Plasmacam control box repair

[Greavsie66]

Is there anyone who can fix the dhc control box? We had the short circuit message and have traced it back to the control box as all motors and wiring loom check out ok. Plasmacam want in the region of $2500 or £2000 to fix it as I have to pay to upgrade to design edge. I work in a school and teach engineering and this is just not possible as my whole engineering budget will be spent on the fix and I will not have any spare cash for materials or any other bits we need for the year.
If anyone has any ideas please let me know as we already started planning projects involving the plasmacam for when we go back in September.

[Rodw]

Linuxcnc maybe? I know of a school in Germany that runs abut 5 small plasma tables on linuxcnc and there is now a fully packaged configuration called Plasmac. See: http://linuxcnc.org/docs/devel/html/pla ... guide.html

Plasmac is hardware agnostic but gets best results if LinuxCNC knows the torch voltage. Mesa has a $69 card that works well for this. (Mesa THCAD)

[rdj357]

No one that I'm aware of has successfully had the controller repaired except through Plasmacam.

[Casaba]

I found a thread once where somebody overseas repaired their controller by desoldering and replacing the transistors on the board. It’s the only thread about this that I’ve ever seen and I have no personal knowledge of whether or not it’s truly possible.

https://www.cnczone.com/forums/plasmaca ... c61a993485

[ojquintero]

Bogdan Rotaru
Masa cnc de debitare cu plasma Robocut
Robomet Indurtrial www.robomet.ro

He copy PlasmaCam. but yes he repared his Plamacam Box

[WyoGreen]

It's a long shot, but you might check all the solder joints on the circuit boards. I have repaired several circuit boards lately by re-soldering suspicious looking solder connections. One board from a wireless phone had one connection that had never been soldered.

Steve

[tcaudle]

It would appear RodW (who has the same solution for every problem: "Build your own with Linuxcnc") has not had an opportunity to see or use a PCAM machine. Everything from the software and controller to the motors and Z mechanics is highly proprietary. While a retro to LINUXCNC would be possible, it would take a full re-engineering of the drive system and controller, and the mechanics . Cheaper and faster to just build another one. The PCAM is controller loop feedback servo motors, meaning the software knows where the motors are because the position is used by the control software directly. While you CAN do that with LINUXCNC it's just a tad more complex than a normal servo, where the loop closes in the servo driver , not the control software. Chances of you using original servo motors with another control are slim to none. Factor in the Torque sensing backup for ohmic touch off and it means a totally new Z and different methods. When you buy a PCAM its a marriage to that platform,

[robertspark]

It would appear RodW (who has the same solution for every problem: "Build your own with Linuxcnc") has not had an opportunity to see or use a PCAM machine. Everything from the software and controller to the motors and Z mechanics is highly proprietary. While a retro to LINUXCNC would be possible, it would take a full re-engineering of the drive system and controller, and the mechanics . Cheaper and faster to just build another one. The PCAM is controller loop feedback servo motors, meaning the software knows where the motors are because the position is used by the control software directly. While you CAN do that with LINUXCNC it's just a tad more complex than a normal servo, where the loop closes in the servo driver , not the control software. Chances of you using original servo motors with another control are slim to none. Factor in the Torque sensing backup for ohmic touch off and it means a totally new Z and different methods. When you buy a PCAM its a marriage to that platform,

interesting.... I do wonder why people keep buying them?

I mean it makes a good boat anchor 2nd hand when you haven't got the software or it ain't working any more and there is little you can reuse

[Rodw]

Tom, yes you are right I have never looked at a Plasmacam in detail. But people close the feedback loop in the software every day with Linuxcnc. In fact, that is generally preferred. If they are normal analog 0-10 volt servo drives, a Mesa 7i77 includes 6 servo outputs and 6 encoder inputs and is designed for exactly that purpose. Here is a current example from a plasma machine under construction of control box for a servo driven plasma table that closes the feedback loop in LinuxCNC.

cab1.jpg

So that leaves the torque sensing. Normally that is done by sensing the current being consumed by the Z axis motor drive. There are plenty of options for hardware that does this. A chip like the ACS758 current sensor outputs a voltage in thee 0-5 volt range denoting the current passing through it. You could send its output to a Mesa THCAD-5 and connect it to one of the spare encoder inputs on the 7i77. From there it becomes trivial to decode within Linuxcnc.

So I think I'm going to keep an eye out for a boat anchor.

[rdj357]

interesting.... I do wonder why people keep buying them?

I mean it makes a good boat anchor 2nd hand when you haven't got the software or it ain't working any more and there is little you can reuse

If a person purchases a used Plasmacam (from the registered owner with the transfer paperwork completed) that is using the 10+ year old software and the seller of the table does not bother to supply a copy of the software needed to run the table then yes, it's going to take $2k to upgrade to the current software version and get a copy. At that point, the new owner would have current software and access to support. A little research on the part of the buyer before making the purchase would be a good idea and that pretty much applies to any brand of anything a person wants to buy.

If a person purchases a used Plasmacam (from the registered owner with the transfer paperwork completed) that has a current version of Design Edge assigned to the serial number of the machine then the new owner can easily download a current copy of the software to be activated.

If you're buying something for parts to reuse other places then they won't do you much good at all.

[robertspark]

thanks that is interesting ... does surprise me how many people buy things without doing their research

I didn't know this.... even more important for doing your research before purchase

f a person purchases a used Plasmacam (from the registered owner with the transfer paperwork completed) that has a current version of Design Edge assigned to the serial number of the machine then the new owner can easily download a current copy of the software to be activated

[Greavsie66]

I did my research and I could not get a cnc plasma cutter for less than £7000 we got offered our table including hypotherm 45 and stand alone extraction system for £1200. It was working when we got it and we had it up and running cutting all sorts of things on many different metals and different thicknesses.
It would be great to work somewhere that had a unlimited budget to spend on workshop equipment. The nature of the British education system is that we have had years of budget cuts that has a dramatic effect on what we can provide for the kids.
We often rely on the generosity of local companies to supply us with the basic materials and in recent years we have had to ask parents for a voluntary contribution.
Like anything it’s all too easy to criticise a purchase or what a person does from behind a keyboard.
Come and spend a week in my shoes and you will see first hand what it is like.
Fortunately for us we now have it up and running again. I was lucky enough to have a parent come in and help me who works for a local electronics firm. We started with the basics and checked all wires for continuity, then tested all the motors. We then stripped down the control box and found a blown transistor. This was replaced but then we had gantry limit switch error. Again we checked all wires, motors , limit switches and harness. We eventually found one of the small metal pin connectors had been pushed back in to the socket on the green wire on the x axis motor loom.
So after 5 hours we now have it up and running.
If you want to donate to my department for the upgrade to Design Edge I would be more than happy to take your money but for the foreseeable future this is not going to happen so again we are just going to have to rely on the generosity of others to give these kids an education.

[Rodw]

Awesome work. You were fortunate to know someone. Today they would tell you to replace the board and take your money. I have a friend who is good at tracing out a fault like that and repairing it. He always says usually only one component fails and that was exactly your experience.

[rdj357]

I'm glad you got it up and going.