(Topic ID: 161900)

Slugfest mpu not working properly

By Wharhed

7 years ago


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  • 12 posts
  • 3 Pinsiders participating
  • Latest reply 7 years ago by Wharhed
  • Topic is favorited by 2 Pinsiders

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#1 7 years ago

I recently picked up a slugfest that was running/working, except the bat wouldn't swing when you pressed the button. The price was right, so I scooped it up and brought it home, figuring I was going to find alkaline damage; Slugfest did not disappoint.

I found that there was light damage, and the batteries were actually oozing. I cut off the battery holder, neutralized the base, scrubbed the affected area and flushed with rubbing alcohol.

White there was a few darkened traces, I found only one trace that was actually eaten up. I replaced all the corroded parts and jumpered the broken trace.

When I finally hooked everything back up, I'm greeted by garbage on the dmd, the bat moves when I press the button and a single bong sound.. not much else. The mpu's activity light is blinking like it should. If I cut power for the cab a half second, and turn it back on, I get the bong, and attract lights. The bat no longer works at this point. The dmd still has garbage and none of the coin door buttons work, doesn't coin up, etc.

I haven't really worked on these newer mpu's too much, and wasn't quite sure where to start. Any tips?

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#2 7 years ago

What are the LEDs on the MPU doing?
You might have corrosion under J206.
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#3 7 years ago

The led's are following the pattern that was defined as "normal"; One stays on (+5v) and the other is rapidly flashing (denoting CPU activity).

Thanks for the info, all the connectors on the bottom seemed to be unscathed, but I'll pull J206 and see if any corrosion made it under there too.

#4 7 years ago

Not sure where else to go with this. I've verified that there is activity all over the board and all the columns are toggling like it's doing stuff.

For all intensive purposes, the mpu acts like it's running properly. I've tested the ribbon cables extensively, and tried unplugging one board at a time. No changes. On initial power up, GI kicks on and the dmd has garbage on it. Single bong from the sound board.. No other visual activity.

If I disrupt power for a half second, a ball or two is kicked out, and attract mode displayed. The dmd still has garbage. Buttons inside the coin door do nothing.

I haven't found any broken traces, and I've toned out just about everything.

Any help is appreciated

#5 7 years ago

Looks like you have corrosion under J206 and J208 as well as some other resistors and diodes above J206 and J208. You also need to check and replace the .100" female connectors that are damaged like I show holding in the picture.

Slugfest_MPU_alkaline_damaged_(resized).pngSlugfest_MPU_alkaline_damaged_(resized).png
acid_damaged_connectors_(resized).jpgacid_damaged_connectors_(resized).jpg

#6 7 years ago

Can you please post a picture of the MPU after all the new parts were installed?
It is best to lightly sand on the solder pads after removing the damaged parts. Applying heat to an alkaline damaged pad, heats it up fast and totally disappears. It is best to apply heat to the bottom side of the board only (at least until the top side is lightly sanded and then neutralized with vinegar and finally cleaned with alcohol).

#7 7 years ago

For the display issue, can you follow both ribbon cables at the top of the MPU board and reseat the connectors at all the board connections? Think you may have one of the ribbon cables one row off.

#8 7 years ago

Can you post a picture of the boards with the game turned on? Hoping to see if you have either the 12 volt F115 fuse blown (test TP3) or the unregulated 12 volt F116 fuse blown (test TP1).

#9 7 years ago

I appreciate the info, however I believe I ended up resolving the issue. I pulled U16 (which didn't have any signs of corrosion on it), and found that the traces for pins 3 & 12 were dead under the chip. I put in new machine sockets and jumpered the damaged traces. Slugfest now runs and plays correctly, minus the dmd.

At this point, I'm going to guess that the dmd driver board has failed. I have a working JM that I'll pull the dmd driver board from and try it tomorrow.

As for the J20X connectors, I had already replaced the cabinet side IDC connectors and pulled headers from the board - no corrosion was found.

Thanks again for the help and troubleshooting steps, I do appreciate it . I just wish I would've pulled that chip sooner.

#10 7 years ago
Quoted from PinballManiac40:

Can you please post a picture of the MPU after all the new parts were installed?
It is best to lightly sand on the solder pads after removing the damaged parts. Applying heat to an alkaline damaged pad, heats it up fast and totally disappears. It is best to apply heat to the bottom side of the board only (at least until the top side is lightly sanded and then neutralized with vinegar and finally cleaned with alcohol).

That's excellent info - I was only neutralizing the base, rinsing with alcohol, using a fiberglass pen on the pads, and then rinsing with alcohol again. I'll have to do that next time (hopefully there's not a next time )

#11 7 years ago
Quoted from Wharhed:

As for the J20X connectors, I had already replaced the cabinet side IDC connectors and pulled headers from the board - no corrosion was found.

Did you replace the Male header pins on J206 and J208? You did not reference them in your response. I can see there are some corrosion on some of these male pins. All the white residue on just above the J206 connector is alkaline damage that did indeed hit even hit many of the parts above J206 and J208, which look like dull solder. You will have to take care of this soon as well.

Slugfest_MPU_alkaline_damaged_(resized).pngSlugfest_MPU_alkaline_damaged_(resized).png

#12 7 years ago

Sorry - yes, this picture was before I cleaned up the mpu. I originally didn't replace them, but I went ahead and did it when I pulled them after the first reply.

When I pulled them, I neutralized, and rinsed with alcohol. They were super clean underneath though

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