The TNG buffer draws power from the TNG PC's USB port and via the serial cable from the PABX. When the PC is shutdown, it can only draw power from the PABX via the serial cable.
To test if the PABX can provide enough power, simply disconnect the USB cable on the buffer side. The WDT light must always flash - this indicates that the software on the buffer is running. If no lights are flashing the buffer does not have enough power to operate.
The buffer has an option to connect a 12Volt DC adaptor for power.
Reasons the PABX does not give enough power could be:
- The serial cable is longer than standard specifications.
- The serial cable is not shielded.