Troubleshooting; Introduction; Precautions; Checking Prior To Troubleshooting - Brother MFC5890CN Service Manual

4.2

TROUBLESHOOTING

4.2.1 Introduction

This section gives the service personnel some of the troubleshooting procedures to be followed
if an error or malfunction occurs with the machine. It is impossible to anticipate all of the
possible problems which may occur in future and determine the troubleshooting procedures, so
this section covers some sample problems. However, those samples will help service personnel
pinpoint and repair other defective elements if he/she analyzes and examines them well.

4.2.2 Precautions

Be sure to observe the following to prevent the secondary troubles from happening in addition
to the safety precautions given in
Always unplug the AC power cord from the outlet when removing the covers and PCBs,
adjusting the mechanisms, or conducting continuity testing with a circuit tester.
(1) When disconnecting the connectors, do not pull the lead wires but hold the connector
housings.
(2) Static electricity charged in your body may damage electronic parts.
Before handling the PCBs, touch a metal portion of the machine to discharge static
electricity charged in your body. When transporting PCBs, be sure to wrap them in
conductive sheets.
When replacing the head/carriage unit, put on a grounding wrist band and perform the job
on a static mat. Also take care not to touch the conductor sections on the flat cables.
After repairing the defective section, be sure to check again if the repaired section works
correctly. Also record the troubleshooting procedure so that it would be of use for future trouble
occurrence.

4.2.3 Checking Prior to Troubleshooting

Prior to proceeding to the troubleshooting procedures given in
following initial checks:
Environmental conditions
Check that:
(1) The machine is placed on a flat, firm surface.
(2) The machine is used in a clean environment at or near normal room temperature (10°C to
35°C) with normal relative humidity (20 to 80%).
(3) The machine is not exposed to direct sunlight or harmful gases.
Power requirements
Check that:
(1) The power supply specified on the rating plate on the machine is used. The supply voltage
stays within the rating ±10%.
(2) Each voltage level on AC input lines and DC lines is correct.
(3) All cables and harnesses are firmly connected.
Chapter 6, Section 6.1.
WARNING
4-31
Section 4.2.4, make the
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