DSO138 Power Issue Possibly Jack Connection

[supernaut5150]

I have no trace -and have isolated the issue to a power issue. Specifically the connection to the power. I can bypass the plug and connect to a 9v battery no problem.
When I connect to the plug with a jack from a 9 volt power supply nothing happens.
I have checked the power supply with other devices and it works fine. The power supply is a 9 volt 300mA regulated power supply.
Seems to me that the issue is either with the jack on either the male on the power supply or the female on the scope.
I am not certain how to diagnose.
Thanks

[adr]

Are you sure the pack is center post positive?

[supernaut5150]

I am not certain but will try and find out. This is exactly the sort of direction I was looking for. Thanks!

[supernaut5150]

it has a center negative polarity. Thanks for the help!