45XP voltage divider connection

[ButcherRaceEngineering]

I have recently started to read 0v on my table so the torch as expected rises when cutting as it is trying to achieve a set voltage of 120 for example. I have checked the reading from pins 5 and 6 that supply the table. I am still getting 0v. I have checked the resistance of pins 5 and 6 on the connection cable between the cutter and the table and these are good. When checking resistance on the main board from the raw arc points to the take off for the divider board the - side the reading isn’t quite right. The positive side is good. I am assuming just like when doing a retrofit that I could wire the voltage divider straight to the acre terminals where the raw arc voltage points are if there is a problem with the original connection point?
I am going to run a test as soon as I get chance to see if I get a voltage direct from the raw arc points.

[robertspark]

if you search for the service manual there is a rough schematic in the rear that will show you the circuit and then you can trace it out on the PCB (bottom LHS when cover removed)

ensure you allow time for the capacitors to discharge or you'll get a real nasty surprise (front of the service manual, safety instructions)

[tcaudle]

Is proably NOT the voltage divider card itself. The resistance taht matters is the one between pins 5 and 6. If the raw voltage was 0 you would get not arc....none.

The most common failure on the Hypertherm voltage divider is the Primary divider that is on the Main Board,not the voltage divider card. Its does a division and has a filter cap at the high volte side. Most common failure is the cap that is the filter . It shorts and causes zero volts . it zero BEFORE it ever gets to the secondary voltage divider card ). You can find any of tis with the unit off and just the ohmmeter.

[jimcolt]

Tom's (tcaudle) advice is correct. Follow his recommendation to troubleshoot zero voltage output at pins 5 and 6 on the plasma. If zero volts it can be caused by a bad voltage divider inside the Powermax, or, more common, a bad main power board inside the Powermax (Power board sends voltage signal to voltage divider, located inside Powermax. Jim Colt

[ButcherRaceEngineering]

Many thanks for the replies. I have measured the raw arc voltage when cutting at the points on the main board and when cutting 3mm with fine cut tips the voltage read roughly 70. The torch was very close to the plate as the initial touch off switch was out so this seems correct.

If it’s the main voltage divider board, can these be replaced or is it a case of a new main board?

[tcaudle]

Is not the voltage . Its the dividor he main board . The main board is not a replacement part that I am aware of. You either have to take it to an authorized repair venter and THEY will replace the main board and IK recommend you be sitting down when you get the bill.

The other option is to replace it with a raw voltage divider. You THC vendor should have something you can use to read raw volts .

[ButcherRaceEngineering]

I have been advised if this is the case it may be worth buying a new 45xp with hand torch and cpc port and then selling the old hypertherm unit to cover some of the cost as a hand unit. This way the whole machine will be brand new and have a 3 year warranty.

An alternate THC may also be an option but the main table I use has everything integrated with the main drivers etc.

[djreiswig]

A voltage divider isn't all that complicated. Basically just some resistors that step down the raw voltage to something safer. As long as you have the correct ratio, it should work fine with your THC.

[ButcherRaceEngineering]

Of course that’s a much better option. After some digging I have found this:
https://www.ampmechanic.com/voltagedividerlite
I am thinking of disconnecting the original hypertherm voltage divider from the main board, wiring this straight to the raw arc voltage points on the main board. Then connecting the other side of this to pins 5 and 6 on the cpc port so everything external to the plasma connects as normal. Can any one see any issues with that?

[djreiswig]

That should work. If you search the forum, I believe you could find instructions to build a much less expensive option with a few easily sourced resistors.

Maybe this:
https://www.plasmaspider.com/viewtopic. ... 91#p200191