HP L1740 
38 
14. Check List after replacing LCD Main Board     
   Check if white-balance is within the specs after replacing Main board and panel,then re-writing DDC is 
necessary.
 
14.1 Check white-balance   
The white-balance value for each common color temperature:   
9300 º K: x=283± 20 ;  y = 297± 20;  
6500K: x = 313± 20 ;  y = 329 ± 20; 
sRGB: x = 313± 20 ;  y = 329 ± 20; 
The color temperature value above must be up to the situation of x<y. The value of Y should be 
confirmed according to different customers. 15 ”LCD is commonly 180±20cd/cm
2
(Center)and 17” LCD is 
required to be larger than 200cd/cm
2
 (Center). The exact brightness values are confirmed by the 
checking-regulations of different customers and different models.     
 
14.2 Steps for writing DDC: 
 
Re-programming Analog DDC IC 
Step 1: After initialize alignment box, connecting all cables and box as shown in Fig. 10. 
 
 
 
Step 2: Read DDC data from monitor 
1. Click
  icon as shown in Fig. 11 from the tool bar to bring up the Channels "Configuration Setup" windows as 
shown in Fig. 11.