Wiring for 4 contactors instead of 6 - PRT Alpha

[harryball]

I have a 2006 PRT Alpha, it came with 6 contactors in it (the big relays) and I've only ever used 4. It was the IWF show floor model that had 2 spindles. I had planned on running 2 spindles but quickly learned that was too much mass on the gantry for the speeds I run. Anyway, I need to replace the relays as 1 and 2 are failing so the plan was to use 2 new relays for 1,2 and move 5,6 (no load on them) to position 3,4.

However... 1) what is actually wired in the box does not exactly match the provided wiring diagram and 2) the diagrams only show the full 6 contactors wired not explaining how to route the control wiring if you only have 4 contactors.

Anyone have a wiring diagram for 4 contactors only?


To be specific.
Rx3B and Rx7B interact between contactors 5/6 and 1/2

If I remove 5/6 do I route Rx8 and Rx2 directly to 1/2

yeah, I'm confused here, any help would be appreciated.

[Gary Campbell]

Rob...
Left you a message, give me a call.

[harryball]

Thanks for the offline help from both Shopbot and others. Got it up and running.

The answer is... and I don't know if I can explain this, the path through the relays for the RX wires really doesn't matter so long as each column is kept correct. In my case they were wired in reverse order than the wiring diagram I had on hand and that just confused me. Once I got that sorted out the answer was simple. Leave the feed wires (wires that go somewhere other than to a neighboring relay) disconnected and safed off or remove them. For the wires that go "through" 5/6, simply connect them together to continue the circuit to the 1/2 relays.

So, did all that, powered it up and it works. All this just because I'm too cheap to by $240 worth of contactors to sit in there and do nothing. Can you blame me? :-)

[harryball]

Rob...
Left you a message, give me a call.

Thanks Gary, got the message about the time I realized just how simple this was. I made this harder than it should have been, but I didn't want to turn on the power to a fireworks show either!