Service manual

QMS 3260/4032 Laser Printer - Base Engine Technical Manual

2-3

Release Version 11-97

Fault Isolation Procedures

General Notes on Using FIPs

1. FIPs assume there is no malfunction in the printer controller (ESS). If you are unable to fix a problem

using the FIPS, we recommend that you replace the printer controller.

2. FIPs frequently use new or "known good" components as troubleshooting tools. We recommend you

carry a spare Print Cartridge (EP Cartridge), Fuser Assembly, MCU PWB, QMS Video Controller, and

LVPS PWB.

3. Unless indicated otherwise, the instruction "switch ON 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 on-line and

ready to print.

4. 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).

5. When you are 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.

6. When you are 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.

7. 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.

8. Unless a FIP instructs you otherwise; before measuring voltages make sure the printer is switched ON,

the Print Cartridge and the Paper Cassette are installed, and the Main Interlock Switch is actuated.

9. All voltage values given in the FIPs are approximate values. Actual measured voltages may

vary more than 25% from the values stated in the FIPs. The main purpose of most voltage read-

ings taken in the FIPs is to determine whether or not a component is receiving the correct HIGH

voltage value from the power supply and if gating (a voltage drop) occurs during component

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.

10. FIPs may instruct you to remove or replace a component. Refer to Section 10 Removal and Replace-

ment Procedures for information on how to remove and reinstall a component.

11. When a FIP instructs

ou to replace a component, and that component is part of a lar

er assembl

ou should replace the entire assembl