|
|
Hi guys,Just picked up a PCM-750i from a friend, made in 1997, in good condition, other than the fact that it is stuck in the "ON" mode. I haven't powered it up yet but my friend has been using it like this for a while. When you turn on the main breaker switch on the back of the machine, it fires up and is ready to go without pushing the torch button, air turns on and as soon as it gets close to the work starts cutting. I'm an electronics tech and have done the preliminary checks, the torch switch is working fine and no shorts, measured right up to the main circuit board that sits on top. There are no obvious black or exploded parts. The relay, K1 is not shorted. I have the owners manual with the basic wiring diagrams, but the schematic for the main board sure would be helpful to troubleshoot this.Has anyone with the PCM series machine ever had this symptom before? Anybody have a service manual or board level schematics?Cheers!
Reply:Well I decided to put it back together and see for myself what it is doing. Turn on the power with the back switch and immediately the air turns on and the torch fires up, guessing the blue spark at the torch is normal pilot arc? This is my first plasma cutter so not familiar with correct operation. The variable current control works and it does cut steel, but never shuts off. I disconnected the torch switch wires (2 prong plug) just for laughs and it works the same, stays on all the time. Any thoughts? My guess is something on the main board.Thanks!
Reply:
Originally Posted by Kilohertz
Well I decided to put it back together and see for myself what it is doing. Turn on the power with the back switch and immediately the air turns on and the torch fires up, guessing the blue spark at the torch is normal pilot arc? This is my first plasma cutter so not familiar with correct operation. The variable current control works and it does cut steel, but never shuts off. I disconnected the torch switch wires (2 prong plug) just for laughs and it works the same, stays on all the time. Any thoughts? My guess is something on the main board.Thanks!
Reply:
Originally Posted by Slob
Have you looked at the switch that enables the torch to stay "hot" always once the button on the torch head is depressed?
Reply:
Originally Posted by Kilohertz
Yes, thanks, it's good. I think the torch button needs to be pressed to activate that though, if I understand the sequence given in the manual? Cheers
Reply:Agreed, I now think it is something on the main board that is fried, latched or otherwise not working. I checked the only relay on the board, a little reed relay, it is fine. I could fix it if I had the schematics, but just shotgunning would take forever.Cheers
Reply:I know a couple of folks personally whom have had repairs done to their Esab machines here:https://www.innovatcorp.com/2018_pc_...air_price_listEsab also offers repair service but I have no history:https://www.esabna.com/us/en/mechani...department.cfmI purchased my PCM-500i in 1996 and it's been trouble free but only used for cutting 1/4's and floorpans out of automobiles. Never taxed on the higher end.SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:Thanks again.I found that Innovatcorp site as well in my schematic search, but they want $500 to repair, and I can buy a whole machine for that locally.I'll keep searching but hopes of finding schematics are dwindling.Cheers
Reply:I just sold my 875 locally for $600 working with bunch of consumables. Did you call read and ask about service manual. As it's out of production, don't see why they would not share it with you, or at least guide you in trouble shooting.Tiger Sales: AHP Distributor www.tigersalesco.comAHP200x; AHP 160ST; MM350P, Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma. For Sale: Cobra Mig 250 w/ Push-pull gun. Lincoln Wirematic 250
Reply:Not sure if ESAB is still shopping their trade in, trade up deal. But that was $12 per amp credit on a new thermal dynamics/ESAB machineLast edited by soutthpaw; 11-29-2018 at 11:49 AM.Tiger Sales: AHP Distributor www.tigersalesco.comAHP200x; AHP 160ST; MM350P, Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma. For Sale: Cobra Mig 250 w/ Push-pull gun. Lincoln Wirematic 250
Reply:
Originally Posted by soutthpaw
I just sold my 875 locally for $600 working with bunch of consumables. Did you call read and ask about service manual. As it's out of production, don't see why they would not share it with you, or at least guide you in trouble shooting.
Reply:Esab tech support used to be outstanding in help. I don't know about lately however. Last I knew anyone having Innovat doing a repair it never exceeded $350.00 and that was extensive due to electrical surges from an unstable generator feed.SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:
Originally Posted by Kilohertz
I don't know who that is, could share contact info pls and thx? That would be awesome if they could help.Thanks!
Reply:Well thanks southpaw, you were right. I called ESAB and got thru to tech support and the fellow spent half an hour with me walking me thru the design, then emailed me the schematics for the main board. I spent about an hour going thru it but had to go to work. I'll be able to work on it again this weekend. Parts of it work fine, but the gas solenoid is stuck on all the time once it's powered up.Cheers
Reply:could be the solenoid is just sticking open.Lincoln, ESAB, Thermal Dynamics, Victor, Miller, Dewalt, Makita, Kalamzoo. Hand tools, power tools, welding and cutting tools.
Reply:
Originally Posted by Kilohertz
Well thanks southpaw, you were right. I called ESAB and got thru to tech support and the fellow spent half an hour with me walking me thru the design, then emailed me the schematics for the main board. I spent about an hour going thru it but had to go to work. I'll be able to work on it again this weekend. Parts of it work fine, but the gas solenoid is stuck on all the time once it's powered up.Cheers
Reply:Thanks Rondo, that's great.I'm working on it again this morning, working my way thru the schematics and making some progress, not fixed yet but I am learning about the circuit.
CheersPS the solenoid isn't stuck as it doesn't open until the power is applied and the circuit that drives it powers up, but thx.
Reply:Nvm...Lincoln, ESAB, Thermal Dynamics, Victor, Miller, Dewalt, Makita, Kalamzoo. Hand tools, power tools, welding and cutting tools.
Reply:Thought I would update the story...it's fixed and working great! After some extensive troubleshooting and circuit testing, I found 4 IC chips that had failed on the main board, replaced those and reconnected everything and it works as it should. yeah! No idea what caused the problem as it was like this when I got it.Cheers
Reply:
Originally Posted by Kilohertz
Thought I would update the story...it's fixed and working great! After some extensive troubleshooting and circuit testing, I found 4 IC chips that had failed on the main board, replaced those and reconnected everything and it works as it should. yeah! No idea what caused the problem as it was like this when I got it.Cheers
Reply:
Originally Posted by Slob
what were the chip numbers?
Reply:Was wondering if there was an inverter in there. The early ones were problematic. I would suspect that was the root cause but you've addressed it. Did you replace with like quality or upgrade to milspec?SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:I didn't see an inverter, as in stand alone switching inverter, although there could have been. I was focused on the main board and the logic issues. I actually used commercial parts, not MIL spec, as it will be in my heated shop. I also didn't see any MIL parts listed on Digikey's site, I was lucky to find thru hole.
cheers |
|
发表于 2021-9-1 23:19:33