Check every coil's resistance before first power-up
Steps
- With the game unplugged, set the meter to its lowest ohms range.
- Put the leads across each coil's two lugs; expect 2 ohms or more (a slingshot coil A-1496 reads about 3.4 ohms).
- For any reading under 2 ohms, take one wire off a lug and measure again.
- If it is still low, the coil or its diode is bad; clip one diode leg and measure once more to tell which.
- If it is now above 2 ohms, the coil is fine but the transistor driving it is shorted.
Systems
Related tips
- Check every coil's resistance before first power-up
- Testing the diode on a coil
- Game Over (Q) and Tilt (T) relays are not fused
- Testing coil diodes on the auxiliary power driver board
- Wire an A-16890 relay coil to run on EM AC power
- Testing a coil diode
- Flipper stuck up with power on (Playboy and later)
- Which way a coil diode goes
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)