3.
TROUBLESHOOTING OF MALFUNCTIONS
Always turn off the power switch and unplug the power cord from the power outlet before
accessing any parts inside the printer.
In case that you analyze malfunctions with the plug inserted into the outlet, such as
checking the supply voltage, special caution should be exercised even if the power
switch is OFF because it is one way off type. Touching the power supply PCB may
cause to struck you by electricity.
When carrying out the countermeasures for malfunctions described in this section, make
sure to check connectors for contact failure before measuring the voltage at 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)
3
Is the fuse blown?
Yes
If the fuse blows again
immediately after
replacing low-voltage
power supply PCB.
Check if there is 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.
Summary of Contents for HL-720
Page 1: ...SERVICE MANUAL MODEL HL 720 730 730Plus R LASER PRINTER ...
Page 36: ...II 19 1 3 10 Engine I O HL 720 Fig 2 21 shows the engine interface circuit Fig 2 21 ...
Page 37: ...II 20 HL 730 730Plus Fig 2 22 shows the engine interface circuit Fig 2 22 ...
Page 61: ... Fig 3 18 2 4 1 1 1 ...
Page 92: ...SERVICE MANUAL MODEL HL 760 R LASER PRINTER ...
Page 109: ...II 8 1 3 4 DRAM Two 4M bit DRAMs x 16bits are used as the RAM Fig 2 6 ...
Page 113: ...II 12 1 3 10 Engine I O Fig 2 12 shows the engine interface circuit Fig 2 12 ...
Page 114: ...II 13 1 3 11 Paper Feed Motor Drive Circuit Fig 2 13 ...
Page 133: ...Appendix 2 Main PCB Circuit Diagram 1 3 CODE UK3227000 B48K272CIR 1 3 NAME ...
Page 134: ...Appendix 3 Main PCB Circuit Diagram 2 3 CODE UK3227000 B48K272CIR 2 3 NAME ...
Page 135: ...CODE UK3227000 B48K272CIR 3 3 NAME Appendix 4 Main PCB Circuit Diagram 3 3 ...