Service Adjustments - JVC AV-20FD24 Service Manual

SERVICE ADJUSTMENTS
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 (YG6260M) 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 Transis-
tor).
Prepare the following measurement tools for electrical adjust-
ments.
1. Oscilloscope
2. Digital Voltmeter
3. AC Voltmeter
4. Pattern Generator
5. Multi-Sound Signal Generator
On-Screen Display Adjustment
1. Set the VOLUME to minimum.
2. 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.
Function
01 OSD
Step No.
3. Use the Channel UP/DOWN button or Channel button (1-0) 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
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Fig. 1-1
No. 52133
NO. FUNCTION
01 OSD H
02 OSD CONTRAST
03 CUT OFF
04 H POSITION
05 H BLK L
06 H BLK R
07 V SIZE
08 V POSITION
09 V LINEARITY
10 V S CORRECTION
11 V COMP
12 R CUT OFF
13 G CUT OFF
14 B CUT OFF
15 R DRIVE
16 G DRIVE
17 B DRIVE
18 BRIGHTNESS(CENT.)
19 BRIGHTNESS(MAX)
20 BRIGHTNESS(MIN)
21 CONTRAST(CENT.)
22 CONTRAST(MAX)
23 CONTRAST(MIN)
24 COLOR(CENT.)
25 COLOR(MAX)
26 COLOR(MIN)
27 TINT
28 SHARPNESS
29 SUB BIAS
30 BRI. AV(CENT.)
31 BRI. AV(MAX)
32 BRI. AV(MIN)
33 CONT. AV(CENT.)
34 CONT. AV(MAX)
2. BASIC ADJUSTMENTS
2-1: CONSTANT VOLTAGE
1. Set condition is AV MODE without signal.
2. Using the remote control, set the brightness and contrast to
normal position.
3. Connect the digital voltmeter to TP401.
4. Adjust the VR3800 until the digital voltmeter is 114 ± 0.5V.
2-2: FOCUS
1. Receive the monoscope pattern.
2. Turn the Focus Volume fully counterclockwise once.
3. Adjust the Focus Volume until picture is distinct.
2-3: CUT OFF
1. Adjust the unit to the following settings.
R DRIVE=3F, G DRIVE=07, B DRIVE=3F, R CUT OFF=7F, G
CUT OFF=7F, B CUT OFF=7F
2. Place the set with Aging Test for more than 15 minutes.
3. Set condition is AV MODE without signal.
4. Using the remote control, set the brightness and contrast to
normal position.
5. Activate the adjustment mode display of Fig. 1-1 and press the
channel button (03) on the remote control to select "CUT OFF".
6. Adjust the Screen Volume until a dim raster is obtained.
AV-20FD24
NO. FUNCTION
35 CONT. AV(MIN)
36 COL. AV(CENT.)
37 COL. AV(MAX)
38 COL. AV(MIN)
39 TINT AV
40 SHARPNESS AV
41 SUB BIAS
42 BRI. DVD(CENT.)
43 BRI. DVD(MAX)
44 BRI. DVD(MIN)
45 CONT. DVD(CENT.)
46 CONT. DVD(MAX)
47 CONT. DVD(MIN)
48 COL. DVD(CENT.)
49 COL. DVD(MAX)
50 COL. DVD(MIN)
51 TINT DVD
52 SHARPNESS DVD
53 SUB BIAS
54 BRI. GAME(CENT.)
55 BRI. GAME(MAX)
56 BRI. GAME(MIN)
57 CONT. GAME(CENT.)
58 CONT. GAME(MAX)
59 CONT. GAME(MIN)
60 SUB BIAS
61 TUNING V MUTE
62 POWER ON V MUTE
63 INPUT LEVEL
64 SEPARATION L
65 SEPARATION H
66 X-RAY TEST
67 H STOP
68 H FREQ
Fig. 1-2
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