2-12 Service Manual
4022-XXX
Notes on Using Service Checks
1. Unless indicated otherwise, the instruction “switch on printer main power” means for
you to switch on printer power and let the printer proceed through power-on
diagnostics and warm-up until it is online and ready to print.
2. Conventions used to represent connectors:
P/J XX means a Plug and its corresponding Jack are connected.
PXX means a Plug is disconnected. (Unless this plug is soldered to a PWB).
JXX means a Jack is disconnected. (Unless this jack is soldered to a PWB).
3. When instructed to take a voltage reading between “P/J A–B and P/J X–Y,” place the
red probe (+) of your meter on pin B of P/J A, and place the black probe
(–) of your meter on pin Y of P/J X.
4. When instructed to take voltage readings between “P/J X and P/J Y” (without
specified pin numbers), check all voltage carrying pins. Refer to the Wiring Diagrams
for signals and pin numbers.
5. When 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.
6. Unless a service check instructs you otherwise; before measuring voltages make
sure the printer is switched on, the Xerographic Cartridge and the Paper Cassettes
are in place, and all of the interlock switches are actuated.
7. All voltage values given in the service checks are approximate values. Actual
measured voltages may vary more than 25% from the values stated. The main
purpose of most voltage readings taken is to determine whether or not a FRU is
receiving the correct voltage value from the power supply and if gating (a voltage
drop) occurs during FRU actuation. Gating signals may be nothing more than a
pulse, resulting in a momentary drop in voltage that may be difficult or impossible to
read on the average multimeter.
8. Service checks may instruct you to remove or replace a FRU. See Removal and
Replacement Procedures for information on how to remove and reinstall a FRU.
9. When a service check instructs you to replace a FRU, and that FRU is part of a
larger assembly, you should replace the entire assembly.
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