60
27. Grand Wega Lamp Control
+
-
1
3
2
1
2
3
3
12 13
4
5
40
39
50
49
48
IC9502 LAMP
CONTROL
IC9004
MAIN
MICRO
4
4
*
G BD.
A BD.
M BD.
H3 BD.
T BD.
0V
25kV TO GAS
DISCHARGE
LAMP
R1613
N/C
R1654
R1655
F1601
6.3A
POWER
SUPPLY
POWER
S8001
N/C
HV
DET
CN
4502
S DATA
CLK
WIRE
COLOR
WHI GRY
CTL=
ON=5V
OFF=0V
CN1908
CN1901
POWER
BLOCK BD.
PRT
=0V
LAMP COVER
BOARD
270V
CN1602
CN1920/
CN9501
40
LAMP COMES ON
1 WHEN CN1908/PIN 1 = 5V
2 POWER BLOCK BD.
OUTPUTS 27kV IGNITION
VOLTAGE , THEN 25kV RUN
VOLTAGE
TV
BLOCK
FIGURE 27-1 - LAMP CONTROL - KF-60DX100
M BD.
HV
POWER
BLOCK
HV DET
WIRE
TV FRONT
1
2
6TVP13 1439
4/16/02
45
7
7
STBY LED
LAMP DEFECTIVE -
STBY LED BLINKS CONTINUOUSLY
POWER BLOCK BD. DEFECTIVE -
STBY LED BLINKS 5 TIMES
LAMP COVER SW. OPEN -
STBY LED BLINKS 3 TIMES
MAIN
P.S.
0V
5V
*
255V-
350V
G1
SPARK GAP
G1
New HV Detector Circuit
The purpose of the HV Detector circuit (on the M board) is to identify the cause of no backlight. The front panels
LEDs use this information. The LAMP LED blinks continuously if the lamp is defective or the Standby LED will
blink five times if the HV or control circuitry is bad. Refer to Figure 27-1 for the following HV detector circuit
description:
Normal Operation - At power ON, Main Micro IC9004 instructs Lamp Control IC9502 (both on M board) to output
a HIGH at Ctl (A board, CN1908/pin 1). This HIGH is applied to the Power Block to start the 25kV necessary for
the lamp ignition. If the lamp starts to draw current, the Power Block closes the relay to reduce lamp voltage and
grounds the PRT line (CN1908/pin 3 or the end gray wire on the Power Block).
The PRT (protect) line is a signal to tell the Main Micro the lamp is drawing current (working). When LOW
(0Vdc), the Main Micro in turn unmutes the A/V lines and a picture with sound appears (all within 20 seconds after
turn ON).
Defect - The LAMP LED blinks continuously - The main Micro looks at the PRT signal (CN1908/pin 3) and the
antenna signal to determine if the lamp or Power Block is defective (Table 27-1). When HV appears without a
load (bad bulb), arcing in the spark gap on the Power Block creates RF that is picked up by the nearby antenna
wire. This RF signal is brought back to the A board at CN1908/pin 12. The RF signal only passes through the A
board to get to the M board (CN9501/pin 50) where it is rectified. On the M board, a DC voltage developed after
the RF signal is rectified indicates the presence of HV (normal Power Block operation). If there is HV and no
current draw, the conclusion is that the lamp is bad so the Main Micro continuously blinks the front panel LAMP
LED.