254Cable Shorts TestThis test determines if a cable has a short to ground or a pin-to-pin short (also called a wire-to-wire short). Such shorts can becaused by cables resting on or moving across sharp edges. The edges over time can wear away the plastic shielding of thecable, exposing the copper wire inside. A short occurs when the exposed wire touches another metal surface or conductor.This procedure tests only the cables listed below that can be disconnected at both ends:• Intermediate cables of devices in the Main Wire Harness Test Tables:Card Cage FanLeft Ribbon MotorRight Ribbon MotorExhaust Fan (in cabinet models)Magnetic Pick-up Unit (MPU)• Shuttle Motor Intermediate Cable• Hammer Bank Power and Logic Intermediate Cables• Operator Panel Assembly Intermediate Cable• Power Stacker Logic and Power (Intermediate) CablesThe Procedure:1. Prepare the printer for maintenance (page 313).2. Disconnect the cable to be tested at both ends, but leave the cable routing as it was before you started this procedure.3. Set your Ohmmeter to the 10K Ohm scale or the scale closest to 10K Ohms.4. Hold the two meter leads apart from each other (not touching anything) and note how your meter indicates an open circuit.For example, some meters read OL (Over Load), -1, flashing display, infinite resistance, etc. Record this indication for laterreference.Check for shorts to ground:5. Attach the common meter lead (usually black) to a ground point on the printer (e.g., a bolt head on the shuttle casting).6. Touch the positive meter lead (usually red) to another ground point and verify continuity. (Continuity is a low resistancereading of less than 1 Ohm.)
