3-12 Phaser 7400 Color Printer Options Service ManualMeasurement Techniques1. Unless indicated otherwise, the instruction “switch On printer power” means foryou to switch On printer power and let the printer proceed through Power OnSelf Test (POST) to a ‘Ready’ condition.2. Conventions used in this manual to represent connectors3. When instructed to take voltage, continuity or resistance readings on wiringharness, proceed as follows; Check P/J 232–1 to P/J 210–5 by placing the redprobe (+) of your meter on pin 1 of P/J 232, and place the black probe (–) of yourmeter on pin 5 of P/J 210.4. When you are instructed to take resistance readings between “P/J 232 <=>P/J 210” (without specified pin numbers), check all pins. When you areinstructed to run a test, run the Service Diagnostics test associated with thecomponent being examined.5. When you are instructed to take a voltage reading, the black probe (–) isgenerally connected to a pin that is either RTN (Return) or SG (Signal Ground).You can substitute any RTN pin or test point in the printer, and you can use FG(frame ground) in place of any SG pin or test point.6. Before measuring voltages make sure the printer is switched On, the ImagingUnit and the paper trays are in place, and the interlock switch is actuated, unless atroubleshooting procedure instructs otherwise.7. All voltage values given in the troubleshooting procedures are approximatevalues. The main purpose of voltage readings is to determine whether or not acomponent is receiving the correct voltage value from the power supply and ifgating (a voltage drop) occurs during component actuation. Gating signals maybe nothing more than a pulse, resulting in a momentary drop in voltage that maybe difficult or impossible to read on the average multi-meter.8. When a troubleshooting procedure instructs you to replace a non-sparedcomponent and that component is part of a parent assembly, you should replacethe entire parent assembly.9. Ensure that you are using a supported media size and type.10. Power and signal grounds are connected to the frame ground. All circuittroubleshooting can be performed using the metal frame (chassis) as thegrounding point.s7400-314PlugJack
