Siemens SXG 75 Service Repair Documentation page 57

The voltage seen at the collector of V2000(a) is nominally 2.55V, but can vary between 0.87 and
5.43V with device tolerance.
Resistors R1 and R2 in the LED chain are required to reduce the effects of any mismatch in diode
forward voltage in the two chains. With 270R in each chain, if one chain has a total forward voltage
difference of 0.1V, the difference in currents is 0.1/270= 0.37mA.
LED positions
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 57 of 73