Thing Down Opto
Matrix column 8, row 4 · under the playfield ·
Wiring
- Column 8
- Green-Grey J206-9 · U20-11
- Row 4
- White-Yellow J208-4 · U18-7
Parts
- Assembly A-15285
Location
Owner's hint
Opto sensor (transmitter + receiver). Check +12 V and ground to the opto board, and that nothing blocks the beam. (owner's experience, not the manual)
Related
Service log
Everything you record stays on this device.
Service notes: In the switch matrix at column 8 (J206-9, U20-11) and row 4 (J208-4, U18-7). An opto pair: the LED side runs from 12 V through a series resistor on the small board, the phototransistor pulls the row. A phone camera shows the LED as a glow; a blocked, dusty or misaligned opto reads closed. One switch that fails T.1 is its gap, the wire at the lug or its diode; a shorted diode makes the whole column or row misread. A whole column dead is U20 or the J206 pin, a whole row is the row comparator. A3 Switches and optos
Appendices:A3 Switches and optosA5 Power driver boardA1 Multimeter basics