Hello Pointman,
Sorry you did not leave a name.
You need a wallbox transformer that gives an output of 30 volts AC.
The 70 volt you refer too on your jukebox is the two 70 volt line connections that is used for connecting speakers on very long runs, this uses 70 volt line transformers at set wattages fir use in toilet and stairwell speakers.
Regards
Alan Hood
ami-man
UK