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4. Lamp Control
Lamp Driving Circuit
Lamps on and off are carried out by signal "BALAST1_SW" and "BALAST2_SW". IC801<CPU> sends IC4802<I/O
EXPANDER> the lamp on/off signal through the parallel bus. IC4802 outputs the lamp drive signals from pins 34
and 35 and sends to the Lamp Ballast Unit via the IC5825<BUFFER> as the name of "BALAST1_SW" and "BAL-
AST2_SW".
The signals "LAMP1_TXD", "LAMP1_RXD","LAMP2_TXD" and "LAMP2_RXD" are sent to Balast1 and Balast2 via
IC4751<INVERTER>. IC801<CPU> communicates Ballast1 and Balast2 with these signals to control the each lamp.
When an abnormality occurs at the lamp or ballast, the error signals "LAMP1_RX_EX" and "LAMP2_RX_EX" output
from the ballast unit is sent to pins 167 and 168 of IC801<CPU> through IC4751<INVERTER>. Then IC801 sends
driving signals "BALAST1_SW" and "BALAST2_SW" to ballast unit to stop operating of the ballast unit which has a
failure.
Power Supply Circuit
Signals "BALAST1_S" and "BALAST2_SW" are applied to POWER 1(AC) unit and POWER 2(AC) unit as the signal
"LAMP1_SW" and "LAMP2_SW" respectively. These signals drive the output power of lamp ballast. Signal "PFC_SW"
output from pin 36 of IC4802<I/O EXPANDER> is applied to power control circuit of POWER 1(AC)/POWER 2(AC)
through the IC5825<BUFFER>. The power control signal "POWER_SW_CPU" output from pin 211 of IC801 is applied
to power switching circuit of POWER (DC) unit through the IC5825.
Lamp Cover Switch (SW902/SW905), Thermal Switch(SW914)
When the Lamp Cover is not fixed securely, the switches SW902/SW904<LAMP COVER SW> do not turn on. The
signal "LAMP_COVER" passing through the SW902/SW904 is applied to pin 2 of IC9870<OR>. The signal "MS_
THERMO" output from the thermal switch <SW914> for the mechanical-shutter is applied on pin 1 of IC9870. When
either the input signal "LAMP_COVER" or "MS_THERMO" becomes "High", the output signal "LAMP_STOP" on pin
4 becomes "High", and the cuts off Q9802. As the result, the power supply for the lamp ballast unit is cut off and the
lamp ballast unit stops operating.
Thermal Switch (SW911/SW912)
The signal "SHUTDOWN1" becomes "High" and stops lamp ballast unit operation if the below cases happen.
- The temperature of Lamp1 or Lamp2 exceeds a certain value. (SW911 or SW912 turns off)
[NO POWER]
Point of Repair
When am abnormality occurs on the Lamp1, Lamp2, Ballast1 or Ballast2, projector cannot turn on due to operate the
protection circuit. Also if Lamp Cover or Bottom Cover is not fixed securely, projector cannot turn on due to operate
the protection circuit.
LAMP
REPLACE1
WARMING
TEMP
WARNING
FILTER
LAMP READY SHUTTER
LAMP
REPLACE2
Failure Parts
[SIgnals]
❂ ● ❂
SW902 or SW905 is opening
[LAMPCOVER: High]
❂ ● ●
Lamp1 failuer
[LAMP1_RXD: High]
● ● ❂
Lamp2 failuer
[LAMP2_RXD: High]
❂ ● ●
SW914
[MS_THERMO: High]
SW904, SW911, SW912
[SHUTDOWN1: High]
● ...... LED lightning
❂ ...... LED blinking
LED Indication in the Lamp Failure
Chassis Description & Troubleshooting
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