I am looking for assistance to replace the battery in a Panasonic RD55 car radio - I need to identify which connectors on the PC board are +ve and -ve. There are two connectors - 1 circular and the other is a "larger" slot. Panasonic used to supply the batteries pre assembled with the connectors so it was almost idiot proof. This is no longer the case and this idiot cannot remember which side is positive and which is negative.