If an external speaker is plugged into the 3.5 mm port in the back, can you still hear sound from the speaker on the scanner? I want to use an external speaker in my garage but also have sound at the scanner.
There's a mechanical swith in the jack that breaks the connection to the internal speaker.
You could open up the scanner and solder a wire to the jack so it will never break that connection,
or try inserting the plug gently until you feel a resistance, then the switch never engage and the tip of the plug makes a connection in parallell with the inner speaker.