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IndustryArena Forum > CNC Electronics > Gecko Drives > G540 always in fault - red LEDS - strange voltages
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  1. #1
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    G540 always in fault - red LEDS - strange voltages

    My G540 was working just fine until it decided not to. It doesn't have that much use on it. Here's what is happening:

    1. Red "fault" LEDs illuminate when power is turned on.
    2. Multimeter probes between pin 10 and 12 show open and closed circuits when the E-stop button is switched. Button is working.
    3. Disabling the charge pump doesn't change the results. I tried this with and without the DB25 connected.
    4. Screen in Mach 3 always shows "external e-stop requested"
    5. Multimeter probes between pin 1 and pin 12 show a small fraction of a volt. (limit switch connected and grounded)
    6. Multimeter probes between pin 2 and pin 12 show a small fraction of a volt. (limit switch connected and grounded)
    7. Multimeter probes between pin 3 and pin 12 show a small fraction of a volt. (limit switch connected and grounded)
    8. Multimeter probes between pin 4 and pin 12 show 48V!!!!!!!!! This is without any wire connected to pin 4 input. Is it supposed to be 48V? Was expecting 5 or 10V?
    9. Multimeter probes between other pins show 5V as I expected.
    10. Multimeter probes between pin 11 and pin 12 show 48V as expected.

    The only thing I recently changed in my setup was adding a .1uF ceramic cap to each of the 4 inputs (pins 1 thru 4) and tying them all to pin 12 ground. I've removed the capacitors since then, but no luck getting back to my original working condition.

  2. #2
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    I had a similar problem few hours before. I connected the Estop Ground to common ground of power supply. Make it sure that you have connected Estop ground at Pin-12.
    In MAch3 also check wether your Estop is "Active Low" or Active High..
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

  3. #3
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    Another thing to test is to disconnect one motor at a time while powered down and try the start up.

    I had one loose wire inside one of the plugs I installed (db9) and that was what lead me to pinpoint the trouble.
    Lee

  4. #4
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    Also check your Estop button. Is it down?
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

  5. #5
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    I was sure it was a bad DB9 cable, but turns out my problems don't lie there.

    I pulled out all the wires, and all that is connected right now is:
    Terminal 10 jumpered directly to Terminal 12 (no E-stop button in-between). Continuity check between the two terminals checked out good.
    Terminal 11 connected to +48 VDC supply
    Terminal 12 connected to ground and to Terminal 10

    Charge pump is disabled.

    Red fault LEDS come on when power is applied.

    I followed steps 1-3 in the G540 manual, and I should have a green light at this point, which I don't.

    What is happening?

  6. #6
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    I'm not sure if a blown fuse inside will still show a red fault or not, but you can take the cover off and do a continuity check on it.
    If it is good, then you might want to contact Gecko about repairing it for you. I have had a few different drives from them repaired or replaced for free. I think they will automatically give you one free repair if your fault.
    Lee

  7. #7
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    I'll have to get in touch with them I think.

    I just removed the G540 from my CNC machine and connected it to another power supply, with the minimum connections required on Terminals 10, 11 and 12, and I still got the same result.

    I'm going to open it up now and take a look.

  8. #8
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    Look what I found after I opened up the G540...

    It appears that a clipping from one of the leads got wedged between two pins of the MOSFET. I removed it, and tried all the minimum connections again. This time, no red LED, but no green LED either. The 4 LEDS near the axis trim pots come on (as before) and are illuminated red. I hooked up all the other terminals and powered up Mach 3 and my CNC, but I still have no green LED, and I'm still getting the "external E-stop requested" message. I think something on the G540 board got fried.

    Thoughts?

    Click image for larger version. 

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  9. #9
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    This is from the troubleshooting chart that you have probably seen.
    SOLUTION: Verify that the power supply is plugged in correctly to the 12-PIN TERMINAL BLOCK. If it is and power is applied with no LEDs being lit up, you have most likely had the fuse blow open. To check the fuse you must first remove the cover. The fuse is located by the 12-PIN TERMINAL BLOCK on the underside of the motherboard; you can pull the motherboard off of the G250 drives to access it. Next, use an ohmmeter to check for continuity on the fuse, which looks like a green 1/4W resistor. If the fuse it destroyed you may contact Geckodrive for replacement fuses or order spares online with part number F23118-ND from Digikey.
    Lee

  10. #10
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    Yup, I checked that one when I had opened it up. Fuse is still good. Thanks.

  11. #11
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    I think your MOSFET IRF540 is damaged. My suggestions:
    1- Send the photograph to Gecko personals i.e Marcus etc and ask their opinion.
    2- If you do not want to send the drive to Gecko then replace this MOSFET. Its readily available in Market. Make it sure you purchase IRF540 instead of IRL540. Further ask the Gecko of replacement of this MOSFET.
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

  12. #12
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    I was reading about MOSFETs and it seems that shorting the gate and drain (as what happened in my situation) won't damage the MOSFET? I'm not 100% sure, but if this is the case then damage is somewhere upstream or downstream of the MOSFET. I can easily swap it out and am comfortable with solder rework, but I don't want to be messing with the original board unless I hear from Gecko. I contacted their tech support thru email. We'll see what happens in the next few days...

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