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  1. #1
    Join Date
    Mar 2011
    Posts
    7

    Proma THC problem...

    Hi, I make a plasma 4x4 table.
    Proma Compact THC 150...I bought this unit. I installed on a gecko540 driver with mach3, everlast 80s plasma. It have a cnc plug output, when i plug on thc it give me 0,20 v on 1/50 divider, when i unplug thc i have 2,80 v in plasma output, tryed 1/16 and give me 1.10v fast blinking on thc, unplugged thc give me 7 to 8 v...
    I tryed direct on raw voltage and thc give me 80v, unplugged thc, he give me 115 v +\-...
    I ´m confused... I tryed close or far, it´s same thing...
    thanks for help

    David

  2. #2
    Join Date
    Jun 2009
    Posts
    251

    Re: Proma THC problem...

    You will have to be clearer on what and how you are connecting the THC to your plasma.
    I own and operate 4 Proma THC, one is on an production machine doing 12 h 6 days a week with no problems ever.
    Just as a generall rule,
    be sure you have the polarity right
    be very carefull with plasma, it IS exponentialy more dangerous than a MIG or TIG welder
    use quality cables with good isolation and as close to plasma as posible
    if you have an inverter plsma, voltmeter is not much use due to high frequency
    etc etc
    More info on your setup would help and pictures too.
    Tom

  3. #3
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    Quote Originally Posted by tommylight View Post
    You will have to be clearer on what and how you are connecting the THC to your plasma.
    I own and operate 4 Proma THC, one is on an production machine doing 12 h 6 days a week with no problems ever.
    Just as a generall rule,
    be sure you have the polarity right
    be very carefull with plasma, it IS exponentialy more dangerous than a MIG or TIG welder
    use quality cables with good isolation and as close to plasma as posible
    if you have an inverter plsma, voltmeter is not much use due to high frequency
    etc etc
    More info on your setup would help and pictures too.
    Tom
    yep, it's inverter plasma
    Polarity are ok, test with volmeter for be sure
    I have CNC output on my plasma. 12 pins. i have 2 for trigger, 2 with divider 1/16 or 1/50 with polarity, 2 for raw voltage with resistor installed by manufacturer with polarity, 2 for Arc ''OK" and the other for nothing...
    I have 10 feet shielded wire, and i installed THC on my control box ( Maybe not good... )
    First I tested my output with my voltmeter when I cut sheet metal, give me 2.80V +/- in 1/50 divider output, i tested the raw voltage same time and give me 115V +/-.
    After that, I soldered 2 wire for trigger ( plasma on/off ), and 2 for 1/50 divider in plasma output.
    Plug my wire in THC ( PROMA ) to DV in ( Like the Hyperterm in thc manual ).
    Start plasma and nothing voltage on thc screen... Test wire with voltmeter and give me 0.20V +/-.... unplug THC and voltage come back ok...
    I changed jumper to 1/16 divider and same weird thing, 8v +/- wire unplug of thc and 1.10v thc pluged...
    Raw Voltage cnc output are same thing to...115v +/- unplug Thc, and 80v thc plug in another input each side of proma...
    Its like if the thc eat the voltage...
    I don't understand...

    should I do install THC directly in plasma on RAW voltage inside with no resistance ???
    Maybe my wire are not very good quality for that...
    Thanks for help

  4. #4
    Join Date
    Jun 2009
    Posts
    251

    Re: Proma THC problem...

    It sure skunds like reversed polarity on THC inputs, and since i am not sure if it will damage the THC ( most probably it will), i will ask the manufacturer tomorrow if it has reverse polarity protection built in ( it most probably has) and let you know.
    If you have an phone charger that has a DC 5V output connect that to THC inputs and it should give a reading of 300
    Tom

  5. #5
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    Yet I take very care to put a right polarity.... i will try that...

  6. #6
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    OK, i plug a 5.15V DC in it and give me 253 on the THC Screen...
    What's the problem ?!? Maybe cnc output are like ****...but the plug with my unit are just good size to solder in it... maybe my wire not appropriate ! Yet are shield wire, but are simple wire not multi wire...
    In the manual when I use dv input, i don't supposed to be absolutly very close of plasma, I think...
    Thanks for help

  7. #7
    Join Date
    Jun 2009
    Posts
    251

    Re: Proma THC problem...

    I checked with the manufacturer and there is protection built in, so all is good. The max. current draw on the inputs is 1mA.
    Now change the wires or even better connect 2 plain isolated wires to 1/50 output and start plasma.
    If all else fails, connect it to output terminals.
    Personaly i have 4 of Proma THC and know of 2 other persons having the same units working absolutely without a hitch ever, so i am confident you will get it working and enjoy it.
    Regards,
    Tom

  8. #8
    Join Date
    May 2007
    Posts
    250

    Re: Proma THC problem...

    Hello Friend,
    The good THC and quick response. It is produced from thailand manufacturer. It can link with mach3 software with good action. The prices is not expensive.
    If anyone interested in the good THC,pls contact me at [email protected] or CNC PLASMA MACHINE
    Nesting of extracnc - YouTube

  9. #9
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    thanks mongkol, I keep in mind.

    I try to wire directly on output 1/50 inside the plasma box tonight, no wire for nothing ! i will see if are ok like that...

    Thanks again

  10. #10
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    I cut the 1/50 2 wire just behind the cnc output of plasma and i plug directly on the thc, and same thing.... i cry....
    I'm very disapointed of the results....
    yet all are supposed to be ok for good result...
    Maybe plug directly on the output, just before enter on the cable...

    I plug directly on the electrode like old school and read OK !!!
    But are very more difficult to make a plug for all that...
    need 8 input on plasma ( 4 for in and out of thc +2 for 12V, and 2 for trigger on/off... )

    If the output of plasma was OK to drive the thc, only need 4 wire to plasma...

    Which ARC OK are better, proma thc or plasma signal ?
    i think are Thc, normally I think are better place to know when are ok...

    in description of my Everlast 80S
    ( Features & Benefits: Easy starting with Blow Back Pilot arc allows easy cutting of rusty and painted metals)

    Are not supposed to be Hard for Electronic, Maybe JimColt can confirm that for me....

    Thanks

  11. #11
    Join Date
    Oct 2010
    Posts
    156

    Re: Proma THC problem...

    My plasma cutter's 1/50 output could not provide enough to run the Proma. Connecting a meter to the 1/50 output read fine, but the Proma must draw too much and the voltage dropped enough to not be useful (below 40V (converted)). I ended up buying a different voltage divider and wired it in the cutter which allowed me to run a seperate wire into my controller where I mounted the Proma.

    Otherwise - Direct voltage with the Proma mounted close to the cutter.

    HTH
    Paul

  12. #12
    Join Date
    Jul 2005
    Posts
    2415

    Re: Proma THC problem...

    There are several problems with trying to use a 50:1 divider:
    1. the input impedance of the reading circuit needs to be very high to no load the divider network. Something in the range of meg or more.
    2. At 50:1 every .020 volt of change is 1 volt in the reading. 20 mv. A few feet of wire will pickup 100mv or more of noise. The connection to the THC must be VERY short
    3, In a shop with plasma cutters, arc welders and other noisy equipment you have to design everything to be EMI and RFI resistant.
    4. Running Raw Arc volts outside the plasma is not only unsafe (160VDCat high current is lethal) but makes any noise problem worse acting as a transmitter antenna.

    We resolved the 50:1 issue on our higher end DTHC by designing a pickup module that mounts at the Plasma and takes the tiny voltage across a short shielded cable and changes it to a constant amplitude digital signal that is isolated and noise immune. You can run 50 ft away from the plasma with no problems. All interface to the plasma from the DTHC is via one CAT5 cable. With the divided volts being isolated the digital interface back to MACH (or LinuxCNC) via the parallel port can be direct and high speed.

    We have a hobby grade THC (LCTHC) that comes with a separate voltage divider card (ratio is closer to 10:1 than 50:1 for better noise immunity) and allows the control head to mount at the operators station. Single rotary encoder for all settings. Dual line LCD readout shows preset and actual volts along with ARC OK indicator and UP DOWN arrows. We don't sell a lot of them because when the customer compares the three models of THC we offer they almost always choose the more advanced and automated models

    TOMcaudle
    www.CandCNC.com
    Home of MP3100 DTHCIV...fastest MACH based THC on Earth!

  13. #13
    Join Date
    Mar 2011
    Posts
    7

    Re: Proma THC problem...

    **** torchhead! When I asking you to make me a soumission, you wrote me are about 800$ for THC... just for that I verified another solution...
    I'm just look your THC comparaison and I see the price are same....
    anyway, since 6 month I pay around 4500$ for make my table like I like !
    I try to work with my actual equipment, after a few month of testing and running, i will check to upgrade my setup..

    Thanks for help buddy...

  14. #14
    Join Date
    Jul 2005
    Posts
    2415

    Re: Proma THC problem...

    You need to check the website and understand that the DTHCII and DTHCIV are EXPANSION Modules for our MP3000/MP3100/MP3500 line of advanced BoB. They are not just THC products where you have to have a BoB and figure out how to do the interface. The MP3000 plugs into the parallel port (or Ethernet on the MP3500) and it comes with a separate interface card (which can be mounted up to 20ft away from the MP3000 that has screw terminals for 5 axis and a 26 pin IDC header for a cable to plug directly to a G540 driver.. The DTHC IV uses our new C3Bus 4 port hub (USB to RS485) to pass slower speed data (screen readouts and settings) . There are NO knobs, buttons or readouts on the DTHCII or DTHC IV/ Everything is on the screen in MACH and settings can be either stored locally of if you use SheetCAm our POSTS (free) let you store all of the settings in the JOB (G-Code). The MP3000 has lots more I/O than a conventional BoB so you have plenty of inputs for all of the homes AND the THC signals. All the advanced features take the MP3000 interface to MACH so the prices you got before were for the MP3000-DTHC or MP3100-DTHCIV products.not just the DTHC section.

    Tell you what I will do: I will give you $100.00 trade in on any other MACH based THC (including the Promo unit) against any of the MP3000 series with DTHCII or DTHCIV . I will extend this offer to any of the CNCZone members. I will try to get it on the MP3000 webpage this weekend. This is a special deal and will be for a limited time. This does not extend to the LCTHC (which is already cheaper than the Promo )

    TOMcaudle
    www.CandCNC.Com
    Where Engineering meets Excellence!

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