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IndustryArena Forum > CNC Electronics > Gecko Drives > Red "fault" light is lighting on my G540.
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  1. #1
    Join Date
    May 2006
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    309

    Red "fault" light is lighting on my G540.

    It has worked until today when I coupled a rotary drive stepper to it. I have tried to remove the A-axis wire from the drive, but it´s still the same. I can reset Mach3, but when I push the buttons, only the numbers on the screen are running but not the steppers.

    What may be wrong?

  2. #2
    Join Date
    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    when the RED LED is on all 4 G250 stepper drivers are disabled
    ( the signal that turns the GREEN LED on also enables the stepper drivers )

    its possible a faulty connection to the A Axis has damaged the A Axis driver and is triggering the E-stop / over current circuit

    I would disconnect all motors and check you can clear the fault ( just in-case its not the A axis that's the problem)
    if you then get the green light , connect one motor at a time until you trigger fault so you know what is the problem

    if the RED LED is on with no motors connected
    contact Geckodrive.com
    they will probably talk you through the disassembly of the G540 and removal of the four G250
    drivers to find the faulty one that need repair / replacement
    that will enable you to use the G540 as a 3 axis driver while your waiting for the fourth G250

    ( the G540's case is just clipped together the motherboard with all of the external connectors is plugged onto the four G250 boards that are screwed to the lower half of the case )

    Click image for larger version. 

Name:	g540coverless.jpg 
Views:	1 
Size:	58.1 KB 
ID:	411950
    picture taken from geckodrive web site

    alternatively they will give you instructions for you to return the G540 for them to test

    John

  3. #3
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    I removed all the wires, but the red light was there yet. I have also removed the paralell port cable, but still the same. Can it be that the power supply is damaged and doesn´t deliver enough current?

  4. #4
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    with the parallel printer cable disconnected you will need to switch the charge pump to off ( switch to the right of the printed logo on the G540)

    what powersupply are you using ?
    with no motors connected what is the voltage you measure at the power supply terminals ?

    John

  5. #5
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    The charge pump has always been off. The voltage is 44V and when I took a quick on/off measurement of the current, it meassured 12A, so it should be more than enough. If I open the black box, can I then find out more? Will it be possible to remove some of the drives from the others in order to find the reason?

  6. #6
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    44V is OK (it is within the 18 to 50V limits )
    with no motors connected you should not see 12A going into the G540 even taking into account current waveform will cause an inexpensive multimeters reading to be inaccurate

    with the cover off you will be able to unplug the main board from the four drivers and test the board on its own

    you will see each G250 driver is fastened to the base with 2 screws -
    note the G250 FET transistors and voltage regulator is only insulated by the black anodised coating, be carefull you don't damage the coating

    assuming the main board tested OK
    remove 3 drivers plug the main board onto the remaining driver
    if that works add another driver and retest
    repeat until you find the faulty driver (or all 4 axis are working)

    john

  7. #7
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    I didn´t measure the input current to the drives, but the short cut current of the power supply. I have now removed the drive for the A-axis and the green light came back, so I think something must have been wrong with the rotary stepper motor or maybe the wiring. Are there any ways to troubleshoot that case?

  8. #8
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    have you have used the rotary axis stepper motor before ?

    I expect either the cable has been crushed so 2 wires shorted
    or you have a wire break that could be intermittent with just the insulation holding the broken ends of the wire together

    with the power on ,
    the back EMF generated when a motor coil is disconnected is high enough to destroy the stepper driver H bridge transistors

    while you can have a wire break any where
    the odds are greater where the wires exits the 9 way plug or enter the motor

    with a basic multimeter its not always easy to see the increased resistance of a dry joint
    when the resistance of the cable and motor winding is a few ohms and can be comparable to the contact resistance of the meter probes

    several times at work
    I have had inconclusive resistance measurements while checking multicore camera or audio cables

    cutting the last inch or two ( 25 to 50mm) off each end and soldering the connectors back on solved the problem

    John

  9. #9
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    I used this motor several years ago, but with another driver and I have resoldered the wire to the gecko plug after that, so maybe I have done something wrong there. The wire has also a middle plug connection near the motor which has been disconnected these years, so maybe some of the pins in this plug have been covered with an oxidation.

    Can I test the motor and the wiring with a stable dc current in any ways?

  10. #10
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    do you have the data for your motor ?

    do you have a bench power supply with a variable voltage output and current limiting ?

    stepper motors will not run when connected to a DC supply

    what you can do is either apply the DC voltage as on the data sheet or label to one of the motor coils in turn and measure the current that flows
    or set the power supply current limit to the current stated in the data and measure the voltage across the coil

    for example if the motor data gave the coil resistance as 2 ohms the current as 3A and voltage as 6V

    connecting a motor coil to 6V DC will result in a current of 6/2 = 3A


    if the power supply is set to provide a constant current of 2A the volt drop across the motor coil will be 2 x 3 = 6V



    using a spare 9 way socket to make it easy to connect to the 9 pin plug on the cable
    you can measure the voltage across the motor coils and then at the 9 way D-type plug

    the volt drop across each coil and each pair of wires should be the same

    in addition you will need to check for short circuits between pins 7 & 8 (coil B- and A+)
    and pins 1 to 5 and pins 6 to 9

    did you fit heat shrink sleeving in the wires to insulate the terminals ?

    Attachment 412060

    if you have used a single resistor to set the motor current its easier to insulate the terminals than trying to solder 2 resistors in parallel

    one possible problem you can have when you solder stranded wires to the bucket terminals on the 9 pin plug
    solder can wick up inside the wire and when its flexed the wires break where the solder stops


    John

  11. #11
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    Motor label: KL23H251-24-8B When I tested the wires there was a difference between the coils. I could light a led with one of the coils but not with the other, and I have tested the wires close to the motor, so I believe it must be a damage inside the motor. There was also resistance difference.

    I have another new larger motor: 57BYGH78-401B 1.8 degr. 2.8A 1.8 N.m. Do you think I can use that with the Gecko driver? And do you know where I can buy a new driver for best price?

    ----------------------------
    Edit:
    I used the 8 wire motor in serial connection with the red/yellow and black/orange wires shorted and after cutting of these wires, the motor runs more smoothly and I got a light on the led at that coil that didn´t light before. When I short the red/yellow wires, the same problem occurs, so I found that the motor is wired with wrong colours compared to the specification at http://www.kelinginc.net/KL23H51-24-8B.pdf

    I have found that the red/yellow and green/blue are connected to each of the coils and my problem is now to find out which of them are a+ and a- ...

  12. #12
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    Re: Red "fault" light is lighting on my G540.

    if this is how the motor is connected

    Attachment 412082

    the motor should work

    unless your following instructions to make one of a number of identical machines

    swapping A+ and A- or B+ and B- will reverse the direction of the motor
    easily corrected in software if your using Mach 3 or similar to avoid resoldering the wires

    just make sure you don't mix the A and B wires

    John

  13. #13
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    That´s how it was connected, but when I connected the red and yellow wires together, it made a shortcut to one of the coils because these wires are the end wires of that coil on my motor. So I assume that my motor is wired with faulty colors compared to the wiring diagram which may have been caused by poor workmanship at the factory.
    --------------------
    Edit:
    I have tested the wires again and found that the two coils with red, blue, yellow and green wires all interacts with two other wires, so there must be a shortcut between the coils inside the motor which means that the motor is damaged. So I have to give it a try with the other larger sized motor.

  14. #14
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    After changing to a new motor and new driver, I got the motor to run but with a very strange sound (like fast ticking). When I tried to tune the pot on the driver in order to fix it, it looks like something went wrong and the force to the motor died and both the green and red leds are lighting on the G540 box. I pulled out the wire to the motor, but the red light is still on. The 3 other motors works normally.

  15. #15
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    going by the circuit diagram for an early version of the G540 that I found in an old post on cnczone

    Attachment 412450

    I don't see how 3 axis can work with the RED led on
    as the enable signal to the G250 driver boards is used to switch between the red & green LED

    what happends if you remove the faulty G250 driver ?
    I guess its possible is pulling the enable signal down so there is a voltage across the red LED as well as the green LED

    are you sure the motor was connected correctly ?

    I would email or call Geckodrive.com

    John

  16. #16
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    I´m not sure but do you think it will be possible to get a motor to run in both directions if it´s wrong connected? I will try to remove the driver later and see what happens then.

  17. #17
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    2083

    Re: Red "fault" light is lighting on my G540.

    some times when a stepper motor is wired incorrectly
    at first glance it will look like its working

    you would hope the motor conforms to a standard colour coding of the wires

    assuming the new motor is another 8 wire motor like the KL23H51-24-8B
    Attachment 412462

    then you could have odd results if you either mix the pairs of coils
    for example connecting the red/blue coil to the brown/black coil and
    yellow/green coil to the orange /white coil

    wiring two coils in anti-phase
    for example connecting blue and yellow together and red & green to the driver
    would have dramatically reduced the inductance to less than the minimum 1mH
    resulting in an over current

    John

  18. #18
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    May 2006
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    309

    Re: Red "fault" light is lighting on my G540.

    The new 57BYGH78-401B stepper motor was a 4 wired bipolar motor. I connected it wrong by connecting the -a to +a and visa versa, and did the same with the b wires, so I didn´t get the motor to run before I changed the settings in the Mach software. Is it possible to overload the drivers that way? Could I have done something wrong in the settings? The motor is rated with a current at 2.8A, so I mounted a 2.7 kohm resistance to the plug pins.

    I have now connected a new driver and now only the green led is on, but I´m afraid to try again with the same motor before I know what it was that failed.

  19. #19
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    Mar 2007
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    2083

    Re: Red "fault" light is lighting on my G540.

    swapping A+ with A- and vise versa and / or B+ with B- and vise versa is not going to damage the driver
    just change the direction the motor turns if you swap one pair of wires
    a 2K7 resistor is close enough as it will set the motor current to 2.7A

    the problem is if you connect A+ to B+ and A- to A- for example

    if you get the mach3 settings wrong your not going to damage the driver but its possible to step too fast and stall the motor

    so far I have not found the 57BYGH78-401B data

    with a multimeter set to ohms you should be able to test the motor to find the two pairs of wires


    John

  20. #20
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    May 2006
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    Re: Red "fault" light is lighting on my G540.

    I didn´t connect a to b, but I´ve found that maybe one of the wires had a loose connection. Could that be a possible reason?

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