Canon LV-S3E/D78-5423, Service Manual

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Part 4: Troubleshooting
4-1
1. TROUBLESHOOTING
1.1 No Power
This projector provides a function which can be specified a defective area simply by
indicating the LEDs on the control panel. Connect the AC cord and press the Power
button once and then check the LED indication.
●
When all the LED indicators are not lighting, the symptom indicates that the primary
power supply circuit does not operate properly. Check the power primary circuit
and parts as follow;
• AC cord
• F601 (Fuse)
• Power board
• SW902 (Thermal sw.) .............................short in normal
SW902 opens when the surrounding temperature of the switch exceeds
100°C.
●
When the WARNING (red) and POWER (red) indicators are flashing,
the symptom
indicates that the projector detected an abnormal temperature risen inside the
projector. Check the air filters and remove the object near the intake and exhaust
fan openings, and wait until the POWER indicator stops flashing, and then try to
turn on the projector.
The internal temperature is monitored by sensor ICs, IC8821 on Sensor Board,
IC8801 and IC8802 on Main Board.
●
When the WARNING (red) indicator lights, the symptom indicates that the projector
detected an abnormality in the cooling fan operation or in the power supply
secondary circuits. Check fan operation and power supply lines, and the driving
signal status.
• An abnormality occurs on the secondary power supply lines.
Power failure detection diodes detect abnormal voltage on the power supply
circuits.
POWER_FAIL (Error:L) signals are sent to pin 174 of IC301(System
Controller) via IC1871(Comparator).
Check the shortage of secondary circuits, ICs, condensers, etc.
Check power supply lines, 15VP, 9V, 3.3V and 1.8V on the Main Board.
• An abnormality occurs on the fan control circuits.
Power failure detection diodes detect the fan operation stop. Check FN901,
FN902, FN903, FN904, FN905, FN906 and peripheral circuit.
Check fan's power supply lines and detection diodes D5612, D5619 and
D5624.
Check fan lock signal (Lock:H) and Q5611, D5622 and peripheral circuit.