LG NC55AA Diagram
- 1 -
BLOCK DIAGRM
TUNER
HOT
COLD
TU100
IC2
D801
IC301
IC801
RL801
D/G
COIL
IC1
PA1
5V 12V 33V
LOCK
CLOCK
DATA
CS
35
3
1
2
5
39 41
SDA/SCL
R, G, B, Ys
Q806
Q10
Q401
Q402
1877
H. D. T
Q805
TMP67CC31
IC501
8
9
50
51
45
46
44
48
T402
FBT
1
3
40
34
6
21
23 28
LA7674
SMPS TRANS
TX
IC601
PRE-AMP
EEPROM
12V
R-Y, B-Y, G-Y
5V
24V
180V
STR50092K
PWR
Q11
FBP
FROM FBT
H.Vcc of
IC501
AFT
HV
Z101
VIF
SIF
VCO
AFT
SHARP
BRI
COLOR
TINT
CONT
PRE-AMP.
Q102
SIF-IN
DET-OUT
SFE4.5
TPS4.5
SP
AUDIO IN VIDEO IN
2 12
IC602
CPT
1 4
T403
-Y
TDA
2006
IC202
Q208
Q603
3
2
9
5
6
10
HT
24V
12V
FBP
B+
COL
CPT
TO IC1
TO CPT
TO T403
CPT
JA001
PCB
13
26
D/G
3
1
6
5
8
ADJUSTMENT INSTRUCTION
These instructions are applied to only NC-5AA chassis.
Notes
1.So this is a hot chassis, you must be careful, and be caution
not to touch 1st and 2nd concurrently.
2.Adjustment must be done in the correct order.
3.Power supply of a SET which is adjusted is 100~240V
A.C./50~60Hz.
4.The receiver must be operated for about 30 minutes proir to
the adjustment.
CONTENTS
1) VIF, AFT and SIF Adjustment
2) Sound Multiplex Adjustment
3) FOCUS Adjustment
4) AGC Adjustment
4)-1 Picture AGC Adjustment
5) V-Size and V-Center Adjustment
6) Horizontal Size, Center and Side Pincushion Adjustment
7) Purity and Convergence Adjustment
8) White Balance Adjustment
9) SUB-Bright Adjustment
10) Vertical Center Adjustment
11) Horizontal Center Adjustment
1. VCO and AFT Adjustment
This Adjustment must be applied only to PCB Assy.
1.1. Necessary Instruments
1) Sweamer Generator : can sweep 35MHz~55MHz(over
120dBu)
2) PLUG in Unit : With PIF(45.75MHz), SIF(41.25MHz) Marker
3) Alignment Scope : X-Y mode, 10mV~20V Variable
4) D.C. Power Supply : 0~12V Variable
5) D.C. Power Supply : 13.5V±0.2V (over 300mA)
6) Digital Multimeter
1.2. Preliminary Steps
1) Connect the output of Sweamer Generator like <Fig 1>.
Here, set the output of Sweamer Gen. to 100±5dBu.
POWER
SUPPLY
-
TUNER
IF
SWEEMAR
GENERATOR
+
ALIGNMENT
SCOPE
TP2
+
SAW
FILTER
470/0.5W
7.5V
TP11
+
C122
2
C508
8
9
IC501
LA7674
11
14
R591
TP12
<Figure 1>
L501
VCO COIL
51
50
47
R520
46
C521
45
44
R518
TP4
R507
L506
AFT COIL
9V
Q503
R517
L503
Z502
TP3
L502
12.5V
+
POWER
-
SUPPLY
D502
+B
2) Connect H.Scope and Pulse output of Sweamer Generator
to H.Input and Marker input of Alignment Scope,
respectively.
3) Apply AGC Voltage(D.C.) to TP11 of IC201.(7.5±0.05V)
4) Apply B+ of IC201 to TP12 of R591.(12.0±0.1V)
5) Set VR526(AGC Adjustment) to mechanical center.
1.3. Adjustment
A. VCO
1) Set the vertical range of Alignment Scope to 1V/DIV and
CAL position, and, by applying D.C. 0~9V, do DC
Calibration to place D.C 4.5V point of waveform to center of
Screen.
2) Connect the Input terminal of Alignment Scope to
TP3(Video Detection Output), and set Vertical Variable
Switch to CAL position.
3) Apply AGC Voltage to TP11 of IC201 through 470§to be
7.5±0.05V
4) Adjust L501 so that BEAT appears on 45.75MHz Marker
like <Fig 2> If not, adjust again after attenuating output 10
~20dBu.
42.75
B. AFT
1) Connect the Input of Alignment Scope to TP4 with keeping
DC voltage of 2pin of IC201.
2) Keep the output of Sweamer Generator 100±5dBu.
3) Adjust L506 so that waveform of Alignment Scope to be
that of <Fig 3>.
4) Adjust Vertical Volume of Alignment Scope to place DC
level of waveform to center (4.5V) and 45.75MHz Marker to
7.5V¡0.5V.
9V
8V
AFT
0V
2. SIF Adjustment
VCO
2.1. Necessary Instruments
1) Sweamer Generator : can sweep 3~6MHz
2) Plug In Unit : with 4.5MHz Marker
3) Alignment Scope : X-Y mode(can measurable 10mV~
20Vp-p)
4) DC Power Supply : 13.5V, over 300mA
5) DC Power Supply : 0~12V variable
f (MHz)
45.0 47.25
45.75MHz
(Turn L105 so that the position of Beat
is same with 45.75MHz Marker)
<Figure 2>
45.75 MARKER
<Figure 3>
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