No Power - Canon LV-7545U Service Manual

1. TROUBLESHOOTING

1.1 No Power

The following items are suspected as possible causes of "no power". Check the items
by referring to the block diagrams of the power supply circuit and protection circuit on
the next page.
1) The power supply circuit stopped operation because an abnormality was detected.
An abnormality was detected in the secondary power side.
The power abnormality detection diode detected an abnormal voltage in the power
supply. Check the secondary side power circuit, ICs and capacitors for shorting.
Check the power line 9VA and 15.7V on the drive unit and power line S5V, 5VD, 9V
and 15.5V on the main board.
Check detection diodes D1653 and D1604 on the drive unit and D2304, D3301,
D3571, D3501 and D2592 on the main board.
The cooling fan stopped.
The power abnormality detection diode detected stoppage of the cooling fan.
Check fans FN901, FN003, FN903, FN904, FN905 and FN906.
Check the fan supply power line and detection diodes D6610, D6612, D6613,
D6614, D6616, and Q6609.
An abnormal internal temperature rise of the projector was detected.
The temperature sensor IC detected an abnormal temperature. Check the
peripheral circuits, sensor IC IC1691 on the TEMP unit and IC1871 and IC1872 on
the main board.
The thermal switch (SW905) detected an abnormal temperature. Check the SW905
and its peripheral circuits.
When the SW905 is normal, it is shorted.
The SW905 is opened when the temperature exceeds 90˚C.
An error occurred in the lamp ballast unit.
The lamp ballast unit outputs an error signal (LAMP_DET) to pin 123 of IC801.
LAMP_DET ........................................Abnormal: High
The power supply circuit detected overload/overvoltage in the power supply circuit.
The feedback circuit detected overload or overvoltage. Check PC602 and its
peripheral circuits.
The protection mechanism of the interlock switch (SW902) was activated.
Check whether the lamp cover is correctly installed.
The fuse (F601) is blown.
4-1
Part 4: Troubleshooting