Brother International HL-720 Service Manual - Page 74

No DC power, Main motor unrotated

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M-2 Possible cause AC power supply Wiring, DC load No DC power li d Step 1 2 Check Is AC power supplied between connectors CN1-L and CN1-N when the power plug is plugged into the outlet? Turn the power switch OFF and disconnect the P4 connector (panel sensor PCB). Measure the voltages between the terminals. Do the measured voltage satisfy the prescribed value in the table below? Result No Yes Remedy Follow the same check procedure of M1 "No AC power supplied". Turn the power switch OFF, connect the connector disconnected, 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. Power supply 3 input unit No Replace the power supply input unit after unplugging the power cord from the power outlet. M-3 Main motor unrotated Possible cause Connection failure of connector Main motor (M1) Panel sensor circuit Step Check 1 Is the connection of connector P5 on the panel sensor PCB correct? 2 Disconnect connector P5 from the panel sensor PCB. Measure the resistance between the connector pins of the main motor by using a circuit tester. Do the measured resistance satisfy the prescribed value in the table below? Result Remedy No Reconnect the connector. No Replace the Main motor. Yes Replace the panel sensor PCB. Replace the Main PCB.

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M-2
No DC power
li d
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 the power switch OFF and
disconnect the P4 connector (panel
sensor PCB).
Measure the voltages between the
terminals.
Do the measured voltage satisfy the
prescribed value in the table below?
Yes
Turn the power switch
OFF, connect the
connector
disconnected, 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.
Power supply
input unit
3
No
Replace the power
supply input unit
after
unplugging the
power cord from the
power outlet
.
M-3
Main motor unrotated
Possible cause
Step
Check
Result
Remedy
Connection
failure of
connector
1
Is the connection of connector P5
on the panel sensor PCB correct?
No
Reconnect the
connector.
Main motor
(M1)
2
Disconnect connector P5 from the
panel sensor PCB.
Measure the resistance between
the connector pins of the main
motor by using a circuit tester.
No
Replace the Main
motor.
Panel sensor
circuit
Do the measured resistance satisfy
the prescribed value in the table
below?
Yes
Replace the panel
sensor PCB.
Replace the Main
PCB.