Shorted lamp sockets kill MPS-A13 drivers

An MPS-A13 is easily damaged if the lamp supply is shorted straight to its return wire with no bulb load, usually by a damaged bulb or socket. Fix the socket before replacing the transistor.

Systems

• Gottlieb System 1

Related tips

• Testing a CPU lamp circuit by grounding its driver
• How CPU-controlled lamps are driven
• No CPU controlled lamps light
• Testing MPS-A13 and MPS-U45 driver transistors
• Many lamp faults are driver board connectors
• A shorted coil means replacing its whole driver path
• Early driver boards lack isolation diodes
• System 1 driver board connectors

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)