HP PM65 losing arc.

[John Bewick]

I started building my CNC table a couple of years ago, but due to the covid lockdowns, and personal problems was not finished until now.
I brought a new Powermax 65 with machine torch 18 months ago, and it has sat in its box unused until now.
The problem I am having is when running a cut program, the torch will fire and immediately lose arc.
Table is running UCCNC, floating Z axis, Price AVHC turned off at the moment, and THC turned off in UCCNC, Pre air filters and dessicant dryer, all new air lines from compressor to PM65, air pressure guage at PM air inlet shows 120 psi, dropping to 110 when cut cycle running.
I have tried changing the torch consumables with spares that came with the machine, and I am sure there is nothing sticking, but no different. 'O' ring looks good.
Torch firing height checked and measured at 3.8mm and drops to 1.5mm on cut run.
Machine clamp to workpiece all good.
Torch firing LED on screen stays on during the cut, and goes off at the end of cut, and I can hear the torch firing relay operating when it does.
No fault code, or fault LED displayed.
Can anyone suggest what may be wrong. Could it be a fault with the PM65 ? I have run out of ideas.

[weldguy]

The fact that you are not seeing an error code on the PM65 LED screen leads me to believe you are losing the start signal from your controller. I realize you are seeing the "torch firing LED" on the screen staying on BUT is the relay actually still closed? I would start by confirming that with an ohmmeter on the start signal wires going to your PM65.

[John Bewick]

On checking across the start signal wires going into PM65 they measure a voltage of around 18 volts before relay closes, and drop to zero while supposed to be cutting, then back up to 18 v at end of cut, so relay is staying closed but torch losing arc.

[weldguy]

Ok, and are you 100% confident that no error pops up on the LCD screen when the arc is lost?

[John Bewick]

No error on LCD screen.

[weldguy]

Very strange. All I can suggest at this point is to enter the diagnostic screen and see if any errors are stored. This link Diagnostic Window will show you how to enter the diagnostic window and describe the stored error codes. Curious to see if anything is in there.

[John Bewick]

Sorry, I should have said I checked that after checking torch switch wiring , no error codes stored. As Jim Colt has stated in the past, if no error codes are present then it must be some external fault that the PM cannot sence, but what could it be ? I have checked most things I can think of at least twice now.

[adbuch]

Air pressure?

[weldguy]

If it was air pressure I would expect to see a fault code. Ya I am stumped also. Definitely seems external issue and not the plasma cutter. Where is your ground clamp located? Is your ground cable screwed tightly into the plasma cutter?

[adbuch]

This may have already been answered, but can you use it for hand cutting without the table, i.e. manual cutting and it performs as it should?
David

[adbuch]

Also, make sure you have not bumped your knob from the cut setting to the gouge setting on the front panel of the plasma cutter.
David

[John Bewick]

Ground clamp screwed tightly into PM, and clamped to work sheet of steel, which is not rusty. Air pressure at PM inlet never drops below 100 psi. Knob is on second position from top.

[adbuch]

Can you cut manually using hand torch?
David

[John Bewick]

Unfortunately I don't have a hand torch for the PM. While trying again this morning I did get a fault code and fault light come on. Showed 0-30 code. Removed electrode etc to check, no obvious problem so fitted another set of unused consumables, run a test, same as before, losing arc directly after firing. Tried a set of Finecut torch parts, and set up cut in Sheetcam to suit, just the same problem again.

[adbuch]

See if you can borrow a Duramax hand torch to test. If it won't cut manually, then it certainly won't work for cnc.
"Divide and conquer"

David

[John Bewick]

Thanks to you both for all the help. I know two people who have PMs, they are both on cnc tables so not sure if they will have hand torches, but will ask .

[SegoMan DeSigns]

It's sure handy to have both (I do) do the cutting with the machine and the harvesting with the hand..

[John Bewick]

In this instance it sure would be handy, but I have had a 40A manual plasma for quite a long time, and saw no reason to buy another hand torch for the PM, especially as over here in the UK they cost far more than a fairly good complete plasma package, eg over 600 UKP. My PM65 with machine torch cost me over 3000 UKP. One UKP is equal to 1.21 USD. I am a retired hobbyist so not going to make money from this. I do it to keep the grey cells working.

[adbuch]

Understood. The idea here is to attempt to find out if the problem is with your plasma cutter or your controller setup. If you are able to cut by hand, then we can most likely rule out any problems with your cutter and focus on the remainder of your system or the interface between your plasma cutter and controller. If on the other hand you do indeed have problems doing some hand cutting, then we can focus our attention on your plasma cutter.
David

[John Bewick]

Thought I should give an update on the problem. I tried to borrow a hand torch from two people I know with Hypertherm Plasmas, but they only have machine torches. I phoned Hypertherm to ask for help. Sent them a photo of service screen ( showing no stored fault codes ) and explained the problem I have. Very helpful guy told me he thought it may be a sticking solenoid in the machine, ( which sounds very likely, as it has stood unused in its box since October 2020 ) but as it is still under warranty I should contact the supplying dealer. Well, that was a shock to me, still under warranty ? I am so used to things these days only having a years warranty, and even then dealers will try anything to not honour a claim.
Anyway I phoned the supplying dealer, who is 300 miles from me, and they are having the machine collected on Monday to check it out. Will keep you posted when I have more news, hopefully good news.

John.

[adbuch]

Thought I should give an update on the problem. I tried to borrow a hand torch from two people I know with Hypertherm Plasmas, but they only have machine torches. I phoned Hypertherm to ask for help. Sent them a photo of service screen ( showing no stored fault codes ) and explained the problem I have. Very helpful guy told me he thought it may be a sticking solenoid in the machine, ( which sounds very likely, as it has stood unused in its box since October 2020 ) but as it is still under warranty I should contact the supplying dealer. Well, that was a shock to me, still under warranty ? I am so used to things these days only having a years warranty, and even then dealers will try anything to not honour a claim.
Anyway I phoned the supplying dealer, who is 300 miles from me, and they are having the machine collected on Monday to check it out. Will keep you posted when I have more news, hopefully good news.

John.

John - thanks for the update! Hopefully it is something simple.
David

[John Bewick]

Well... Machine came back with no fault found. Fitted back onto table, and yes, just the same as before.
Anyway, it is now confirmed, it is not the PM65 at fault.
Thought I would try fitting a remote switch to fire the machine manually. Removed the interface cable to connect a remote switch cable onto, and thought to first just check the wiring of the interface cable plug. WELL, it turns out the person who made the interface cable ( supplied by Extreme Plasma with the Price AVHC ) had incorrectly marked the wiring. Wires marked for torch switch were connected to terminals 3 and 5. instead of terminals 3 and 4. Terminal 5 is the Neg signal wire for voltage divider.
Rewired to correct terminals, and YES it is now working as it should.
I am not going to say what I think of the person who made that interface cable, but suffice to say, it would not be pleasant.
I just hope it has not done any harm to the voltage divider.
Thank you all for your kind help and suggestions. Now I can get on with dialling in all the tool parameters etc etc.

John

[SegoMan DeSigns]

Well the good news is your back in business and got some real time learning experience for future problem solving. In your phone call to Hypertherm did they not tell you to jump pins 3 & 4 for diagnostics?

[weldguy]

Oh man, what a drag. If the trigger wires were incorrect I would expect no arc at all but since you saw an initial arc I just moved on from there into error codes. Anyway glad you have it sorted out

[John Bewick]

SegoMan, no, Hypertherm made no suggestion of any thing to try. They just asked for me to send picture of service sreen, and from that, asked me to contact supplying dealer to organise a warranty repair. I suspect this is the first time that a fault caused by incorrect wiring of the torch switch and voltage divider wires has been encountered, so nobody was aware of the outcome. I thought it would be of interest to post this resolution to the problem, as it shows that, if the torch firing switch wires and voltage divider wires are interchanged as mine were, it will still allow the torch to fire, but not maintain an arc, I wonder why that woud be ?