Today's couple of drinks in project was to take WhoDunnit's old, failed slot reel stepper motor apart to see if it was recoverable for a spare.
The original symptoms were extreme heat when powered up (closer to 90°C!) and strong, crunchy mechanical resistance when manually turned without power. A stepper should move with very little resistance when there's no power to it.
The initial examination shows the bearings being just fine, but the rotors look shot. There's material missing and they're full of large metal shavings.
I look inside the chassis and the stators are in the same condition. Sorry, but this one's FUBAR.
Bad bearings would still be a recoverable condition, but even if the metal filings were removed, this one will never work right. The tolerance between the rotors and stators is very small and it seems even a small change ruins its behavior.
I wonder how this exact failure mode happens. Does the strong magnet in rotors first collect smaller metal debris, until it starts chopping away pieces from the stators until it seizes? Fortunately generic ones work in pinball machines just fine so it's a matter of wiring.
#pinball #repair #electronics
Ari [APz] Sovijärvi
npub1hz…xwwp4
2026-10-24 23:58:52 UTC
Author Public Key
npub1hzy4v5a5zxtc5xd6sse5hw3c7a3nt9ue37x42nl7skyfhe9jg0msyxwwp4Seen on
wss://relay.momostr.pinkPublished at
2026-10-24 23:58:52 UTCEvent JSON
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"content": "Today's couple of drinks in project was to take WhoDunnit's old, failed slot reel stepper motor apart to see if it was recoverable for a spare.\n\nThe original symptoms were extreme heat when powered up (closer to 90°C!) and strong, crunchy mechanical resistance when manually turned without power. A stepper should move with very little resistance when there's no power to it.\n\nThe initial examination shows the bearings being just fine, but the rotors look shot. There's material missing and they're full of large metal shavings.\n\nI look inside the chassis and the stators are in the same condition. Sorry, but this one's FUBAR.\n\nBad bearings would still be a recoverable condition, but even if the metal filings were removed, this one will never work right. The tolerance between the rotors and stators is very small and it seems even a small change ruins its behavior.\n\nI wonder how this exact failure mode happens. Does the strong magnet in rotors first collect smaller metal debris, until it starts chopping away pieces from the stators until it seizes? Fortunately generic ones work in pinball machines just fine so it's a matter of wiring.\n\n#pinball #repair #electronics\nhttps://some.apz.fi/system/media_attachments/files/117/498/591/687/687/792/original/f8e8cf5acbf48431.mp4\n",
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