OT took my plasma cutter in for repair

[Abner]

OMG, that went in circles.

SO, now real questions.
First, make and model of the unit.
Second, where are you in regards to Ohio?
Third and maybe important and maybe not is I DO repair them at board level depending on what it is, and what got smoked. And if it's a decent unit or a crap import that is under designed, and some of the big name stuff meets that spec as well as the import stuff. Lincoln Pro-Cut 55 was one that didn't have the cooling ability built in for being run hard. And they would burn a board that cost $917.00 to replace and you were burning up 8 parts that cost 3 buck each.
Ask me how I know.
The fan actually would run too fast to leave the air in place long enough to effectively transfer the heat from the heatsink to the air before being blown out the other end.

Anyway. Make Model and specific what's it doing. Pictures of the inside of the cabinet may help as well.
It don't work is nice, but does it power up?
Do the lights come on?
When you pull the trigger does the air flow start and it just don't apply power to the torch and cut.
Does it sound like it's trying to apply power AKA air flow starts and then it sounds like a transformer buzz but it don't cut. That sort of description.

Answers; - please forgive my terminology if it is incorrect - live green plants are my lively hood(not marijuana).
Thermal Dynamics pak master 38xl (29 amp)
Ohio - Oregon
Powers up, runs a pressure test, fan hums, lights come on.
Ground clamp attached to shiny steel, hold torch down and press button, air comes on but there is no arc, no change in noise from the unit.

Pictures - I will go pick up my unit Thursday, if you don't mind waiting I will get some for you.

Many Thanks,
Abner

[J Tiers]

.....

The thing in common with all four cases was that the companies made money doing things might have fixed the problem, but they were not at all sure if what they were doing was valid. And that's why they do it. They can make more money by fixing it twice or three times.

Dan

Yes, it happens.

And, yet, a guy I know ran a car repair shop for decades, making good money, and his "thing" was that he did not do that. They always knew why they were replacing what they replaced. His shop was well known as "the place" to take the car to get it fixed right, no hassles. Last I heard, he had retired, but the shop was still going on the same lines.

[danlb]

Yes.... Proving the part bad is the reason for replacing it. Otherwise I have no idea why one would do it.

It happens quite often when the fault is hard to diagnose or takes lengthy test procedures. It's quicker for them AND they get paid either way.

Example 1: Friends's expensive Mercedes CEL (check engine light) was on permanently. When cleared it would come back on with an hour of driving. The dealer replaced several sensors (one at a time) and an electronic module. They never did find the problem. He paid $3000 trying and eventually sold the car as is.

Example 2: Mom's car currently has a problem where the dashboard goes crazy after a short drive. Local Cadillac dealer diagnosed it as a bad alternator, then a bad battery and finally several bad sensors. It's still broken. She's out $2000 on a car that is barely worth $5000 and it's not safe to drive. That's taking advantage of an 80 year old widow.

Example 3: On a hot day, the house AC would cut out right after starting when temperatures exceeded 100 degrees all day long. Repairman said it needed charging. Did so and charged a small fortune since it was an old freon unit. He said the entire system needed to be replaced if it happens again. Next hot spell it was doing the same thing. I checked all of the electronics, and traced the problem back to the thermostat. Replaced it and it's worked fine for 6 years.

Example 4: On a below zero day in Lake Tahoe, my hybrid did not want to start the first 3 times. The error display made no sense so off to the dealer we went. The Tahoe dealer said that it should be safe for the trip back to the central coast. Got it to my dealer, who diagnosed it in minutes and declared that it needed a new "computer" because my model has a software bug that only shows up in cold weather. When I got the invoice they had replaced several parts including a "fuse relay" and a sensor. A bit of investigation shows that they replaced EVERY PART that the manual said MIGHT throw that trouble code. I'm convinced that they did not test any of the parts.

The thing in common with all four cases was that the companies made money doing things might have fixed the problem, but they were not at all sure if what they were doing was valid. And that's why they do it. They can make more money by fixing it twice or three times.

Dan

[J Tiers]

I understand that. I've made a living diagnosing things and fixing them. But part of my diagnostic technique was to prove a part bad before replacing it. Yes, there are places where you can't do that easily, but charging a customer $1000 for a repair that does not fix the problem seems wrong.

Dan

Yes.... Proving the part bad is the reason for replacing it. Otherwise I have no idea why one would do it.

And, as Dan or anyone else who fixes electronics knows, the bad part had to GET "bad" somehow. Yes, it could "just fail". But it pays to look around and find out what ELSE around it is bad as well. And look for root causes.

Once, when I was on vacation, one of the techs built my new prototype PWA. He did not do the preliminary checks, he built it and fired it up. Well, there was something wrong, I don't recall what (I think it was a part put in wrong), and some parts failed. So, genius-boy checked through it, and found a bad part, which he replaced. And turned it on again.....

Of course it failed. So now he found another bad part besides #1, and replaced both of them. And turned it on.... To make a long story short, he managed to blow through my entire stock of the new, hard-to-get semiconductors, that were supposed to build several boards, and he never did get the one working. I was NOT pleased, and suggested that the tech manager arrange some troubleshooting training. offered to help with that (he did not take me up on it) I did get the thing working, because I found a few more sample parts that had gotten set aside. All it took was to find ALL the bad parts, plus the part that was put in wrong, and replace them all at once, instead of one at a time.

Replacing bad boards on a guess is a poor way to do repairs. Especially when it is very likely to result in a "not fixed" situation, possibly with the replacement board now also bad.

[danlb]

I can't guarantee the diagnostic will identify your problem, all I can do is tell you what I found and state my hypothesis as to the cause. Sometimes that hypothesis will prove to be wrong or will actually be right and another problem will be revealed.

I'd like to offer you your money back if the diagnostic is incorrect, but I just can't have confidence in my diagnostic until it's tested and at that point the device is fixed.

I understand that. I've made a living diagnosing things and fixing them. But part of my diagnostic technique was to prove a part bad before replacing it. Yes, there are places where you can't do that easily, but charging a customer $1000 for a repair that does not fix the problem seems wrong.

Dan

[J Tiers]

.....

I'd like to offer you your money back if the diagnostic is incorrect, but I just can't have confidence in my diagnostic until it's tested and at that point the device is fixed.

Very true...

The proof of the diagnosis is that fixing the diagnosed problem fixed the unit. So simple, so obvious, and so true.

Goes right along with "fix what you know is wrong".

[Puckdropper]

I don't mind paying a diagnostic fee IF the diagnostic comes with a guarantee that it has isolated the problem. I've never found a repairman who would diagnose it, then refund all money paid if the fix does not work.

Dan

Imagine a series of walls between you and the device working. Some walls are small (switch has to be in the on position) and others are large (missing gear) or even hidden (clear gunk over locomotive wheels). All a diagnostic can do is identify some of these walls, but some walls hide other walls so you've got to actually find and fix those problems first.

I can't guarantee the diagnostic will identify your problem, all I can do is tell you what I found and state my hypothesis as to the cause. Sometimes that hypothesis will prove to be wrong or will actually be right and another problem will be revealed.

I'd like to offer you your money back if the diagnostic is incorrect, but I just can't have confidence in my diagnostic until it's tested and at that point the device is fixed.

[OhioDesperado]

OMG, that went in circles.

SO, now real questions.
First, make and model of the unit.
Second, where are you in regards to Ohio?
Third and maybe important and maybe not is I DO repair them at board level depending on what it is, and what got smoked. And if it's a decent unit or a crap import that is under designed, and some of the big name stuff meets that spec as well as the import stuff. Lincoln Pro-Cut 55 was one that didn't have the cooling ability built in for being run hard. And they would burn a board that cost $917.00 to replace and you were burning up 8 parts that cost 3 buck each.
Ask me how I know.
The fan actually would run too fast to leave the air in place long enough to effectively transfer the heat from the heatsink to the air before being blown out the other end.

Anyway. Make Model and specific what's it doing. Pictures of the inside of the cabinet may help as well.
It don't work is nice, but does it power up?
Do the lights come on?
When you pull the trigger does the air flow start and it just don't apply power to the torch and cut.
Does it sound like it's trying to apply power AKA air flow starts and then it sounds like a transformer buzz but it don't cut. That sort of description.

[gaston]

I have 2 plasma cutters a cut50 and a 1980's century 20 the cut 50 will cut 1/2 easy but makes "angry noises and scares the hell out fo anyone in my shop... the century 20 will only cut 3/16 but hums like a kitten purring. Its old ,transformer ,weights a ton , and for 37 years worked like a slave
Take this invert stuff and shove it, I'll take an old transformer machine any day

[Sparky_NY]

I have a harbor freight plasma, bought used, which I have been very happy with UNTIL.....

A friend bought a "CUT 50" plasma from ebay for under $200 delivered. He brought it over and we set it up and tried it. It outperformed the HF unit by a LOT. The HF unit struggles with anything over 3/8 thick, the Cut 50 cut 5/8 plate like nothing ! I am half tempted to get one and sell my harbor freight plasma. At under $200 there isn't a lot of risk. My friend has been using it a lot and it works great.

Just a FYI on cheap plasma cutters.

[J Tiers]

Most factory repair places will replace the PWB, as opposed to doing "component level repair".

This is very reasonable, for several reasons:

1) You get an exact replacement, which has all the functions tested and is as good as what was put in the machine originally

2) Power electronics often fail in a more destructive manner, parts may be vaporized, traces blown off the PWB, holes burned in the PWB itself. It is not uncommon to be unable to repair the PWB in such a way that it can be re-used.

3) It is common for a power device failure to damage other parts. Usually you can determine that, but sometimes the damage is not enough to cause a failure, YET. So repairs are a crapshoot unless you replace more than appears needed.

4) The liability issue is easier if ONLY factory parts are used. You can get in trouble replacing components unless you use the exact original component, and know if they are specially selected, etc. You can hardly go wrong using a factory original assembly, since you make no decisions, redesign nothing, and are not putting in any substitute parts which can later be described as "cheap, inferior, substitutes". There is no "knew, or should have known" involved.

[dbq49er]

Possibly, to both. Or, you may be lucky.

If the unit is basically well designed, then it may last 20 years. Perhaps more. Semiconductors last a long time if they are used within their limits. Eventually the failure rate goes up, due to physical changes in the parts over time. Usually power semiconductors fail, because the high voltages cause gradual changes in the actual structure of the parts.

if, on the other hand, there is an inherent weakness in the device, then the spares for parts which fail may rapidly be depleted, leading to unrepairability. This tends to occur more with units made in china, because the sellers (who did not MAKE the thing) have to guess how many spares to order with the production order. They cannot get just a few made if they need more to service a problem, the chinese will not accept that sort of order, you must order a "production" type run of many thousands. Gettig a few made here is not an option, because only the chinese have the production data.

In some cases, such as HF, the company may not order ANY spares, and when anything fails, your options are to replace the unit, fix the bad part, or somehow make your own replacement part. Someone commented recently that HF did not even sell actual consumables for certain products, common things you were CERTAIN to need.

Back when things were made here in the US, the manufacturer would have parts as long as they were making the units, and would have spares, know what they needed, were able to produce new parts to fix any problems, etc. That does not occur with stuff made in china, even if it is designed here.

Of course US makers were not perfect. One well known brand of clothes washers made a high priced new model, which had some fault with a particular electronic assembly that made them fail in some units. They decided not to fix the problem, but to simply replace the boards if they failed. But, after replacing the assembly a couple times, they would announce to the customer that they would not replace it again for free, despite the warranty. Nice.....

And, the product manufacturers are at the mercy of the semiconductor suppliers. Electronic parts are only made for a certain time, and then are replaced by new and better parts, which rarely can be directly used in place of the old. So when that happens, the product manufacturer must either spend money to redesign an old product, or obsolete it and replace with a more modern product using newer parts. They will always do the new product, of course.

And, since no more PC boards for the old units are being made, they get in short supply, at high prices.

I purchased a HF plasma cutter and then started to get educated about the pros and cons of the machine. HF does sell consumables but you can go to http://www.georgesplasmacuttershop.com/ and get all you need to your door. As others have said, what if it quits? Well http://www.georgesplasmacuttershop.com/ can fix it for you. I know because I needed his service. He was a tech for HF and knows about all kinds of machines. Look at his web site and if you need you can call him for great info and help. I hope this helps!!

[Black Forest]

Yes they should have done that if you called them, or at least when you brought it in. But that does not alwys happen. Sometimes the person who takes in the things at the counter does not know much (why they work the counter instead of fixing things).

But the person who worked on it presumably should have known that, if it was a common issue and common brand, and if so should have called you to say so before doing anything. Back then we would do that, and make sure everyone knew it was a risk.

But if it was not known, then you can hardly blame the repair folks... If they call for parts and to their surprise are told there are none, they are in the same boat with you. Half cost for diagnosis would be fair (at least to people who do not instantly explode ).

The store/repair center was a Karcher store. The unit was a Karcher unit and before I went off on them I asked them if they knew there were no parts available before they started on the machine. They answered in the affirmative. And for your information I don't instantly explode. It takes at least five seconds!

[J Tiers]

They knew before I even brought the machine in that there were no parts available for the unit. They should have told me that over the phone as well as stating that they could look at it and maybe it would be something like a bad connection or are broken wire and possibly they could fix it but if it needed any parts then it was a no go. Then the risk would fall on me to decide. They are the professionals not me. It was their attitude as well that pissed me off. I am a very generous person and have helped many people but if you try to screw me I will go to all lengths to extract justice.

Yes they should have done that if you called them, or at least when you brought it in. But that does not alwys happen. Sometimes the person who takes in the things at the counter does not know much (why they work the counter instead of fixing things).

But the person who worked on it presumably should have known that, if it was a common issue and common brand, and if so should have called you to say so before doing anything. Back then we would do that, and make sure everyone knew it was a risk.

But if it was not known, then you can hardly blame the repair folks... If they call for parts and to their surprise are told there are none, they are in the same boat with you. Half cost for diagnosis would be fair (at least to people who do not instantly explode ).

[Black Forest]

A long time ago I worked in hifi repair shop while in school. We had guys act like that from time to time.... Folks who did not want to pay for our time to take the unit apart, find out what was wrong, and determine that the part was not available. Folks who thought that they were entitled to serf labor for free, most of them.... they bought the unit, and they apparently thought that they bought our time when they bought the unit.

We told them that our billing rate was posted right up on the wall in front of their face, that our minimum diagnostic fee was up there also, so they knew that when they brought the unit in. They could pay the bill and get the unit back along with the information of what was wrong, or not pay and leave the unit. If left 60 days, we could dispose of the unit.

Told them they were welcome to call the police, the manufacturer, whatever they wanted to do. A couple did call the police, and were told by the responding officer not to waste his time. They usually threatened to call everyone and have our business license pulled, or whatever, but nobody ever did.

Nobody got their unit back with no payment, unless we had decided to handle it that way before the guy ever came in (there were a few).

That's life in retail......

They knew before I even brought the machine in that there were no parts available for the unit. They should have told me that over the phone as well as stating that they could look at it and maybe it would be something like a bad connection or are broken wire and possibly they could fix it but if it needed any parts then it was a no go. Then the risk would fall on me to decide. They are the professionals not me. It was their attitude as well that pissed me off. I am a very generous person and have helped many people but if you try to screw me I will go to all lengths to extract justice.