Sanyo PLV-55WHD1 Service Manual page 89

● Lamp control stage
BOOSTER
PWM
IC601
P.F.C.
<FA5502>
POWER BOARD
MAIN BOARD
● Description
Lamp Driving Circuit
Turn PTV on, LAMP_ON signal becomes to "H" and the lamp starts lighting.
The ballast output is about 140W at High and Mid mode, or about 115W at Low mode.
Lamp_Rx/Tx signals between IC801 and the ballast unit control the output of the ballast by UART.
Rx_LAMP signal (lamp error signal) becomes "H" and then the projection TV shuts down.
Turn PTV off, TV CPU shuts down the lamp after the period of LPS mode.
LPS Mode (Low Power Shutdown)
At LPS mode, the ballast output is keeping about 30W for about 4 minutes after turn-off.
When PTV is turned on during LPS mode, the lamp lights at once.
P.F.C. Circuit
Power factor control (P.F.C.) is performed by IC601
and the peripheral circuits. The output voltage
370V (at AC input = 230V) is supplied to the ballast.
The output voltage is adjusted with VR621.
Lamp Cover Switch and Thermal Switch
When the lamp cover switch or the thermal switch
is open, Lamp_ON signal will be cut off and the
lamp does not light for safety.
K6C CN1
DC INPUT
DC300~380V
18V 18V
PRIMARY CIRCUIT
UNIT_LAMP BALLAST
68
LAMP_TX
69
LAMP_RX
IC801
67
TV CPU
LAMP_SW
S5V
FAN_ERR
ERROR : L
FILTER FULL IGNITION
BUFFER BRIDGE CIRCUIT
CONTROL
CN2
4 3 1
4 3 1
K8L
ECO_mode
H = ECO, L = Normal
LPS_mode
H = LPS, L = OFF
IC1831
3
4
8 11
ERROR : H
K8S
IC1851
H = Lamp-ON
L = LPS or
Lamp-OFF
LAMP STATUS TIMING CHART
ON
LAMP_STATUS
OFF
H
LAMP_ON
(LAMP CON/SYNC Signal)
L
H
RX_LAMP
(LAMP_LIT Signal)
L
H
TX_LAMP
(ECO - LPS Signal)
L
-89-
Chassis Block Diagrams
CN3
LAMP
Output voltage.
at starting time : 2.4 - 3.6 KV
at normal : AC 70V typ.
Output Frequency : 180 Hz typ.
COVER SW
SW1861
BOARD
LAMP COVER SW
ERROR : Open K18S
1 3
JOINT BOARD
K18U
K18T K18V
3 1
SW902
THERMAL SW
ERROR : Open
Turn ON Turn OFF
Stable Period
LPS Mode
Error Detect Period
H = Low, L = High mode
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