I always double check the PCB paint, with the position of capacitor that was soldered in there and the meaning of it's polarity markings. See the bellow wikipedia picture text: In non solid electrolytic capacitors the line/mark in the capacitor identifies the negative - capacitor side. In solid electrolytic capacitors the line/mark in the capacitor identifies the positive + side. This wikipedia picture is worth a thousand words: https://en.wikipedia.org/wiki/Capacitor_types#Polarity_marking So in the photo I posted the white line in the stock solid capacitor is the positive (+) PCB pad. Note: With circuit power on, we can also use a multimeter to find the voltage polarity at the caps legs.