This handy tool lets you know if you decoder has received a programming instruction (or not!) using indicator lights on the circuit board. If your command station has problems reading CV data from some sound decoders that are otherwise working properly (responding to speed and direction commands), the problem may be due to incompatibilities between the electrical requirements of the sound decoder due to the added audio circuitry and the electrical characteristics of the programming track. This unit amplifies programming track signals to levels that work best with SoundTraxx Sound Decoders, and provides short circuit detection and some helpful diagnostics. The PTB-100 is not needed or recommended for use with the Zimo MX1 or the Lenz LVZ100.