Brother MFC-8220, Service Manual

Page: 198 / 328

CHAPTER 6 TROUBLESHOOTING
6-20
5. MALFUNCTIONS
When taking countermeasures for malfunctions as described in this section, check connectors
for contact failure before measuring the voltage at the specified connector pins.
M-1 No AC power supplied
Possible cause Step Check Result Remedy
Supply voltage 1 Is the correct voltage present
at the outlet? No Inform the user that the
correct voltage is not supplied
at the outlet.
Power plug 2 Is the power cord securely
plugged into the outlet? No Plug the power cord securely
into the outlet.
Fuse (F1, F2) 3 Is the fuse blown? Yes If the fuse blows again
immediately after replacing
the low-voltage power supply
PCB, check that there is not a
short circuit somewhere in the
AC power supply line.
Wiring 4 Unplug the power supply plug.
Is there a broken wire between
the AC input connector of the
low-voltage power supply and
the power plug? Yes Replace the AC power cord.
M-2 No DC power supplied
Possible cause Step Check Result Remedy
AC power
supply 1 Is AC power supplied between
connectors CN1-L and CN1-N
when the power plug is
plugged into the outlet? No Follow the same check
procedure of M-1 “No AC
power supplied”.
Wiring, DC load 2 Turn on the power switch.
Measure the voltages between
the terminals. Do the
measured voltage satisfy the
prescribed valued in the table
below? Yes Turn off the power switch,
reconnect the connector and
turn the power switch on
again. If the protector circuit
is activated, check the
connector, the wiring from the
connector, and the DC load.
Low-voltage
power supply
PCB 3 Refer to the chart *1 below. No Replace the low-voltage
power supply PCB.
*1
PCB +lead pin - lead pin Voltage
Engine CN8-3
CN10-6
CN8-2
CN10-5 Approx. 24V
Approx. 3.3V
WARNING
If you analyze malfunctions with the power plug inserted into the power outlet, special
caution should be exercised even if the power switch is OFF because it is a single pole
switch.