Max100 problem

[gridley51]

Have a Max100 on a Messer Silver Bullet cnc table.Has been cutting great,but started faulting out when the torch dropped to start the arc.Did a bit investigating and found no high frequency arc.Set the spark gaps and now ok.
What happens now is torch drops and high frequency arc appears to be there although a bit greenish in colour.Main arc does not start.I have the recommended 280 vdc at the torch leads at the machine end and the fuse is ok.
Any ideas?

Mark.

[Alan Bradford]

I would look at the Pilot Arc Relay.
I dont remember the CR number but it is in the left side.
I would bet the contacts are welded shut.
The Green you see in the arc is burning copper.
Not good for cut quality or consumable life.
If the PA Relay is OK then check for an air flow problem or cracked torch.

Good Luck

[gridley51]

Thanks for the reply Alan.I have the pilot arc,didn`t know this was seperate from the high frequency arc so,the pilot arc relay is ok.Well it`s ok and working but only just as it`s showing a lot of wear so I will replace it.
Problem appears to be current sensor not sensing pilot arc current so control board is not getting signal to output the analogue voltage to the chopper unit.This was proved by putting a magnet in close proximity to the sensor after the pilot arc was established.Main arc transferred and cut normally.
Current sensor is slightly special in that it sinks the output when it senses current.It`s a Honeywell part,stocked in the USA but can`t find one in UK so have ordered one from Hypertherm in Holland.Will be interesting to see how prices compare.
As a side note,having spent the best part of a day off and on down on my knees checking through this setup I think I may stick the MAX100 up on a stand to make future maintenance easier.
Another side note,spoke to Hypertherm`s technical support people in Holland to get a second opinion on my findings.Takes a few tries to get through to either customer support or technical support as the lines seem to be very busy but,well worth it it in the end.Had a very enjoyable,enlightening and funny conversation with a tech who has never seen a Max100 but who could answer all my questions and offer suggestions while studying the schematics.
Only downside was although it`s a free 0800 telephone number to tech support my telephone contract allows only calls starting 01,02 and 03 to be free so it cost me.
Mark.

[Alan Bradford]

I think you will find it to be a possible cracked torch or another return path through the Pilot Arc lead in the torch lead package.
The reason I suspect it is you say you see a Green arc.
Green is burning copper.
This would not happen if it was just a defective current sensor.
Some of the pilot arc current may be returning through the nozzle face to the PA circuit and not the work lead. This would keep the current sensor from seeing enough current to trigger the sensor.
The magnet near the sensor will trip it anyway. (BTW I came up with that Max-100 trick with the magnet when I worked at Hypertherm Tech Support in 1989). It also works on the Max-200, HT-2000, and HT4000

Turn off the main power to the Max-100.
Check for any continuity from the nozzle to the positive work lead.
You may see 20k-300k ohms. That is normal.
If you see anything below 5k or so look for a short in the torch head or leads.

Good Luck

[gridley51]

Thanks again for the reply Alan.
I have fitted the new current sensor and the main arc is now transfering and the system is running.
Unfortunately the cut quality is crap.It now turns out that was the original problem before it stopped altogether.It will only cut at about two thirds of the speed it was running at and on 3/16" steel the part is not severed cleanly.It would look as though there was not enough air or current.The flow seems ok but hesitates for maybe a second at half pressure before reaching the setting.This used to be instant.Have checked the solenoid valves individually and not happy with Sol3 which is the step valve.Will strip that one for a look.
Have capped the torch and put the air on to check for leaks and all ok.
Pilot arc drops out instantly when main arc comes on so I think that is ok.
Have checked all the resistances between the torch,source,machine and ground and happy with them.
Still have the current to check whilst cutting.
Any other suggestions welcomed.
Mark.

[Jonp]

We have a max 100 on our cutting machine and it started cutting very bad and using lots of consumables, after much monkey business we found our problem with the contactor, on the side with the main transformer there are two contactors that appear identicle, the botom one is the input power contactor it was like new , the upper one is the plasma power contactor and the points were very badly burnt, we replaced them and the machine cuts like new, Good Luck, Jon P.

[matttargett4]

Jon P

How did you get on with this one? I ave the same troubles, my arc doesnt seem to transfer properly but if i use the expanded metal setting it works fine but cut speed is slow and quality is hopeless, i changed the current sensor but it made no difference, any ideas or pointers??

Matt

[matttargett4]

I meant Mark not Jon P but comments from anyone are welcomed!!

I took a couple of resistance readings today, between the torch electrode and the earth lead of the plasma, i think thats what someone refered to as the positive but the other one anyway way, i get 5M ohms, between the shield and the other lead i get 125k, does that sound normal??

Thanks

Matt

[Alan Bradford]

You nered to check from the electrode (Negitive Lead) to the Pilot Arc Lead.
It shooud read Open.
If it does not (less than 1 meg) then
I think you may have a stuck Pilot Arc Relay (1CR)
If that is stuck or welded shut you will get very short nozzle life (1-10 pierces) and poor cut quality/reduced cut capacity/slower speeds.

Air leaks in the system or torch will also have similar symptoms.

Good Luck

[matttargett4]

Alan,

So i need to test from the electrode to the pilot arc lead, where is the pilot arc lead?? Is it in the cutter or in the torch?? Im assuming it is the other lead in the torch?

Funny you should mention air leaks, the torch does hiss when the power is on but not cutting, the hiss is not as loud as when i switch over the test switch, i had figured this didnt matter too much and was just some grit in a solenoid, im interested to know more, do you think that could be the problem??

Thanks

Matt

[Alan Bradford]

Both hoses have electrical leads in them .
The Pilot Arc Lead is the shorter, smaller lead on the torch and the Electrode (Negitive) is the larger Lead.
Measure between these two leads and you should read an open circuit.
Use an Ohm Meter and not a continunity tester, as will give you a false good reading.
If you have a high reading, you may have a cracked torch.
Disconnect the torch and measure the hoses.
If you still get a reading then the Pilot arc relay 1CR may be welded closed.
The manual shows the location.
If you do not have a manual you can download one at Hypertherm.com.

As for the air leak, the small hose (Pilot Arc) also carries the air for the 'Cap Off Sensor'.
If it leaks too bad it will prevent the machine from turning on.
Check the 2 O-Rings on the torch, and the Retaining cap. Replace if worn, leaking or bad.

Good Luck

[matttargett4]

Alan,

Ive tried all of those things, i have an apoen circuit on both of those tests and i have narrowed the problem a bit more, if i leave the cutter unused for a couple of days when i restart it the arc will not transfer from the pilot arc to the main arc, if i switch on to the expanded metal setting the arc starts ok, if i then switch back to normal operation mode after the first pierce it will pierce with no problem so long as i have the air in the test position so it runs all of the time, the cut quality is pretty good and i can achieve the recomended feed rates, im not too sure about consumable life. I still have the air leak on the torch, i think that is perhaps to do with the o rings so i have ordered some more although the air seems to come out of the nozzle not the retaining cap, so im hoping the o rings will mean i dont have to use the test setting but i have no idea why the arc wont transfer after sitting for a while? Any ideas? Im tempted to look for the contactor mentioned earlier in the thread and the pilot arc relay and replace them if they arent too expensive as i wonder if its and intermittant fault with one?

Piercing at twice the cut height should be ok shouldnt it??

How long would you expect consumables to last under normal operation??

Matt