Xerox Phaser 7750DXF, Service Manual, Page: 72 / 505

3-6 Phaser 7750 Printer Service Manual
General Notes on Troubleshooting
1.
Unless indicated otherwise, the instruction “turn ON printer power” means for
you to switch ON the printer power and let the printer proceed through POST to a
‘Ready’ condition.
2. When instructed to take resistance readings between “P/J 232 <=> P/J 210”
(without specified pin numbers), check all pins. See "Wiring Diagrams" on
page 10-1 for the location of all wiring harnesses and pins.
3. When you are instructed to take a voltage reading, the black probe (–) is
generally 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.
4. Before measuring voltages, make sure the printer is switched ON, the imaging
units and the paper trays are in place, and the interlock switches are actuated,
unless a troubleshooting procedure instructs otherwise. Before measuring
continuity or resistance, make sure the printer is switch OFF.
5. All voltage values given in the troubleshooting procedures are approximate
values. The main purpose of voltage readings is to determine whether or not a
component is receiving the correct voltage value from the power supply and if
gating (a voltage drop) occurs during component actuation.
6. When a troubleshooting procedure instructs you to replace a non-spared
component and that component is part of a parent assembly, replace the entire
parent assembly.