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  1. #1
    sushrut is offline Plastic
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    I wish to get some quick help to get working my CNC machine which stopped turning ON all of a sudden today

    After turning ON, both of my Fanuc 0MB mill and 0TB turning machines, connected to same transformer have been showing alarms 401, 414, 424. This is happening all of a sudden as it was only about 5 days ago when both the machines were working fine.

    I read forums, the manual, and read the dignostic bits 721 and 720 to find that the values were 100.

    I checked up on the PCB of the servo amplifier and an LED labeled as "DC" is glowing RED.

    I feel that its probably the transformer which is the culprit and is giving out high voltage to my machines.

    The transformer has dials reading output voltage, and 2nd phase of the three reads 500V almost when rated voltages are 415 volts per phase.

    Is it that this IS THE VERY problem? Am I correct in deciphering the situation and concluding that high voltage in transformer is the issue? Or is it something to do with the machines?

  2. #2
    machtool is offline Titanium
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    Are you sure your Diagnostics 720 & 721 were showing 00000100 and not 00001000.
    Bit 3 is HVAL (Over voltage)

    I'd think at 500V, and both machines, showing same alarms on all the axis..Its your power supply rather then the machines.

    I wouldn't worry about your alarms 414 & 424.

    They will clear up when you get rid of 401 VRDY Control ready, Your not getting that because of your HV alarm

    Cheers Phil.

  3. #3
    sushrut is offline Plastic
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    Thanks Phil for the reply.
    Even i was wondering it should have been 1000 and not 100. but i checked many a times and it is 100.
    Further when i opened the panel and saw on the PCB, there are 5 LEDs corresponding to HV, DC, OH etc etc.. even there the DC LED is glowing ( idont know what DC means) and HV LED which is for high voltage is NOT glowing..

    I still feel it has to do with the power supply.. what say?

  4. #4
    machtool is offline Titanium
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    I was worried you were going to tell me that. Your Diagnostics 720 & 721 and DC led are indicating a DCAL alarm. In Fanuc speak. ďAn alarm of the regenerative discharge circuit has occurredĒ.

    Thatís typically a fault on the transistor module in the drive. The chances of that happening, on several axeís on two machines at once, are fairly remote. Unless you had some catastrophe like a lightning strike or a H.V line fall on your street wiring. Which also cooked you transformer.

    The short and sweet of it, if your measuring 500V, on a service meant for 415V, your more than %20 over voltage. And a wild un-balance given that itís on one phase. Fanuc will stipulate + / - %10. And in my experience, you donít have much window for margin after that, before you start to get faults.

    I still feel it has to do with the power supply.. what say
    Thatís simple. Regardless if this is the cause of the fault or not. You cant knowingly continue to feed the machine 500V. You need to address this first. Iím hoping that will do it for you.

    Secondly, being Fanuc, the machines should be 200V or 220V. So Iím thinking there will be secondary transformers on the machines for this. The bigger incoming voltage will take those percentages higher.

    Regards Phil.

  5. #5
    sushrut is offline Plastic
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    Hi Phil
    thanks a lot for all the help

    we fixed the power transformer and bang.. things fall in place.. no more alarms, nothing..

    thanks for all the help.. it was the transformer giving unnecessary high voltage the culprit.

    Sushrut

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