The Machine Bride of Pinbot repair thread

[saint]

I have a BOP in fairly nice shape, was fully working for some time but has now developed some inevitable faults. Going to post about it in this thread and hopefully bask in the collective wisdom of resident pinheads. I've never worked on a pin before.

Known problems:

1. Dead right flipper. No response at all when button pressed.
2. Test mode reports a problem with 5 switches (one of which is the right flipper).
3. Various lamps out, no biggie though I'm thinking of LED replacements.
4. Second row of DMD is dead. No display at all. This is the one that concerns me.

So I'm hoping to dive into it this weekend. I've ordered a flipper rebuild kit for left and right flippers on general principle since they haven't been done in the 10 years I've owned the machine. I've also ordered a rubber set, and new pinballs.

General suggestions on where to start? I figured I'd start by looking for loose connections, reseat cables, etc.

[ChadTower]

Yeah, try reseating the appropriate cables, and it may "fix" the problem.  If that happens it means you should at least resolder the headers.  A better fix is replacing the headers and repinning the connector.  Jim and I have both said in the past that you always start with connectors in pinball.

Next I would go to those switches and check them.  Make sure they aren't broken or out of adjustment.  Test with the game in switch test mode with the ball.  Then with your finger.  Roll the ball over the armature and see if you can get it to register.  Using your finger will cause a lot of false positives as you will push the arm in further than the ball.  It's common for the microswitches to be worn out and connect if you finger push but not if you ball push.

If you can't get any registers on those switches check them in the switch matrix.  If they are all on the same row or column then go to the driver board and test the indicated transistor(s).  It could be more than one, so look for a matrix pattern in the dead switches.  That's how you figure out which transistor to test/swap.

The DMD one line out problem is often a cracked solder joint.  It might be on the video signal header, or a broken pin in that connector, or even on the DMD itself. 

[ChadTower]

Ah, yeah, I didn't check to see if that's alphanumeric.  The troubleshooting advice pretty much still holds in that if only one line is out you're looking at a connector or transistor issue.

[saint]

Thanks guys! That'll get me started this weekend

[Q*Bert_OP]

For the display problem, after checking connectors, look at the pins where they enter the glass. It's not uncommon for one or more to break from the glass. This can usually be fixed with conductive epoxy.

[saint]

I don't recall the display being out last time it was working (I know, duh), and the machine has been physically moved twice (a few feet each time, but still moved), so I'm hoping for a lost/broken connector.

[newkillergenius]

Well Saint, I know it's been a while since you've posted in this thread, but what was the outcome of the repairs on your BOP?

[sslakkerr]

Just wanted to say Thanks to you guys. Your info to saint got me on the right track to sort out some switch problems on BOP.

I lost a column of switches and I tracked it to the ULN2083 chip (that switch matrix in the manual is a great thing). I replaced the chip and the problem is fixed. If anyone does have to replace this chip, which apparently is known to fail, be warned that the solder rings on the board are extremely thin and will very easily poof into nothing. I had to run one jumper wire because of this.

I will be replacing two 39k resistors on the display board to hopefully resolve a weak lower display problem. I read that these tend to fail and cause problems with alphanumeric displays and it is a good first fix attempt. I'll post what comes of it.

Thanks again!