Thermal Dynamics Pak Master 50 Plasma Cutter Won't Cut

[dinan]

Hello,

I recently purchased a Thermal Dynamics Pak Master 50 from an auction. I took a gamble on it since it had a 460v 3 phase plug on it, and the auction site didn't have any 3 phase outlets. I bought a 220v 1 phase plug for my garage, and tried it. Nothing happened. It turned out the pilot light was bad. Apparently, if the pilot light is bad, then the rest of the unit won't function. After replacing the pilot light, the unit started right up.

The problem now, is that it won't produce an arc for more than a split second. The strange thing is that I can see an arc at the torch head for a split second, but I cannot see any spark at the spark gap whatsoever. The diagnostic procedure in the troubleshooting manual seems to be pointing to the high frequency/spark gap transformer or the torch assembly. I am getting 120 volts to the high frequency/spark gap transformer. I am also getting approximately 5 ohms of resistance on the primary side of it. I have been unable to check the secondary side because of its location.

Does anyone have any ideas as to what I should check, or what most likely is wrong?

Thanks!

[OldSkull]

Here a link for the manuel so you can check the input wiring installation diagram and compare with what's done on your unit to work on single phase, wish this help.

http://www.thermadyne.com/IM_Uploads/DocLib_1578_0-2344%20PAK%20MASTER%2050.pdf

[dinan]

Hello,

Perhaps I should be more direct. It is wired properly for 220V 1 phase currently.

Everything on the unit seems to work fine, except for the fact that the spark gap doesn't seem to have any spark, and the torch only has an arc for a split second.

The troubleshooting manual on the Thermal Dynamics website is pointing in the direction of either the high frequency / spark gap transformer being bad, or the torch assembly being bad.

I am unsure as to how to test the transformer. It has a 120VAC input, and a 6,000VAC output. I know that I don't have any test equipment that can go that high to test the secondary side, AKA the output side, of the transformer for voltage. I have tested the primary / input side for resistance, and proper input voltage, but as of yet I haven't been able to disassemble the plasma cutter enough to test the secondary side.

The list price on the transformer alone is over $400! So you can understand why I'm reluctant to buy it unless I know for a fact that the transformer is bad.

Is there any other things I should look at? I have done a lot of low voltage electronic repair, but when it comes to high frequency, high voltage, along with high amperage, I am pretty much lost. Could a safety interlock be bad? What about an interlock relay? Something in one of the driver circuits?

Why do I get only a single split second spark at the torch, and no visable spark at the spark gap whatsoever? Does anyone have and ideas or hunches?

Thanks!

[jimcolt]

You can call T-D tech service....they can walk you through troubleshooting.

If you are seeing a momentary spark at the torch...then the high voltage transformer in the high frequency circuit is ok. Could be some bad capacitors in that circuit.....a bad pilot arc relay, incorrect consumables in the torch or a shorted torch body.....among other things.


Jim Colt Hypertherm



Hello,

Perhaps I should be more direct. It is wired properly for 220V 1 phase currently.

Everything on the unit seems to work fine, except for the fact that the spark gap doesn't seem to have any spark, and the torch only has an arc for a split second.

The troubleshooting manual on the Thermal Dynamics website is pointing in the direction of either the high frequency / spark gap transformer being bad, or the torch assembly being bad.

I am unsure as to how to test the transformer. It has a 120VAC input, and a 6,000VAC output. I know that I don't have any test equipment that can go that high to test the secondary side, AKA the output side, of the transformer for voltage. I have tested the primary / input side for resistance, and proper input voltage, but as of yet I haven't been able to disassemble the plasma cutter enough to test the secondary side.

The list price on the transformer alone is over $400! So you can understand why I'm reluctant to buy it unless I know for a fact that the transformer is bad.

Is there any other things I should look at? I have done a lot of low voltage electronic repair, but when it comes to high frequency, high voltage, along with high amperage, I am pretty much lost. Could a safety interlock be bad? What about an interlock relay? Something in one of the driver circuits?

Why do I get only a single split second spark at the torch, and no visable spark at the spark gap whatsoever? Does anyone have and ideas or hunches?

Thanks!

[ccawgc]

Start at your torch, do you have the right nozzle and is it assembled correctly?
If a one torch, check the start cartridge and make sure the plunger moves and the contact to the nozzle is clean. Then check the o-ring at the top of the head make sure it is not covering the holes in the wrong groove. Two grooves side by side.
Check gas pressure setting,65 to 70 psi with air flowing. Air turned up high will blow out arc. Using a 60 amp nozzle on a 35 amp machine will also do the same thing. You just get a pop at the torch. It may cut if placed down on the metal when trigger is pulled. after that we need to go inside. The coupling transformer almost never goes bad. Pilot relay could be bad.