GOTG's Groot was having bit of a spooky issue. His jaw motor was disabled in the game, but much to our surprise it started moving on its own during the attraction mode and game play, eventually trapping balls inside when it shouldn't move.
Diagnosing it I made an interesting discovery: the issue stops when I enter the diagnostics menu and resumes during the attraction mode. The diagnostics also refuses to drive the motor as it's disabled in the software.
What causes it to move? After looking at it a while, I notice the movement starts when more playfield lights light up on the right side of the playfield, then I spot odd flicker in some LED boards.
This platform drives the LEDs and this motor board with SPI bus and it's daisy-chained. One board or its wiring going bad will also take the downstream boards with it. This is what happened here too. I found a bad connector, that was causing some noise in the bus and apparently the commands got distorted to address the motor board instead of the lamp board.
I pulled the board with a bad connector and found cold solder in its connector pins. Some soldering later the issue is gone, for now.
#pinball #electronics #repair #arcade
Ari [APz] Sovijärvi
npub1hz…xwwp4
2026-06-13 20:34:23 UTC
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npub1hzy4v5a5zxtc5xd6sse5hw3c7a3nt9ue37x42nl7skyfhe9jg0msyxwwp4Seen on
wss://relay.momostr.pinkPublished at
2026-06-13 20:34:23 UTCEvent JSON
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"content": "GOTG's Groot was having bit of a spooky issue. His jaw motor was disabled in the game, but much to our surprise it started moving on its own during the attraction mode and game play, eventually trapping balls inside when it shouldn't move.\n\nDiagnosing it I made an interesting discovery: the issue stops when I enter the diagnostics menu and resumes during the attraction mode. The diagnostics also refuses to drive the motor as it's disabled in the software.\n\nWhat causes it to move? After looking at it a while, I notice the movement starts when more playfield lights light up on the right side of the playfield, then I spot odd flicker in some LED boards.\n\nThis platform drives the LEDs and this motor board with SPI bus and it's daisy-chained. One board or its wiring going bad will also take the downstream boards with it. This is what happened here too. I found a bad connector, that was causing some noise in the bus and apparently the commands got distorted to address the motor board instead of the lamp board.\n\nI pulled the board with a bad connector and found cold solder in its connector pins. Some soldering later the issue is gone, for now.\n\n#pinball #electronics #repair #arcade\nhttps://some.apz.fi/system/media_attachments/files/116/744/702/248/744/203/original/ce498526d68f1b77.mp4\n",
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