55LM4700 (CHASSIS:LA21B) - LG TV Service Manual (repair manual). Page 9

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ADJUSTMENT INSTRUCTION
1. Application Range
This spec. sheet applies to LA21B/C Chassis applied LCD TV 
all models manufactured in TV factory.
2. Specification
(1)  Because  this  is  not  a  hot  chassis,  it  is  not  necessary  to 
use an isolation transformer. However, the use of isolation 
transformer will help protect test instrument.
(2) Adjustment must be done in the correct order. 
(3)  The adjustment must be performed in the circumstance of 
25 ±5 °C of temperature and 65±10% of relative humidity if 
there is no specific designation.
(4)  The  input  voltage  of  the  receiver  must  keep  100~240V, 
50/60Hz.
(5)  At first Worker must turn on the SET by using Power Only 
key.
(6)  The receiver must be operated for about 5 minutes prior to 
the adjustment when module is in the circumstance of over 
15 °C
      In case of keeping module is in the circumstance of 0°C, it 
should be placed in the circumstance of above 15°C for 2 
hours
      In case of keeping module is in the circumstance of below 
-20°C,  it  should  be  placed  in  the  circumstance  of  above 
15°C for 3 hours.
[Caution] 
When  still  image  is  displayed  for  a  period  of  20  minutes  or 
longer (especially where W/B scale is strong.
Digital  pattern  13ch  and/or  Cross  hatch  pattern  09ch),  there 
can some afterimage in the black level area
3. Adjustment items
3.1. Main PCBA Adjustments
(1)  ADC  adjustment:  Component  480i,  1080p  /  RGB-PC 
1080p
(2) EDID download: HDMI and RGB-PC
●  Above  adjustment  items  can  be  also  performed  in  Final 
Assembly  if  needed.  Both  Board-level  and  Final  assembly 
adjustment  items  can  be  check  using  In-Start  Menu  (1.
Adjust  Check).  Component  1080p  and  RGB-PC Adjust  will 
be calculated by 480i adjust value.
3.2. Final assembly adjustment
(1) White Balance adjustment
(2) RS-232C functionality check
(3) Factory Option setting per destination
(4) Shipment mode setting (In-Stop)
(5) GND and HI-POT test
3.3. Appendix
(1) Shipment conditions
(2) Tool option menu
(3) USB Download (S/W Update, Option and Service only)
(4) Preset CH Information
4. MAIN PCBA Adjustments
4.1. ADC Adjustment
4.1.1. Overview
▪  ADC  adjustment  is  needed  to  find  the  optimum  black  level 
and gain in Analog-to-Digital device and to compensate RGB 
deviation.
4.1.2. Equipment & Condition
(1) Protocol: RS-232C
(2) Inner Pattern
- Resolution : 1080p(Comp) / 1024*768(RGB)
- Pattern : Horizontal 100% Color Bar Pattern
- Pattern level : 0.7±0.1 Vp-p
4.1.3. Adjustment
4.1.3.1. Adjustment method
-  Connect  to  Jig  by  using  RS-232,  adjust  Component  and 
RGB
● Manual adj (If needed in Final Assembly)
- Required equipment : Adjustment R/C
- Enter Service Mode by pushing “ADJ” key,
Calibration]
4.1.3.2. Adj. protocol
-  Connect  to  Jig  by  using  RS-232,  adjust  Component  and 
RGB
Protocol CMD 1 CMD 2 Data 1 Data 2
Remark
Enter 
adj 
mode
a
a
00
00
When 
transfer 
the  ‘Mode 
In’,Carry the 
command.
Start 
ADC adj
a
d
00
10
Automatically 
adjustment 
(Use internal 
pattern)
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