B&K Precision frequency counter 1803

Sometimes using a DMM in the diode position will give the polarity ingo; other times a multimeter in 1K range will be needed for the polarity info. Another way is to take the case off and do xome circuit chasing; at times that bay also give a clue as to the probable input voltage. Ane then again, some meters have the voltage on a case label.

Thanks for the ideas. I took the case off and found an 6- AA cell battery holder inside, and the red lead from the battery holder and the lead from the tip of the power socket were soldered together, so it should be a 9 volt tip positive wall wart. In the meantime, I am using batteries, and it works great.

Thanks.

I opened the case and found a 6 cell AA battery holder inside with the red lead and the socket tip lead soldered together, so it should be a 9 volt tip positive wall wart, I suppose. I wish all my other little mysteries were so easy to solve.