Electrical Adjustments - Toshiba VTD1551 Service Manual

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. Pattern Generator
On-Screen Display Adjustment
1. Set the volume level to minimum.
2. Press the VOL. DOWN button on the set and the
channel button (9) on the remote control for more than
2 seconds to display 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
3. Use the Channel UP/DOWN button or Channel button
(0-9) on the remote control to select the options shown
in Fig. 1-2.
4. Press the MENU button on the remote control to end
the adjustments.

ELECTRICAL ADJUSTMENTS

VCO Status -
129
XXX
57
125
57
42
Fig. 1-1
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 ---
16 ---
17 BRIGHT CENT
18 BRIGHT MAX
19 BRIGHT MIN
2. BASIC ADJUSTMENTS
2-1: CONSTANT VOLTAGE
1. Connect the digital voltmeter to TP401.
2. Set condition is AV MODE without signal.
3. Using the remote control, set the brightness and contrast
to normal position.
Adjust the VR3801 until the digital voltmeter is 135 ± 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 TP101.
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 LEFT/RIGHT 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 CH UP button once to set to "VCO FINE"
mode.
6. Press the LEFT/RIGHT 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" point 41, select 36.)
2-3: RF AGC
1. Receive the UHF (63dB).
2. Place the set with Aging Test for more than 15 minutes.
3. Connect the digital voltmeter between the pin 5 of
CP101 and the pin 1 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 LEFT/RIGHT button on the remote control
until the digital voltmeter is 2.4 ± 0.05V.
D-1
NO. FUNCTION
20 TINT
21 SHARP
22 CONT CENT
23 CONT MAX
24 CONT 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 THR
33 BELL FILTER
34 BANDPASS
35 H POSI OSD
36 V POSI OSD
37 H POSI TXT
38 V POSI TXT
39 H POSI 60
Fig. 1-2