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Old 02-03-2014, 12:39 PM
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Default Longevity Plasma Cutter Repair

The other day I had occasion to cut a piece of 3/16" plate with my Longevity Plasma cutter. When I turned it on I immediately noticed that the power was set to 22A or about 1/2 power. Turning the knob made no difference to the reading.
A test cut comfirmed that it was at half strength. No good for metal this thick.

I pulled off the cover and immediately noticed that the potentiometer for power setting was plugged into the top (control) board with a three conductor plug.
As I hadn't used the unit in a while, I thought that maybe some corrosion had occurred between the plug and the board. I pulled the plug out of the board (you have to squeeze the top of the plug to release the lock) and plugged it in and out a few times.

When I powered the unit up, everything was back to normal. I could set it between 0 and 40 Amps. It gave me a nice smooth cut on the 3/16 mild steel with a minimum of slag. a little touchup with a grinder and I was good to go.

I know that the company that makes the Longevity sells it under several labels so there are probably more than a few of these units out there on SFT.

You might keep this in mind if your unit starts to misbehave when you try to set the power.

Hope this helps.




DrBob
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Old 02-03-2014, 02:04 PM
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Quote:
Originally Posted by DrBob View Post

When I powered the unit up, everything was back to normal.



DrBob
Oh. Well, good.
I was afraid this was going to be another Chinese tragedy.
I'm glad it worked out.
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Old 02-03-2014, 03:14 PM
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allessence allessence is offline
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I'm glad it worked out as well..


Nice when something as simple as a loose/dirty plug is fixed and even better yet you seemed to have figured it out really quickly..

NICE!!!!!
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Old 02-03-2014, 08:22 PM
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I'm glad somebody has that kind of luck. I usually have the kind of luck where it doesn't work quite right, I pull the cover to find the beginning of the end! Black smoke covered boards usually.
In retrospect, with my plasma cutter only, I have had two issues, one a fatigued ground wire, and one a fatigued torch control connection that had gone bad. Both of these were cut and splice repairs, all my others repairs were nothing to scoff at. Mine is a Hypertherm, and I would never buy another brand machine after owning this one.
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Old 02-09-2014, 07:11 AM
Kelly Aitken Kelly Aitken is offline
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Glad yours was a simple fix. I have a Lincoln pro cut 25. It turns on and everything lights up but it won't shoot any plasma out of the torch.( I know it really doesn't shoot plasma ) I haven't had a chance to open it up and check it out. I want to up grade to a Miller 625.

Kelly
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Old 02-09-2014, 11:26 AM
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Old 02-09-2014, 01:43 PM
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Default Accurate Diagnosis - or - Luck Guess!

Quote:
Originally Posted by allessence View Post
you seemed to have figured it out really quickly..

NICE!!!!!
Before my doctoring years, I was an electrical engineering student and spent my summers working for electronic manufacturing companies on Long Island, NY.
I guess I still remembered some of it. It also helps a lot to get lucky

DrBob
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Old 02-09-2014, 02:01 PM
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Quote:
Originally Posted by cutter View Post
Oh. Well, good.
I was afraid this was going to be another Chinese tragedy.
I'm glad it worked out.
Thanks!

DrBob
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Old 02-09-2014, 02:22 PM
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Default Lincoln Pro Cut Blues

Quote:
Originally Posted by Kelly Aitken View Post
Glad yours was a simple fix. I have a Lincoln pro cut 25. It turns on and everything lights up but it won't shoot any plasma out of the torch.( I know it really doesn't shoot plasma ) I haven't had a chance to open it up and check it out. I want to up grade to a Miller 625.

Kelly
I'm assuming you checked the simple things like electrical continuity in the grounding wire and in the plasma torch lead itself.

Kelly have you checked the air pressure circuit? There's a low pressure cutoff switch that looks for a minimum air pressure before the plasma unit will start.
You might want to look to see you have enough pressure. I looked up your unit and it needs 65 lbs. If that's good, then next find the low pressure cutoff switch and jumper it out (short across the switch terminals) and see if the arc will start. If It does, replace the switch.

If that doesn't fix it Maybe Jack, Walker or one of the other plasma experts around here will have a suggestion.

Good luck,

DrBob

Last edited by DrBob; 02-09-2014 at 02:30 PM.
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  #10  
Old 02-09-2014, 02:25 PM
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Quote:
Originally Posted by Walker View Post
. Mine is a Hypertherm, and I would never buy another brand machine after owning this one.
Walker, I can't argue with you there. Hypertherm is an excellent machine. If I could justify the cost I'd probably own one too.

DrBob
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