There are known issues with the CPC port on the Everlast machines. I strongly recommend that you wire it up to raw voltage. Beyond that there are only a few reasons why you would see low or no arc voltage show up in FireControl, and they can all be narrowed in on by following this troubleshooting guide: LS-THC Arc Voltage Troubleshooting Guide
There are about 1300 of these machines running in the field- almost all of them with THC. It’s possible that one of the electronic components is faulty, but 9/10 its usually wired up incorrectly. Not saying you have wired it incorrectly, just that its a common problem.