Coil diode polarity
A diode across a DC coil must have its cathode (banded end) on the positive supply side. Fitted backwards it shorts the supply when the coil is driven.
Systems
- Williams System 3
- Williams System 4
- Williams System 6 / 6A
- Williams System 7
- Williams System 9
- Williams System 11
- Williams System 11A
- Williams System 11B
- Williams System 11C
- WPC Alpha-Numeric
- WPC Dot Matrix
- WPC Fliptronics
- WPC DCS
- WPC-Security (WPC-S)
- WPC-95
- Bally MPU AS-2518-17
- Bally MPU AS-2518-35
- Stern MPU-100
- Stern MPU-200
- Bally 6803
- Gottlieb System 1
- Gottlieb System 80
- Gottlieb System 80A
- Gottlieb System 80B
- Gottlieb System 3
- Data East CPU Version 1/2
- Data East CPU Version 3
- Data East/Sega CPU Version 3b
- Capcom
Related tips
- Testing the diode on a coil
- Testing a coil diode
- What a bad coil diode does
- Which way a coil diode goes
- Which way a coil diode goes
- What the coil diode does and how a bad one shows up
- Protect coil diodes with a heat sink
- Diodes on coils: EM and solid-state coils are not interchangeable as-is
Source: Pinball Machines: How They Work & Troubleshooting, Norbert Snicer