For an Anet A8, viewed from the top of the hot bed, with the pins facing away from you, and numbering the pins 1-6 from the left.
Pin 1 +ve red wire
Pin 2 +ve not connected
Pin 3 thermistor green wire
Pin 4 thermistor blue wire
Pin 5 -ve not connected
Pin 6 -ve black wire
On the motherboard the rightmost of the two hot bed supply pins is +ve and the leftmost -ve.
If you are having problems with the bed not heating then check the resistance reading across pins 3 and 4. It should read 100k ohm. If pin3 to pin4 reads open circuit then measure directly across the thermistor, it should read 100k ohm. If it reads open circuit then the thermistor is faulty. If it reads OK then one of the two very fine printed tracks has a gap (break) in it. This latter was the case with mine.
