Esab PCM-875 Plasma Cutter Troubleshooting

[TBWeldor]

So just tonight I picked up a used, non working 875 from craigslist. The price was just too good to pass up, the consumables it came with and the torch is worth more than what I paid if the machine is total junk! Anyways... I am not familiar with these machines at all. I'm going to start taking it apart tonight and see if there is anything obvious, and am posting to see if anybody has any ideas of what to look for.

I need to get another plug for the unit before I can test it, but the gentleman I bought it from said that he used it sparingly, it was working one day and the next it didn't... He said it "starts out sounding fine, like it's in its high frequency start mode, then it never kicks over to start cutting."

Any ideas?

[soutthpaw]

So just tonight I picked up a used, non working 875 from craigslist. The price was just too good to pass up, the consumables it came with and the torch is worth more than what I paid if the machine is total junk! Anyways... I am not familiar with these machines at all. I'm going to start taking it apart tonight and see if there is anything obvious, and am posting to see if anybody has any ideas of what to look for.

I need to get another plug for the unit before I can test it, but the gentleman I bought it from said that he used it sparingly, it was working one day and the next it didn't... He said it "starts out sounding fine, like it's in its high frequency start mode, then it never kicks over to start cutting."

Any ideas?

Well if it's in HF start mode, that pretty amazing as the 875 is a pilot arc plasma and does not have HF. This is also a transformer, not an inverter machine. Which should mean troubleshooting is easier and repair is less expensive. Never had to open mine in the 10 years I had it.

[Brand X]

875 has a high freq start, and is a inverter too. (IGBT type)

Not the correct service manual, but you get the idea.. Look through Esab manuals for the exact one you need..

http://www.esabna.com/literature/pla...f-15-424-a.pdf

[soutthpaw]

875 has a high freq start, and is a inverter too. (IGBT type)

Not the correct service manual, but you get the idea.. Look through Esab manuals for the exact one you need..

http://www.esabna.com/literature/pla...f-15-424-a.pdf

Is that the newer rounded ones? I have the old square/all metal version

[Brand X]

Sq model.. Just for your info the first blowback torch came on the ESP-50 machine.. It had a power supply based on the 875.. round or Sq, they all are the same IGBT type, with High freq start with pilot arc.. Had a 1125 sq case -70 amp machine, and a round case 1500 also..

You can see in the manual it uses the same torch as yours. The rounded models used the PT-32 torch. I believe even on the 60 amp machine.. The older model you could not retro the newer style torch, That is why so many 875, and 1125 have the SL-60/100 thermal dynamics torch on them. The lower power 60 amp machine was not terrible with consumables, if cutting at 50 amps. The 70 amp machine would eat them like candy..Electrodes would about vaporize.. I still thing the older sq machines are good to this day.. I even like the powercut 650 really well.. That's after using most new machines. The tiny torch is king . (IMO)

[soutthpaw]

Sq model.. Just for your info the first blowback torch came on the ESP-50 machine.. It had a power supply based on the 875.. round or Sq, they all are the same IGBT type, with High freq start with pilot arc.. Had a 1125 sq case -70 amp machine, and a round case 1500 also..

You can see in the manual it uses the same torch as yours. The rounded models used the PT-32 torch. I believe even on the 60 amp machine.. The older model you could not retro the newer style torch, That is why so many 875, and 1125 have the SL-60/100 thermal dynamics torch on them. The lower power 60 amp machine was not terrible with consumables, if cutting at 50 amps. The 70 amp machine would eat them like candy..Electrodes would about vaporize.. I still thing the older sq machines are good to this day.. I even like the powercut 650 really well.. That's after using most new machines. The tiny torch is king . (IMO)

According to the manual, the HF start is in a desperate HF arc starter part #37338, used for mechanized cutting (page 25. Of manual)
But I stand corrected, it used IBGT's. It sure feels heavy enough and needs 49 Amps on single phase. So when I was told it was a transformer it just made sense. It mentions it in the service section at the end of the manual which I had no need to use.
There is a troubleshooting walkthrough in the service section the OP can use.....
Manual here. https://drive.google.com/file/d/0BzZ...p=docslist_api

[TBWeldor]

Sq model.. Just for your info the first blowback torch came on the ESP-50 machine.. It had a power supply based on the 875.. round or Sq, they all are the same IGBT type, with High freq start with pilot arc.. Had a 1125 sq case -70 amp machine, and a round case 1500 also..

You can see in the manual it uses the same torch as yours. The rounded models used the PT-32 torch. I believe even on the 60 amp machine.. The older model you could not retro the newer style torch, That is why so many 875, and 1125 have the SL-60/100 thermal dynamics torch on them. The lower power 60 amp machine was not terrible with consumables, if cutting at 50 amps. The 70 amp machine would eat them like candy..Electrodes would about vaporize.. I still thing the older sq machines are good to this day.. I even like the powercut 650 really well.. That's after using most new machines. The tiny torch is king . (IMO)

According to the manual, the HF start is in a desperate HF arc starter part #37338, used for mechanized cutting (page 25. Of manual)
But I stand corrected, it used IBGT's. It sure feels heavy enough and needs 49 Amps on single phase. So when I was told it was a transformer it just made sense. It mentions it in the service section at the end of the manual which I had no need to use.
There is a troubleshooting walkthrough in the service section the OP can use.....
Manual here. https://drive.google.com/file/d/0BzZ...p=docslist_api

Thank you for the links and information. It is a 60 amp machine, I've taken the cover off and there is nothing glaring... no fried circuits that I can see. I downloaded and printed the manual, man - there sure are a ton of parts in these things! It's pretty dusty inside, so I think I'll clean it out and fire it up tomorrow to see what happens. This may be a very involved troubleshooting... but hey, for $50 I'm willing to spend a good amount of time on it.

[soutthpaw]

Thank you for the links and information. It is a 60 amp machine, I've taken the cover off and there is nothing glaring... no fried circuits that I can see. I downloaded and printed the manual, man - there sure are a ton of parts in these things! It's pretty dusty inside, so I think I'll clean it out and fire it up tomorrow to see what happens. This may be a very involved troubleshooting... but hey, for $50 I'm willing to spend a good amount of time on it.

I'd be interested in a couple parts, possibly the torch and consumables I'd you can't fix the thing and want to get your money back on it.

[TBWeldor]

I'd be interested in a couple parts, possibly the torch and consumables I'd you can't fix the thing and want to get your money back on it.

Sounds good, you'll be first in line!

[TBWeldor]

Before I button it up to test it, and because everybody loves pictures...


Well it looks like even if a circuit board is bad that there are companies that will fix them, it just might be difficult to track down exactly what is going on.

Anybody have an opinion of how much it's worth putting into? It's an older unit, but from a cursory glance, even if I need to put $500 into it it would be worth it I think.

[TBWeldor]

So I put a new plug on, hooked the air up and turned it on... and yes it does in fact turn on. It pretty much does everything the previous owner said, the air starts and the pilot arc strikes, but no main arc.

According to the manual, it could be something super easy as in something wrong with the torch head, or something major, like a control board... I need to do a couple electrical tests with it plugged in, but here are some pictures of the torch head. It looks dirty to me, what's the best way to clean inside the actual torch head?
Also, the flow switch is supposed to come apart to clean the spring inside... however so far I can't get it apart.

[tjb836]

Here is a link to the service manual, if you don't already have it.https://www.google.com/url?sa=t&rct=...qLj23fvD0E1LqA

[Jawslandshark]

My 875 is the round one (yellow torpedo) but sometimes it does the same thing and I just replace the consumables and it fires right back up. I think it's the PT-32 torch though, very picky. I am glad I don't use the hand torch on it much. I think it's a torch issue, these machines are built pretty tough and your looks in real good shape.

[soutthpaw]

So I put a new plug on, hooked the air up and turned it on... and yes it does in fact turn on. It pretty much does everything the previous owner said, the air starts and the pilot arc strikes, but no main arc.

According to the manual, it could be something super easy as in something wrong with the torch head, or something major, like a control board... I need to do a couple electrical tests with it plugged in, but here are some pictures of the torch head. It looks dirty to me, what's the best way to clean inside the actual torch head?
Also, the flow switch is supposed to come apart to clean the spring inside... however so far I can't get it apart.

That part is replaceable and there is an updated part kit that comes with it's own special installation tool. I'll take a pic of it this weekend. I got mine off eBay several years back as old stock being sold off.

[Brand X]

It'd still hi-freq machine with a pilot arc start. Because it can take a additional arc starter for the machine torch does not change that fact..

[soutthpaw]

Here is the old and new seat and tool.

[TBWeldor]

It'd still hi-freq machine with a pilot arc start. Because it can take a additional arc starter for the machine torch does not change that fact..

If I'm understanding you right you're saying that the pilot arc can start without the high frequency kicking in? I "assumed" since I saw the pilot arc that the HF was working. There is a protocol in the manual to check the HF... If that's the case then I have a direction to head. Thanks!

[TBWeldor]

Here is the old and new seat and tool.

Excellent, thanks for taking the time to take a picture. Do you have a good online source for parts/consumables? Some googling doesn't come up with much, and prices are all over the place. It seems like they think Esab parts are gold plated, and the chinese stuff is, well, chinese stuff, getting 100 pieces for the price of one esab branded sort of thing...

[TBWeldor]

double post...

[MrKirby87]

Thanks to everyone for helping to get TBWeldor up and running with the ESAB Plasma. Feel free to call our tech services line at 1 800 ESAB 123 to get one of our plasma specialists too if you hit a dead end. In case you cannot get the 875 up and running, we have a $12/amp trade in on ESAB plasmas to purchase a Thermal Dynamics one (trade in value at the lower of the 2). Just something to consider if you have to spend anything considerable to get it fixed. Either way a $50 investment was well worth it, great find!

[soutthpaw]

Excellent, thanks for taking the time to take a picture. Do you have a good online source for parts/consumables? Some googling doesn't come up with much, and prices are all over the place. It seems like they think Esab parts are gold plated, and the chinese stuff is, well, chinese stuff, getting 100 pieces for the price of one esab branded sort of thing...

I use the consumables from 3 shop river on eBay with pretty good results. Except for their 30 amp tips are not drag tips so I get original ESAB versions of those. I prefer the pointed electrodes and seem to get a better cut with them. I think Brand A prefers the stubby square end ones.

[Brand X]

I never tried the other style electrode with my 1125..(PT-27) I upgraded to the 1500 (PT-32torch) not long after owning the 1125..The China consumables really only work/last in the PT-31XT torches.. on the smaller 30/35/40 amp machines.. My friend did end up with a SL-60 torch on his 1125..(Right off the bat) The Esab is still going strong, and he has my old Thermal 151, and a Hypertherm 85 also.. Can't kill the Esab off if he tried.. He cuts more metal then a 100 average fab guys too....(Roy here knows him too) I think you should fix the 875 if you can reasonably (IMO) it's a powerful true 60 amp machine..

[soutthpaw]

I never tried the other style electrode with my 1125..(PT-27) I upgraded to the 1500 (PT-32torch) not long after owning the 1125..The China consumables really only work/last in the PT-31XT torches.. on the smaller 30/35/40 amp machines.. My friend did end up with a SL-60 torch on his 1125..(Right off the bat) The Esab is still going strong, and he has my old Thermal 151, and a Hypertherm 85 also.. Can't kill the Esab off if he tried.. He cuts more metal then a 100 average fab guys too....(Roy here knows him too) I think you should fix the 875 if you can reasonably (IMO) it's a powerful true 60 amp machine..

I just can't justify the $600 ish for the sl60 gun plus whatever the backend adapter cost, then buying a couple hundred bucks in consumables, I'm half way to a new plasma, and who ones how many China consumable I could buy for that. For hobby use it's just not worth the investment. I'd jump on a cheap used torch or a broken machine with it for $50 though

[Brand X]

You could probably change out the torch for half that easy. Not that you should, but less $$$ then you think.. The non-ATC torches come up on Ebay once, and a while.. Factory 60 amp Victor tips are not much more then the China Esab stuff.. Bit more, but like $20.00 for ten tips on Ebay.. Just got a batch today.I would not waste my time with aftermarket tips for the Thermal.

[TBWeldor]

Thanks to everyone for helping to get TBWeldor up and running with the ESAB Plasma. Feel free to call our tech services line at 1 800 ESAB 123 to get one of our plasma specialists too if you hit a dead end. In case you cannot get the 875 up and running, we have a $12/amp trade in on ESAB plasmas to purchase a Thermal Dynamics one (trade in value at the lower of the 2). Just something to consider if you have to spend anything considerable to get it fixed. Either way a $50 investment was well worth it, great find!

Well I think it's time to give ESAB a call... I checked for continuity in all the main wires and torch switch, everything checks out fine. Also adjusted the High Frequency gap because it was a little too wide. It gave the pilot arc a little more veracity, but thats about it. The manual says that if there's HF, air and pilot arc, then it's either a bad ground, (checked) bad consumables (changed), or time to bring it in basically. I'm guessing since it doesn't state what could be wrong that it's probably major.