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Service Adjustments (Electronic Controls, cont.)
Procedure:
1.
In the Serviceman Mode for making electronic
adjustments, select DAC Sub-Tint Adjustment
(B1). Adjust until the waveform measured is as the
one shown in Fig. 19.
2.
Connect the oscilloscope to TP47G (A-Board).
3.
Select DAC Sub-Color Adjustment (B0) and adjust
for peak to peak amplitude to be as shown in
Fig. 20.
4.
Remove the jumpers (Preparation steps 4 & 5).
Color Temperature Adjustment
(B/W Tracking)
Serviceman DAC Adjust. (C1) (C2) (C3) (C4) (C5)
Minor Touch-Up Method
OBSERVE low and high brightness areas of a B/W
picture for proper tracking. Adjust only as required for
“good gray scale and warm highlights”.
1.
LOW LIGHT areas – In Serviceman Mode for
making electronic adjustments, select Cutoff (C0)
RED, (C1) GRN, (C2) BLU and adjust the picture
for gray.
2.
HIGH LIGHT areas – In Serviceman Mode for
making electronic adjustments, select Drive (C3)
RED, (C4) BLU and adjust the picture for
warm whites.
Complete Adjustment
Preparation:
1.
Turn the Receiver “ON” and allow 10 minutes
warm up at high brightness.
2.
Apply a color bar signal with color “OFF”.
3.
Turn the SCREEN control (part of FBT T551) fully
counterclockwise.
Procedure:
Preset the following Serviceman DACs for best results:
• C0 . . . . . . . . . 0 128
• C1 . . . . . . . . . . . 64
• C2 . . . . . . . . . 0 128
• C3 . . . . . . . . . . . 64
• C4 . . . . . . . . . . . 64
1.
Connect the oscilloscope to C1-2 (CRT-Board).
2.
In Serviceman Mode for making electronic
adjustment, select the Sub-Bright DAC (B2).
3.
Press the R-Tune key on the remote.
4.
Observe the oscilloscope waveform at Horizontal
rate and adjust the Serviceman Mode Sub-Bright
DAC (B2) level until a scanning period of 3.0V
above DC ground is measured, as indicated in
Fig. 21.
5.
Connect the scope to GRN Cathode (KG) on the
CRT-Board.
6.
In the Serviceman Mode for making electronic
adjustments, select the GREEN CUTOFF
DAC (C1).
7.
Press the R-Tune key on the remote.
8.
View scope trace at Horizontal rate and adjust the
Serviceman Mode DAC (C1) level until a scanning
period of voltage above DC ground is measured,
as indicated in Fig. 22.
9.
Connect the scope to the RED Cathode (KR).
10. In Serviceman Mode for making electronic
adjustments, select the RED CUTOFF DAC (C0).
11. Press the R-Tune key on the Remote
12. View the scope trace and adjust the Serviceman
Mode DAC (C0) for the scanning period to be 195V
for 27”&32” and 185V for 25” above DC ground.
(Fig. 22)
13. Connect the scope to the BLUE Cathode (KB).
14. In Serviceman Mode for making electronic
adjustments, select the BLUE CUTOFF (C2).
15. Press the R-Tune key on the Remote.
16. View the scope trace and adjust the Serviceman
Mode DAC (C2) for the scanning period to be
27”&32” and 185V for 25” above DC ground. (See
Fig. 22)
17. Turn the Screen Control (part of FBT) slowly
clockwise until a color horizontal line appears.
18. With the other two colors Serviceman Mode DAC
CUTOFF adjustments (C0) RED, (C2) BLUE;
increase the colors to create a white horizontal line.
19. Confirm that a good gray scale is established by
viewing B/W color bar pattern.
20. In the Serviceman Mode for making electronic
adjustments select the DAC DRIVE adjustments
(C3) RED, (C4) BLUE and adjust for warm white in
a white color bar pattern.
A to B = 1 unit
A
C
1 2 3
10
4 5 6 7 8 9
B
B to C = 2 units
Figure 19. TP47B waveform
TP47B (A-Board)
B
2
C
x 1
1 2 3 4 5 6
7 8 9 10
Figure 20. TP47G waveform
TP47G (A-Board)
0.85±0.05Vpp(27”)
0.80±0.05Vpp(25&32”)
0V DC
Figure 21. TP35 Waveform
3.0V DC
Figure 22. Cathode Waveform, Adjustment
Waveform Detail
195V DC(27”& 32”)
0V DC
(Ground)
185V DC(25”)
