21 Introduction

Le Mans is a fairly complex video game, and the operation of the circuitry must be learned before your troubleshooting attempts will be successful. However, after the basic differences are understood, it should prove no more difficult than any other Atari PCB. The main differences between Le Mans and previous Atari games are the steering circuitry, the ROMs and the power supply. The steering circuitry is a novel bit atertgineer-ing which employs phototransistors and infrared light-emitting...

214 Steering Control

The two infrared light-emitting diodes (LEDs) mounted on the steering assembly PCB are aimed directly at the two phototransistors. As the slotted steering ring rotates, the path of light is broken up causing the phototransistors to pulse in a way which corresponds to the direction of the steering wheel rotation. These pulses are fed into four-input Schmitt triggers (J8) which clean up the pulses so the flip-flops can be triggered consistently. When the steering wheel is turned in a clockwise...