Lamp Abnormality - Christie LX1750C Service Manual

Troubleshooting

Lamp abnormality

■ Lamps
- At first, the high-voltage pulse (about 8KVp-p) is generated between the
lamp electrodes to generate glow discharge. Then dielectric breakdown
occurs, finally glow discharge comes to arc discharge.
- After projector turned on, 30 seconds are required until the light output
stabilizes.
- After the projector is turned off, the cooling fans operate for 90 seconds
to cool down the lamp and reduce gas pressure inside the lamp. During
this period, the projector cannot turn on.
■ Lamp cover switches
Make sure that the lamp cover is mounted correctly. If not , the lamp does
not light for safety.
Check the stay of the lamp cover and the lamp cover switches.
SW77A and SW77B detect for Lamp 1
SW77C and SW77D detect for Lamp 2
SW77E and SW77F detect for Lamp 3
SW77G and SW77H detect for Lamp4
Switches -- open : Lamp cover is opened
■ Thermal fuses
When the internal temperature around the lamps reaches near 99ºC, the
thermal fuse will open and cut off the power supply to the PFC board.
SW903 - SW904 for Lamp 1 and 2 -- open : Abnormality
SW905 - SW906 for Lamp 3 and 4 -- open : Abnormality
■ LED status
LAMP REPLACE Indicator
- When the LAMP REPLACE indicator lights:
Any of the projection lamps is approaching its end
- When the LAMP REPLACE indicator flashes:
The lamp reached its end.
LAMP 1/2/3/4 REPLACE Indicators
- When any of the LAMP 1/2/3/4 REPLACE indicators lights:
The corresponding lamp is approaching its end.
- When any of the LAMP 1/2/3/4 REPLACE indicators flashes:
The corresponding lamp needs to be replaced
■ Lamp monitoring
- The CPU performs an input check by each lamp monitor signal (LAMP_
RX).
- When the lamp monitor signal becomes "H" for 1 second or more, the
CPU judges the state to be abnormal on its lamp.
- When the CPU detects abnormal condition, the CPU turns off a pair of 2
lamps which has an abnormality and the CPU uses another remaining a
pair of 2 lamps to keep the projector on.
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Check that the lamp on/off signals
(BALAST1_SW, BALAST2_SW,
BALAST3_SW, BALAST4_SW)
are correct.
Lamp-On: 3V, Off: 5V
Check that the lamp power drive
signals (PFC1_SW, PFC2_SW,
PFC3_SW, PFC4_SW) are cor-
rect.
Power-On: H
If the Lamp ID board is not mount-
ed firmly, the warning message will
appear on the screen and some of
the functions may be disabled.
LX1750 Service Manual
020-000643-01 Rev.1 (01-2014)