Troubleshooting Malfunctions - Brother HL-1070 Service Manual

5.

TROUBLESHOOTING MALFUNCTIONS

When carrying out countermeasures for malfunctions as described in this section, check
connectors for contact failure before measuring the voltage at the specified connector
pins.
M-1
Possible cause
Supply voltage
Power plug
Fuse (F1, F2)
Wiring
M-2
Possible cause
AC power
supply
Wiring, DC load
Low-voltage
power supply
PCB
Caution: If you analyze malfunctions with the power plug inserted into the power outlet,
Download Free Service Manual and Resetter Printer at http://printer1.blogspot.com
No AC power supplied
Step
1 Is the correct voltage present
at the outlet?
2 Is the power cord securely
plugged into the outlet?
3 is the fuse blown?
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?
No DC power supplied
Step
1 Is AC power supplied between
connectors CN1-L and CN1-N
when the power plug is
plugged into the outlet?
2 Turn the power switch OFF
and disconnect the P13
connector (Driver PCB).
Turn the power switch ON
again. Measure the voltages
between the terminals.
Do the measured voltage
satisfy the prescribed value in
the table below?
PCB + lead pin - lead pin
Driver P13-4.5
P13-8.9
special caution should be exercised even if the power switch is OFF because it
is a single pole switch.
Check Result
No
No
Yes
Yes
Check Result
No
Yes
No
Voltage
P13-2.3 Approx. 24V
P13-6.7 Approx. 5V
IV-22
Remedy
Inform the user that the correct
voltage is not supplied at the
outlet.
Plug the power cord securely
into the outlet.
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.
Replace the AC power cord.
Remedy
Follow the same check
procedure of M-1 "No AC
power supplied".
Turn the power switch OFF,
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.
Replace the low-voltage power
supply PCB.