Why is the display board backlight of fuel dispenser powered on, while the mainboard is not powered on?

Possible fault sources:

a.The internal power supply of fuel dispenser fails to output 5VDC and 12VDC voltage to the mainboard

b.Mainboard is damaged

c.Power supply cable of mainboard is loosened or is poorly contacted

Recommended solutions:

a.Check whether or not the power panel outputs 5VDC and 12VDC voltage; if not, replace the power panel

b.Maintain or replace the mainboard

c.Check whether the power cord of mainboard is normal or not