Powermax 45 Voltage Divider Problem

[chattacuda]

I think I have a problem with the control board on my Powermax 45 most likely caused by a lightning strike nearby. Is there any other possible cause I may be missing? Is there anything I can do to harden the system again lightening strike damage? The Powermax was unplugged at the time this happened and I can only assume it must have got in thru the control wiring from the CandCNc or the torch head/ground.

I assume I had a close in lighting strike at my shop as I had three pieces of electronics fail at the same time; an electronic thermostat, a UBOB board on the CandCNC bladerunner box, and a powers supply to my laptop. After getting the UBOB board swapped ( thanks to Tom for helping figure that one out and a quick replacement board delivery), I fired up the plasma table and made a test cut, which cut fine. The problem is the torch volts reading on Mach 3, with the the setpoint voltage at 200, starts off at about 37 to pierce, then drops to about 29 with the torch height at 0.06 for the rest of the cut. DTHC is on and does not move the torch to try and get to setpoint. My test cut was on some 0.25" HR and it cut fine. Just no THC and wrong torch volts. I went thru all the checks on the CandCNC ( setpoint voltage check at 126 on the THC sensor PWM and DTHC at 100 and 150 with appropriate torch up and torch down response). I finally checked the voltage output on the stereo plug coming out of the PM45 and in read 0.75v with the torch fired in air, which is a problem. I pulled the front cover off the PM45 and the error light LED glows solid when torch is stopped.

I am taking the PM45 to an authorized repair shop this morning

[SeanP]

I had that happen to me after a storm, mine was still plugged in though, full credit to hypertherm though it was still under warranty and they put in a new board, they did say it was unlikely to have been lightning though, I didn't argue

[jimcolt]

The way to check the voltage divider output is to cut a part with the torch at a fixed height...then read the voltage divided output voltage on pins 5 and 6 at the CPC receptacle on the Powermax45. This will read 1/50th of the actual arc voltage....so pins 5 to 6 will be between 1.5 and 3 volts dc while cutting. A reading while firing a pilot arc is mostly irrelevant.....as you have not created a work path through the work clamp.

On the Powermax45...if the voltage divider is bad, it is likely a failure on the main power board. Because that is costly...you could use the voltage divider module from CandCNC.com....might be a better solution.

I would be surprised if a lightning surge would feed back through the CandCNC electronics without causing damage there as well.

Jim Colt Hypertherm

[chattacuda]

Jim, thanks for the quick response. The CandCNC UBOB board was damaged too. I could not get head to move, fire, anything till I replaced that board. That is when I discovered the Plasma Voltage divider problem. Thanks for your suggestion on the RAV board option. I just dropped the PM45 off at the repair center. Will see what they come up with and go from there. Any suggestions on prevention or hardening the machine? Thanks again.

[jimcolt]

Generally unplugging or disconnecting input power is all you should do. One suggestion that may have helped in your case would be to get a good quality office UPS (uninteruptible power supply) that has surge and lightning protection. Plug all your 120 volt items (PC, drive electronics, THC, etc) in this unit....it will provide an extra layer of protection from power line surges and spikes.

I intentionally leave my Plasmacam table with the Powermax85 plugged on and powered up, both Plasma and table....as I am curious as to the effects and damage that could be caused by line anomalies. It has been plugged in for 9 years...and not a single issue. The PC and the Plasmacam 120 volt power is through an office UPS.

Jim Colt

[chattacuda]

I never thought of an UPS as an extra line of protection. I have a supposedly very good surge protector on my CandCNC power supply and my PC but I doubt anything could protect against close in strikes back feeding through a ground, etc. I heard from my Hypertherm repair tech this morning that the control board was bad and he had to order one. He said the factory said to make sure no back feed was coming in on pins 4 and 5 while cutting. Not sure what that meant exactly but will get details from him when I get the machine next week. I will definitely get me a UPS and I am considering adding lighting rods to the top of the shop. So far this has cost me $550 and that does not count the powermax repair.

[chattacuda]

Pickd up the PM45 yesterday morning! Great service and turn around time. Hooked the system up and did a test cut no problems! From now on I will try and remember to unplug everything if a storm is coming through. I plan to order a UPS today as extra precaution based on Jim's advice. The service guy was bragging about Hypertherm's saying he sees very few come cack for repairs!

[jimcolt]

Glad to here you are running again. Jim Colt

[Capstone]

So... I think I have the same issue, but I'm really not sure if it's a problem or not. Sorry for the threadjack, but I guess I really didn't think it was an issue until I read this post.

I've been cutting stuff for a year now, using the CandCNC EtherCUT setup, mostly 16ga MS, using 30amp consuambles, and my voltage readout is a steady 38 and the DTHC operates correctly to the correct cutting height of .02, with minor adjustments made on the fly in MACH. Just this week I actually cut some 3/4" using my 45amp consumables and the readout, with DTHC turned off, was 52?!

I really, really don't want to mess with things and go into diagnostic mode unless there's some kind of long term damage being caused to any of my components or I'm significantly affecting the life/performance of the consumables.

TIA for any insight and advice.

[sphurley]

What jumper setting do you have on the PWM card from CandCNC? The PM45 is fixed at 50:1

[acourtjester]

There is a switch on the back of the PWM for testing one is for the voltage output and when it is switched you should see about 126 volts on the mach screen. The other switch will show as arc OK on when switched. It is in the manual for testing on start up in the installation. If that is correct then as sphurley states maybe the plasma units voltage divider is not set to 50:1. If you see a voltage input change when cutting and the torch moves to follow the 50:1 may be the answer.

[Capstone]

I confirmed that It's set to 50:1. The Voltage readout in MACH, when the PWM is in test mode, says 124 and occasionally flickers up to 125. According to the CandCNC Manual, I'm not supposed to mess with the DTHC II module since it's a BladeRunner AIO Dragon Cut even though it's "out of spec" by 2pts.

I am using a machine torch with the MIC-01 as well, if that's relevant.

Suggestions? Thanks

[acourtjester]

That sound like it's fine (PWM MOD) you may want to contact the hypertherm tech staff on Monday.
The guy I sold my first table to bought a PM-65 and the voltage divider was bad and they replaced it but that was when it was new!!

[sphurley]

If your voltage is that far off, you must never use the DTHC?
If you measure the input to the PWM from the Hypertherm while cutting it should be in the 1-3volt DC range. (1/50 of the arc).
Or put a 1.5volt battery on the PWM input and Mach should read 75volts

[Capstone]

I use the DTHC IV all the time on 16GA, and the DRO moves the Z as the voltage changes with the height of the tip from the metal when there's warpage, so by that standard, the DTHC IV runs great. I just figured that because I run everything super slow though (95ipm on 16ga) with 30amp consumables, that the voltage @ 38-41 was normal. It wasn't until I attempted this super thick .75in cut with voltage readings at 52 with the DTHC turned off, that I thought hmm.. maybe something is off.

[chattacuda]

Well, your tip voltage readout on mach sounds like mine. But my torch never moved off the 0.06 cut height and there was no torch up or down commands showing on mach. Like you, the plasma machine cut fine. When you say the 'voltage changed with the material when there was warpage, I am confused as the torch should move to keep the tip voltage ( your 38-41 number) to the setpoint voltage you have for the material you are cutting ( eg 117v). After I did the 126 volt PWM test, I tested the DTHC per the instructions in the CandCNC manual which sends a 150 volt and 100 volt signal to the mach with a 125 v setpoint ( i think) and you verify it reacts with torch up and torch down commands. When that was good, I read some more on the CandCNC forum and saw where Tom had advised a customer to check the output from the PM45 by pulling the stereo jack from the PWM and reading voltage between the tip of the jack and the first ring with a digital voltmeter with the torch fired in air and it should be about 3.5 -4 volts ( I am not sure the exact number but I think this is close). Mine turned out to be 0.75 v which is exactly 1/50th of the 38 v I was reading on mach as tip volts ( same as you). Based on that, I took the front cover off the PM45 and saw there was an error LED lit ( can't see with the front cover on. So I took it to the repair center and they replaced the control board. It works just like before now with the Tip Voltage controlled by DTCH to the setpoint voltage. Let me state here that Jim Colt said above the voltage test with the torch fired in the air was not necessarily a good test. You do have a problem though as the tip voltage readout should be the same as your setpoint voltage during cuts ( or reasonably close).

[Capstone]

Thanks for the explanation. I think I get it now. My DTHC IV "works", just at the much lower settings in MACH. If the DRO reads .1 instead of .06 lets say, then I can bump the voltage down on the fly in MACH as it's cutting to lower the "Z" to reach the desired cut book spec cut height, and if the metal starts to warp, the "Z" will still adjust to maintain the matched pair of voltage settings on the MACH display. The question is, assuming the Voltage Divider is defective (I'll look under the hood tomorrow), does it really matter what the voltage says, if I'm adjusting the toolsets throughout the entire chain to "trick" the DTCH IV into cutting at the correct cut height

I'm really trying to avoid having to spend money on a repair and/or lose the use of my machine for an extended amount of time if all were talking about is a numbers game where I can use "kentucky windage" to fix the problem instead.

[jimcolt]

Here's how you check the voltage divider output of the Powermax45.

"The way to check the voltage divider output is to cut a part with the torch at a fixed height...then read the voltage divided output voltage on pins 5 and 6 at the CPC receptacle on the Powermax45. This will read 1/50th of the actual arc voltage....so pins 5 to 6 will be between 1.5 and 3 volts dc while cutting. A reading while firing a pilot arc is mostly irrelevant.....as you have not created a work path through the work clamp"

From what you have written....sounds like the voltage divider output is working to me.....if it was not working you would likely read zero voltas on your digital readout (with THC on or off) and the torch would rise until the arc extinguished with the THC on. Jim Colt

[Brand X]

Candcnc digital probe/with the card setup works extremely well.. I am setting one up again, since I don't want to buy a automation card for my backup plasma.. Only real difference is the Candcnc has more settings, to fine tune if you like.. It runs on 7-1 voltage..