If you are using the supplied LCD :
High-power Backlight LCD (i.e. LED array)
If you are using a high-power backlight LCD that requires 250mA or more, then you should put a shunt in
JBL in the “12V†position. It is labelled “12V†but it actually will be whatever voltage is coming into the
base PCB, i.e. the input to the 7809 voltage regulator. Most often this is going to be 12V-14V. Put a shunt
in JR4 to increase current. Turn brightness trimpot to approximately 2 o'clock, this gives the optimal
current for a high-power backlight LCD being supplied by 12V and is considered “safeâ€. Experienced
builders can try connecting a 2-pin SIL connector to JBL and measuring the actual current passing
through JBL pins (i.e. between 12V and the backlight circuit).