On the LED test strip a coil output stays solidly on, or never blinks when it should.

Coil output LED solid on or never blinks

Cause: Solid on means a shorted driver transistor. Never blinking means the U14 command, the CA3081 pre-driver array or the driver transistor.

Checks

• Driver-test LEDs should blink one after another; basic-test LEDs blink together.
• Check the U14 outputs, pins 1-16, for pulses; if pulsing, the fault is in the pre-driver or driver (schematic sheet 5).

Fix

• Replace the shorted driver transistor (TIP102), or the CA3081 array or U14 as found.

Systems

• Bally 6803

Related tips

• Make an LED tester for lamp and coil outputs
• The 19 solenoid driver transistors
• Solenoid driver transistor types
• Test EPROM memory test does not pass
• Test EPROM socket signals at U3
• Expected LED-strip results on lamp headers J10-J13
• Test EPROM fitted but the LED does not blink
• An LED stays dark on a lamp header during the test

Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)