Field guide
Top-Bottom Joint
How it works
A classic two-part mechanical device used against older electromechanical slot machines. A wire inserted through the bottom hopper and a bent rod through the coin slot completed a circuit that triggered unauthorized coin releases. The bottom piece (a long wire) is fed up through the bottom hopper to reach the circuit affecting hopper control. The top piece (a thicker gauge wire bent in a “9” shape) is placed in the coin slot. Together they complete a circuit that triggers the hopper to dispense all stored coins.
On the record
Tommy Glenn Carmichael’s partner Ray Ming introduced him to the top-bottom joint in 1980. Carmichael used it for 20 years across the U.S. and Caribbean before his first arrest at age 35 resulted in a 5-year prison sentence.
Detection & prevention
The paid halfHow a monitoring room catches top-bottom joint, and what stops it recurring — written for the desk, not the reader.
Detection · 21 words
Prevention · 25 words
Published as a detection reference for surveillance, compliance and gaming-operations professionals. Thresholds and tuning are set by the property. Nothing here is instruction — the method is described so it can be recognised.