Uniden BC350A won’t turn on when connected to 12V transformer

[MURSman]

Hi all, I’m new to the site and I have some questions that I best should ask here.

I have a BC350A scanner mounted in a remote location, and I would like to power it off of a 12V step down transformer, the problem is I can’t get the scanner to turn on, despite everything being wired up correctly.

When powered off the regular wall connector, it works fine, but the location it’s at does not have a receptacle for plugging in the wall connector, so I have to use the outputs on the transformer.

Is there some type of switch or fuse preventing it from turning on or something?

 

[RMason]

Is the barrel connector the right size? Does it fit tightly in the scanner?
Does the scanner still work with the wall wart?
You did confirm with your measurements that the center of the connector is the right polarity (i. e. +12V)?