THCAD 10 / 7i76 wiring

Hey new to all this and just need anyone with experience wiring a mesa thcad-10 and 7i76 to the plasma cutter, got this diagram of what i could figure out and just want to confirm if this would be correct or if anything is wrong with this picture, Thanks

1. The THCAD 5V power should come from 7I76 TB3 pins 6 and 9

2. Normally "START" requires a contact closure.
This can be done by using the spindle enable pins
(TB4 pins 5 and 6)
You will need to determine the polarity of the "START"
signals with a voltmeter before wiring

So i tested the start pins and got 5v positive on pin 4 and negative on pin 3, also did continuity but the positive and negative reverse directions? not a huge expert on that.

I would assume that this being the case i would wire pin 3 start to "TB4 pin 5" and then pin 4 start to "TB4 pin 6" ?

luftlupus wrote:

So i tested the start pins and got 5v positive on pin 4 and negative on pin 3, also did continuity but the positive and negative reverse directions? not a huge expert on that.

Continuity is not really meaningful if there is a voltage present.

luftlupus wrote:

I would assume that this being the case i would wire pin 3 start to "TB4 pin 5" and then pin 4 start to "TB4 pin 6" ?

Yes

Thanks for the help much appreciated this is my final draw up on the wiring, I also found the machine is 20:1 on the divider also. Cheers

I'm just a bit confused about the + 12 v power supply on pin 12. Is that what you are using for 7i76e field power? To me this should be connected to field power +24v. There is no need for an extra power supply.

Also I would suggest that you connect a 1K 1W resistor to your ArcOK input to Field power ground -24V
This will ensure that sufficient current passes through the internal relay in the plasma cutter so the current draw exceeds the minimum required current so the contacts don't oxidise and cause intermittent behaviour. I got caught with this with my Everlast and still do it the same way on my Thermal Dynamics. It could save many hours of frustration.

Yes the 12v is field power, also i am learning as i go with this and adjusted the drawing to be a bit clearer is this what you meant with putting the resistor in the ArcOK line? Thanks

Yes, you might need to revisit the resistor value as its specced for 24v field power. It probably needs to cause say 100 mA current to flow and be rated to handle the power (in watts).

Normally, we would use 24 v field power which would give better noise immunity (eg a lot more noise required to alter the signal). $40 for say a Meanwell 2 amp power supply is not really significant.

Thanks for the advise, i will change the field power to 24v and add in the resistor.

Hello,
Can you show me which one the voltage div and arc ok on chinese plasma cutter has pilot arc (such as tosense plasma cut50 : www.aliexpress.com/item/4001168150005.ht...02_,searchweb201603_) ?