Sick and tired of my Tranzport being dead more than alive I finally set out to power it from a transformer.
The 4 AA batteries are in series yealding 6.2 Volts with fresh ones. This means a 5V DC transformer for phone charging will act like mid life batteries.
It is easy to see where to hook up the pos and neg transformer wires to the battery clips as the red wire is pos and the black negative inside the tranzport that run from the battery holder to the main board. The tranzport is held together with 4 star screws two visible on the bottom, two inside the battery holder. Use a DVM to be absolutely certain of which lead from the transformer in pos and neg then solder them to the battery clip underside where the red and black wires to the main board terminate.
 
That's it. If you do this correctly, you will see the tranzport come to life when plugged into a wall socket and say batteries are about 3/4 good.
 
 

IDK man. I ain't no electrimical engineeriner but that sounds like it could easily end in tears (and perhaps even fire).
 
ampfixer would likely have a good answer on this...
 
I seem to recall from when I was a kid there were special wall adapters you could use in these situations (as in using the existing battery contacts and "dummy" batteries when necessary).
 

Running a unit at less than optimum power level consistently isn't always good for it. There seems to be very little info out there for this one so adapt at your own risk.
 
Voltages should match as close as possible. Higher volts will ruin it and lower volts could hinder operation.
 
An adapter's amperage can be higher than the unit's rating with no worries, but a lower amperage will not power the unit properly or at all.
 
An option might be to use rechargables or long lasting batteries like Energizer's Ultimate Lithium 9x's, then wire in a switch to prevent any draw when not used.
 
Another is to wire in a female power jack that will accept the adapter's plug.
 
Instructable