Sorry, I lost track of this message reply, and back at work today so slow to respond.

This board confuses me a little - there are two 5V supplies indicated to this, yet no specific mention in the manual about how to wire these. More interesting is figure 1 in the pdf (https://www.cnc4pc.com/pub/media/pro...SER_MANUAL.pdf) which shows that the PC parallel interface is isolated from the output drive system. This implies pretty strongly two PSUs.

I asked about measuring the parallel port for two reasons - that Mach3 is driving it properly (generally is, at least the DIR signals) and that it is set to TTL levels - it isn't - it's driving 3.3V which is not ideal, but the image for the chips on the board - ACTs should tolerate this at a logic level. You cannot scavenge 5V directly from this parallel port so with reference to figure 1 I'm wondering how the PC-side interface on the board is powered, versus the "output" side of the board. There is information within figure 1 to suggest "PC +5V" and "PC 0V" which are the two terminals at the top of the board, which in your photo are unconnected.

So, if you will endure me, I'd ask if you can measure the voltage at the PC +5V to PC 0V at the top of the board as shown in the photo. If there is NO measured voltage then I'd ask you to wire the +5V to the main +5V supply, and the 0V to the main 0V. This destroys the galvanic isolation between PC interface and output drivers, but it's a quick and easy test.