Sony D98 chassis Operation Manual page 25

Active
Video
From
IC001
ASC
Measurement
From N
Timing
Board
Analysis
Display
To
Controller
IC001
IC003
R080
D024
5V IC009
C106 Regulator
3) Color Restoration doesn't work. Bad color after restoration, check:
- That the OSD is working. If not follow steps of 1).
- BCF registers on the Color Table. Look to see if any registers are abnormally low or high.
The following are typical ranges:
Mode 1
R BCF 110~140
G BCF 115~145
B BCF 125~155
If values seem strange, check voltages at the BCF pins (20,21,22) of IC003. With a full white image the voltage should be
around 2.5~4.5V. If levels seem strange check beam current sensing circuit (next section).
3. G2 and Beam Current Sensing
G2 Amplifier
The G2 reference is provided to IC005 Pin 5 by the IC001 D/A converter. The G2 voltage at the cathode is typically 500v ~
750V.
Beam Current Sensing Circuit
Sensing resistors R108, R208, and R308 convert the beam current flowing through the cutoff amplifier during the blanking
time into a voltage. This voltage is then AC coupled and clamped to ground. It is then rectified to a DC voltage and sent to
the A/D converters of IC003. Here it is converted to digital format and stored in the RGB BCF registers.
Troubleshooting Hints
1) If picture is black, check:
- G2 level at the cathode using HV probe.
- Input to G2 amp, Pin 5 of IC005.
Cutoff
Control
D/A from
Red
IC001
Green
Blue
Beam Current
Measurement
Beam
Current
Same as R
channel
A/D
C037
PLL
From N
2
IC
Board
Interface
R003
C038
Oscill
ator
Mode 2
130~160
90~120
45~80
+12V +80V
IC003
10 6
8 5
9 3
1
11
Video
Driver
Cutoff Circuit
R119
R107
R120
C105
R105
IC004
4
7
Simillar to 10
9
Red Channel - V-
V+
+
13
R108
R116
C121
R122
Beam Current Sensing Circuit
Mode 3
105~135
130~160
180~230
- -
25
D104
C106
C206
CRT
C306
+B
D106
D206
+B +B
D306
R219 R316
R220
R320
D108
R115
C108
D120