(Topic ID: 113297)

IJ4: Spinner triggers Trough Jam, ends ball

By jfesler

4 years ago

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  • 7 posts
  • 2 Pinsiders participating
  • Latest reply 4 years ago by jfesler
  • Topic is favorited by 1 Pinsider


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#1 4 years ago

We have an IJ4 that once in a while, shooting an orbit, triggers end of ball. Flippers stop working, ball drops to the trough, and curses fly.

Digging more into it, we found that the right orbit spinner [06] is also_ triggering the indicator for trough jam [22]. Both share the white-blue return line.

Triggering the optical trough jam sensor does not trigger anything else. Triggering the right orbit top [38] and bottom [54] also trigger nothing extra.

Disclaimer: I'm new here. But, in my mind, it seemed like perhaps focusing on the spinner [06] was in order. Disconnected it under the play field, then tested the diode with a multimeter. The diode check function reported near-0 values in both directions; whereas known good diodes were reporting 0.6 volt drops in one direction and no flow in the other. "Ah ha!"

Alas: swapping the diode for a fresh 1N4004 appeared to have no effect. I also confirmed that the orientation of the diode matched the original position, as well as matching the other microswitches on the field.

I'm reaching the limit of my n00bness, looking for advice. Am I misunderstanding the likely culprit in the switch matrix? Should I swap the opto board out on the trough jam [22]?

Below is the matrix for IJ4, with the two sensors highlighted where I'm seeing my problem.

#3 4 years ago

Found this, seems useful.

"Troubleshooting Pinball Switch Matrix with a Shorted Diode" by PinballRehab

Looking at the video, looking at the switch edge test.. I think this means check all positions in the trough (18 through 21). I'll give those a shot once xmas is over.

IMG_0559.JPG IMG_0560.JPG
#4 4 years ago

All diodes replaced on the trough; still no joy. Only thing left, if I understand the video .. is swapping the opto receiver.

#5 4 years ago

Tested new opto transmitter and receiver loose: works.
Installed new receiver: fails again.
Test new transmitter and old receiver loose: works.
Installed original opto receiver, only barely screwed in: works.
Tighten lower screw: works
Tighten middle screw: fails again.

Basically, with the middle screw in more than finger (no tool) tight, things work fine. Any tighter, and the right orbit spinner [06] triggers the trough jam [22].


Physically inspecting the board, and everything nearby when attaching the board, we see absolutely no way anything can be shorting out; but obviously something is happening. And it happens with both old opto and new opto. Whisky Tango Foxtrot!

At least the game is now playing fully correctly.

#6 4 years ago


I would look carefully at the traces on the PCB for a crack. Sounds like it might be a case of the PCB flexing when you tighten the screw causing a cracked trace to open. Get a nice bright light and magnifying glass and take a close look. Let us know how things work out.


#7 4 years ago

I'll do that. Would you expect a new opto board to have the same behavior?

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