damage, so i think the problem is one chip.

[ZZT]

Today i repair the MPU. 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 (exploited) 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, then using a oscilloscope I see the clock signal and determinate U15 & U16 are good, at least clock signal is good.
 
The next step is test the CPU 6800 in another know-good Bally MPU and determinate is bad. In the same way I test the PIA chips (both goods) and test the RAM 6810 (bad too).

The next step is 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) two 2716 chips.

With this new chips replaced the led give me only two blinks and still "on". Then I see U17 exploited, I replace it but no changes obtained. 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 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 paint all (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.


Paint in black.


Stencil.


Yellow.

Tomorrow paint in red.

[ZZT]

Almost ready.

[ChadTower]

Nice! 

 

[ZZT]

Done!

[cptnwhlz]

congrats! looks great