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Toshiba 20AF43 Manuale di servizio
1.
BEFORE MAKING ELECTRICAL
ADJUSTMENTS
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. Multi-sound Generator
4. 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 1 second to
appear the adjustment mode on the screen as shown in
Fig. 1-1.
00 OSD
2.
Use the Channel UP/DOWN button or Channel button (0-
9) 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
NO.
00
OSD H
13
01
CUT OFF
14
02
H.VCO
15
03
H.PHASE
16
04
AFC GAIN
17
05
V.SHIFT
18
06
H.SIZE
19
07
V.SIZE
20
08
V.LINEARITY
21
09
VS CORRECTION
22
10
R DRIVE
23
11
B DRIVE
24
12
R BIAS
25

ELECTRICAL ADJUSTMENTS

TV
34
FUNCTION
NO.
FUNCTION
G BIAS
26
CB DELAY FINE
B BIAS
27
CR DELAY FINE
BRIGHT MAX
28
CB PEDESTAL ADJ
BRIGHT CENT
29
CR PEDESTAL ADJ
BRIGHT MIN
30
E/W PARABOLA
CONTRAST MAX
31.
E/W CORNER
CONTRAST CENT
32.
E/W TRAPEZIUM
CONTRAST MIN
33.
LEVEL
COLOR MAX
34.
SEPARATION 1
COLOR CENT
35.
SEPARATION 2
COLOR MIN
TINT
SHARPNESS

2. BASIC ADJUSTMENTS

2-1: CONSTANT VOLTAGE
1.
Place the set with Aging Test for more than 5 minutes.
2.
Set condition is AV MODE without signal.
3.
Using the remote control, set the brightness and contrast
to normal position.
4.
Connect the digital voltmeter to the TP003.
Adjust the VR502 until the digital voltmeter is 115 ± 1V.
5.
2-2: CUT OFF
1.
Place the set with Aging Test for more than 15 minutes.
2.
Activate the adjustment mode display of Fig. 1-1 and
press the channel button (01) on the remote control to
select "CUT OFF".
3.
Adjust the Screen Volume until a dim raster is obtained.
2-3: WHITE BALANCE
NOTE: Adjust after performing CUT OFF adjustment.
1.
Place the set with Aging Test for more than 10 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 (10) on the remote control to
select "R. DRIVE".
5.
Press the CH. UP/DOWN button on the remote control to
select the "R. BIAS", "G. BIAS", "B. BIAS", "R. DRIVE" or
"B. DRIVE".
6.
Adjust the VOL. UP/DOWN button on the remote control
to whiten the R. BIAS, G. BIAS, B. BIAS, R. DRIVE, and
B. DRIVE at each step tone sections equally.
7.
Perform the above adjustments 5 and 6 until the white
color is looked like a white.
2-4: FOCUS
1.
Receive a broadcast.
2.
Turn the Focus Volume fully counterclockwise once.
3.
Adjust the Focus Volume until picture is distinct.
Fig. 1-1
2-5: HORIZONTAL POSITION
1.
Receive the monoscope pattern.
2.
Using the remote control, set the brightness and contrast
to normal position.
3.
Activate the adjustment mode display of Fig. 1-1 and
press the channel button (03) on the remote control to
select "H.PHAS".
4.
Press the VOL. UP/DOWN button on the remote control
until the SHIFT quantity of the OVER SCAN on right and
left becomes minimum.
2-6: VERTICAL POSITION
1.
Receive the monoscope pattern.
2.
Using the remote control, set the brightness and contrast
to normal position.
3.
Check if the step No. V. SHIFT is "02".
Adjust the VR401 until the horizontal line becomes fit to
4.
Fig. 1-2
the notch of the shadow mask.
D-1