Electrical Adjustments - Toshiba 21N21B2 Service Manual

1. ADJUSTMENT PROCEDURE
Read and perform these adjustments when repairing the
circuits or replacing electrical parts or PCB assemblies.
CAUTION
• Use an isolation transformer when performing any
service on this chassis.
• Before removing the anode cap, discharge electricity
because it contains high voltage.
• When removing a PCB or related component, after
unfastening or changing a wire, be sure to put the wire
back in its original position.
• When you exchange IC and Transistor for a heat sink,
apply the silicon grease on the contact section of the
heat sink. Before applying new silicon grease, remove all
the old silicon grease. (Old grease may cause damages
to the IC and Transistor).
Prepare the following measurement tools for electrical
adjustments.
1. Oscilloscope
2. Digital Voltmeter
3. Pattern Generator
On-Screen Display Adjustment
1. In the condition of NO indication on the screen.
Press the VOL. DOWN button on the set and the
Channel button (9) on the remote control for more than
2 seconds to appear the adjustment mode on the
screen as shown in Fig. 1-1.
35 H POSI OSD
36 V POSI OSD
37 H POSI TEXT
38 V POSI TEXT
39 H POSI 60
00 CUT OFF
9- EXT
2. Use the Channel button (0-9) or Channel UP/DOWN
button on the remote control to select the options
shown in Fig. 1-2.
3. Press the MENU button on the remote control to end
the adjustments.
NO. FUNCTION
00 CUT OFF
01 RF AGC
02 AGC GAIN
03 R DRIVE
04 R CUTOFF
05 G DRIVE
06 G CUTOFF
07 B DRIVE
08 H POSI (50)
09 V POSI (50)
10 V POSI (60)
11 V SIZE (50)
12 V SIZE (60)
13 VCO COARSE
14 VCO FINE
15 VCO COARSE L1
16 VCO FINE L1
17 BRIGHT CENT
18 BRIGHT MAX
19 BRIGHT MIN

ELECTRICAL ADJUSTMENTS

120
57
119
57
34
VCO Status -
MMM
Fig. 1-1
NO. FUNCTION
20 TINT
21 SHARP
22 CONTRAST CENT
23 CONTRAST MAX
24 CONTRAST MIN
25 COLOR CENT
26 COLOR MAX
27 COLOR MIN
28 M R CUT OFF
29 M G CUT OFF
30 M B CUT OFF
31 CVBS OUT
32 APR THRESHOLD
33 BELL FILTER
34 BANDPASS
35 H POSI OSD
36 V POSI OSD
37 H POSI TEXT
38 V POSI TEXT
39 H POSI (60) Fig. 1-2
2. BASIC ADJUSTMENTS
2-1: CONSTANT VOLTAGE
1. Place the set with Aging Test for more than 5 minutes.
2. Connect the digital voltmeter to TP501.
Set condition is AV MODE without signal.
3.
Adjust the VR501 until the DC voltage is 117 ± 0.5V.
4.
2-2: VCO
1. Place the set with Aging Test for more than 10 minutes.
2. Connect the oscillator (39.5MHz) to TP001.
3. Activate the adjustment mode display of Fig. 1-1 and
press the channel button (13) on the remote control to
select "VCO COARSE".
4. Press the VOL. +/- button on the remote control until
the "OK" appear on the screen. If the "OK" is not
displayed, select the "+" side on the changed from "+"
to "-".
5. Press the Page UP button once to set to "VCO FINE"
mode.
6. Press the VOL. +/- button on the remote control to
select the 5 step down point from the upper limit on the
"OK".
(Example: In case of the "OK" range 30~41, select 36.)
2-3: AGC VOLTAGE
1. Place the set with Aging Test for more than 15 minutes.
Receive the UHF (63 ± 1dB).
2.
3. Connect the digital voltmeter to pin 5 of CP101.
4. Activate the adjustment mode display of Fig. 1-1 and
press the channel button (01) on the remote control to
select "RF AGC".
5. Press the VOL. +/- button on the remote control until the
digital voltmeter is 2.4 ± 0.05V.
2-4: CUT OFF
1. Set condition is AV MODE without signal.
2. Using the remote control, set the brightness and
contrast to normal position.
3. Place the set with Aging Test for more than 15 minutes.
4. Activate the adjustment mode display of Fig. 1-1 and
press the channel button (00) on the remote control to
select "CUT OFF".
5. Adjust the Screen Volume until a dim raster is obtained.
2-5: WHITE BALANCE
NOTE: Adjust after performing CUT OFF adjustment.
1.
Place the set with Aging Test for more than 15 minutes.
2.
Receive the gray scale pattern from the Pattern
Generator.
3. Using the remote control, set the brightness and
contrast to normal position.
4.
Activate the adjustment mode display of Fig. 1-1 and
press the channel button (03) on the remote control to
select "R DRIVE".
5. Press the Page UP/DOWN button on the remote control
to select the "R DRIVE", "G DRIVE", "M R CUTOFF" or
"M G CUTOFF".
6. Adjust the VOL. +/- button on the remote control to
whiten the R DRIVE, G DRIVE, M R CUT OFF, and M G
CUT OFF at each step tone sections equally.
7. Perform the above adjustments 5 and 6 until the white
color is looked like a white.
D-1