Brother International HL-1070 Service Manual - Page 86

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 No AC power supplied Possible cause Supply voltage Power plug Fuse (F1, F2) Wiring Step 1 Check 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? Result No No Yes Yes 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. M-2 No DC power supplied Possible cause AC power supply Wiring, DC load Low-voltage power supply PCB 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 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 Voltage Driver P13-4.5 P13-2.3 Approx. 24V P13-8.9 P13-6.7 Approx. 5V Result No Yes No 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. Caution: 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. IV-22