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(Topic ID: 224510)

Advice needed - Gottlieb System 80 MPU


By tman67234

2 years ago



Topic Stats

  • 10 posts
  • 4 Pinsiders participating
  • Latest reply 2 years ago by G-P-E
  • No one calls this topic a favorite

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There have been 9 images uploaded to this topic. (View topic image gallery).

back a1j4 (resized).jpg
front a1j4 (resized).jpg
j1 (resized).jpg
power (resized).jpg
hot2 (resized).jpg
hot (resized).jpg
back (resized).jpg
front (resized).jpg
bat damage (resized).jpg

#1 2 years ago

Hi,

I recently picked up a Force II machine. This is my first pinball project. I have a fair amount of past experience involving electronics and soldering. The game does not boot. I'm currently sorting out my various power issues. But in the interim, I'm interested in some system80 gurus' advice on what to do with my MPU. Here's the front and back of the board:
front (resized).jpg
back (resized).jpg

For starters, the MPU<->DriverBoard was soldered together. The bottom of the cabinet contained the original connector (with broken pins), so I'm planning rebuild it and clean up the solder from the boards.

Someone previously removed the battery, however there is some damage that needs to be addressed:
bat damage (resized).jpg
What all needs to be replaced? I was thinking of doing the 2 ICs, 3 resistors, and the crystal. Do the traces need some sort of work typically?

Next, some components looked like they got hot at one point, see below. Is it something I should be concerned with?
hot (resized).jpg
hot2 (resized).jpg

Additionally in the photo above, someone soldered in some jumpers connecting PROM1 to PROM2 and drilled out some traces. Note: the jumpers do not follow the original traces. I'm pretty confused on this and what the purpose was, especially considering PROM2 is empty.

Lastly, the power connector (A1J2) is rough. The copper pad is loose and flaky. Is this something that can be fixed?
power (resized).jpg

Is this board worth fixing? Or should I be considering getting a replacement?
Any and all advice or suggestions are appreciated!
Thanks

#2 2 years ago

Fixable but may take a bit of time. You may need to go a little higher in parts replacing. For example - R45 has corrosion as well.
Hard to tell if there is corrosion under items such as Z1 or the DIP switch without pulling them.

Start with a good cleaning and go from there. Make sure to clean off any alkali that crept under the solder mask - particularly near Z1 and Z2 (you may need to replace both depending on what it looks like under Z1).
But remember - those DIP switches don't like water. Even if they are "dried" or blown out - there is always a bit of moisture left over in them. Over time, they develop a nice blue-green layer of corrosion and stop working.

Somebody replaced U6 (without installing a socket). Looks like they may have damaged thru-holes resulting in the three extra wires.

U13 has also been replaced. The repair person didn't clean up the flux resulting in what looks to be a heated spot on the bottom of the board. Clean that up with alcohol and it'll look just like the other joints.

See here for more info:
https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Battery_Leakage_and_Corrosion

#3 2 years ago

First and foremost, thanks for the response GPE!

Quoted from G-P-E:

Somebody replaced U6 (without installing a socket). Looks like they may have damaged thru-holes resulting in the three extra wires.

U6 does look different on the front of the board, so makes sense that it has been replaced. However, those 3 wires are on PROM1 and PROM2 (not U6). Any idea what they could be for? Really suspicious since some traces are drilled out as well.

Quoted from G-P-E:

U13 has also been replaced. The repair person didn't clean up the flux resulting in what looks to be a heated spot on the bottom of the board. Clean that up with alcohol and it'll look just like the other joints.

I believe that is Z12 and the alcohol worked great. Good call!

Lastly, what are your thoughts on the main power conntector (A1J1). Any way to repair the flaking pad?

#4 2 years ago

If you actually want to get this up and running any time soon shell out the money for a Rottendog. I didn't see any pics of the driver board but he sells a nice one to. An added benefit is either will dethunk your game. You can recoup some of your losses by selling the old ones on eBay. Good luck to ya' TH

#5 2 years ago

Oh yeah, The jumper wires on the back along with the cut traces are just to make an old System 80 CPU run one prom games. Or newer software.

#6 2 years ago
Quoted from tman67234:

U6 does look different on the front of the board, so makes sense that it has been replaced. However, those 3 wires are on PROM1 and PROM2 (not U6). Any idea what they could be for? Really suspicious since some traces are drilled out as well.

I believe that is Z12 and the alcohol worked great. Good call!
Lastly, what are your thoughts on the main power connector (A1J1). Any way to repair the flaking pad?

Yep, that's what happens when you flip a board and see the mirror image - your eyeballs follow the traces to the wrong place...
They changed the ROMs resulting in the wiring changes.

The J1 connector seems to only have a corner missing on the 2nd pin. The plug contact on that pin may be reaching in far enough to still hit the remaining pad. Unless the copper is lifting from the board, it seems to mainly need a good cleaning and re-tinning. To do a complete repair, you need copper tape and practice. not sure you need to go to that extreme yet.

But at this point, I think it's too soon to go with the replacement board method.

#7 2 years ago

As you said it is your first pinball project, even with your experience involving electronics and soldering it looks like you will have to spend some hours (days?) of work. If it is to learn more about 'Gottlieb technics' and you are able to spend the time, go for it.
Otherwise you may think about replacing the MPU with LISY80
www.lisy80.com

#8 2 years ago
Quoted from bontango:

If it is to learn more about 'Gottlieb technics' and you are able to spend the time, go for it.

The impatient side of me is quick to want to replace the MPU. But ultimately, there is no rush and I'm going to try repair first and learn some things along the way. I had not seen the LISY80 project. I already have 3 RPis running things in my home (8 chime MIDI doorbell, 3d printer, and garagedoor), so the thought of controlling the pinball with a RPi (and/or Arduino) did cross my mind if all else failed. So it's really awesome to see the project in existence! But yea, for now, going to try and repair.

Quoted from G-P-E:

The J1 connector seems to only have a corner missing on the 2nd pin. The plug contact on that pin may be reaching in far enough to still hit the remaining pad. Unless the copper is lifting from the board, it seems to mainly need a good cleaning and re-tinning.

No worries about the mixed up parts! I greatly appreciate the help. Only corrected for clarity and my own sanity.
As for the J1 connector. Here is a closer pic:
j1 (resized).jpg

I very gently raised the copper pad for visibility. It is still attached. Is there a fix? Can it be glued back down? If so, what type of glue? I have some CA glue from RC stuff laying around.

As for re-tinning. I know the exposed copper is no-good and will corrode. I assume more than just my power connector needs to be re-tinned? How do you tell? Is it as simple as, if you see the copper, than it needs to be re-tinned? When I go to re-tin, do I use generic solder? Or is there some special solder to be used?

Thanks for all the help thus far!

#9 2 years ago

Just fixed up A1J4 that had the directly soldered wires. De-soldered the wire first, fluxed + solder wick the excess solder, and then lint-free alcohol cleaning. The front cleaned up very nicely:
front a1j4 (resized).jpg

The back almost did, however, some of the pads lifted (just like that power pad):
back a1j4 (resized).jpg

Now I'm very interested in hearing how to address lifted/loose pads. Haha. After doing this, re-tinning makes more sense.

#10 2 years ago

There's a couple vids on youtube for this -- such as this one:

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