One or more (not all) controlled coils do not fire, or stay energized.
Some CPU-controlled coils are dead or locked on
Cause: A failed coil, a shorted or open coil diode, a blown individual playfield coil fuse, a failed driver transistor, or the control board.
Checks
- Check the coil itself.
- Check the diode across the coil.
- Check that coil's individual playfield fuse.
Fix
- Replace the bad coil, diode or fuse; then the driver board, then the control board.
Never let any coil stay energized for more than about 10 seconds; switch off at once if one locks on.
Systems
Related tips
- Coil command lines during test step 17
- None of the controlled playfield lamps work
- One or more controlled lamps never light or stay on
- A driver board output is stuck on or dead
- Find out first whether a coil is CPU-controlled
- Driver board A3-J4 coil outputs
- How driver board coil transistors are switched
- Where coil, sound and lamp commands come from
Source: System 80 Service Manual, Gottlieb