Lamp socket diode orientation and 555 socket contacts
On a 44/47 bayonet socket the diode band goes to the centre lug and the plain end to the top lug. On plug-in 555 sockets the small outer metal tabs are often bent so they no longer touch the lamp board; bend them back out for a good contact.
Systems
Related tips
- Test a lamp socket diode in place
- Several lamps in one matrix row won't light: rusty sockets, diodes and joints
- One insert stays dark with good bulbs and sockets: failed diode on its lamp board
- A group of clock lamps never light with good wiring: reseat the bulbs in their sockets
- Test each lamp column driver with a test lamp
- Test each lamp row driver with a test lamp
- How the CPU-controlled lamp matrix is wired
- Check the lamp matrix outputs with a logic probe
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)