I tested all of the cables that I've used with the MP1550 so far (USB to Nokia 2mm) for resistance. All cables measure less than 1ohm for the negative conductor. The results were different measuring resistance for the positive conductor between the MP1550 Nokia adapter and the other cables. The Tekkeon Nokia adapter measures 5.8ohms resistance while the other cables measure less than 1ohm. I'll order a 5.76ohm resistor from Mouser and use the cable from a Nokia AC-4U charger to see if I can make a better power cable to use with the MP1550.