Stern LOTR: Help, I Somehow Killed an Entire Switch Column

(Topic ID: 207237)

Stern LOTR: Help, I Somehow Killed an Entire Switch Column


9 months ago

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  • 8 posts
  • 3 Pinsiders participating
  • Latest reply 9 months ago by DANGERTERROR
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#1 9 months ago

My right slingshot was misfiring so I began to fiddle with the switch blade spacing. While doing that, the switch died completely -- along with the entire GRN-GRY column (lanes and slings). I yanked the diode out and tested it, and it was indeed bad, so I thought I'd found the issue. I reflowed the solder on the switch and added a new diode and ... no change. The column is still dead.

So: I have a few more wire continuity tests to do (game is on location and I'll be back this weekend) but I have a bad feeling this is a board issue. Could a bad diode or some other sort of under PF issue knock out a switch column?

And: I saw that upstream from the column connector are transistors (confused by that), is that likely the component that's bad? I do have a donor board I can mess with.

I did a bunch of searching and couldn't find any Stern switch matrix problems/solutions like this. Any advice on testing or potential board issues is welcome.

IMG_5285 (resized).jpg

#2 9 months ago

If you think it might be a board problem disconnect the playfield and test the switch matrix with jumpers. If it's still bad it's a board problem.

#3 9 months ago

If you verify if this is a board problem,you will need an o'scope or logic probe to troubleshoot further, but most likely you blew Q8 and replacing it should fix the problem.

#4 9 months ago

For the jumper test, would I simply “close” the switch on each pin by jumping the GRN-GRY column to each switch row pin?

I think a have a transistor year I can do on Q8 after that.

Thanks for the ideas so far!

#6 9 months ago

It’s pictured but not explained: but basic enough. No diode needed, you jumper the row and column pins in Switch test mode. I can do this. Will report back.

#7 9 months ago

Pin test confirmed column is dead on the board. No switches activate when jumped from pin 9. Replacing Q8 — still worried something under the pf can blow it again. Or maybe it was bad from the start? Yikes.

#8 9 months ago

Replaced Q8 and all is good.

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