FYI: Your Powercab and SB3/SB3a/SB5 must have the same firmware version to function correctly together
To find the firmware version number: From the regular loco screen on the cab: Press prog / esc 5 times to get to "Set Cmd Station" Press enter The first thing you see is the cmd station version that is what we need to know. Hopefully you see 1.65. That is the most recent version.
If you need to purchase a new chip click here
If you need a manual for version 1.65 click here.