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IndustryArena Forum > MetalWorking Machines > Okuma > Okuma LB15 110 Alarm A
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  1. #1
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    Okuma LB15 110 Alarm A

    I have one Okuma LB15 year 1998 with OSP 5000 L-G.
    When i was using the machine and did the first cut it went to deep in the material so the machine stopped imidiatly the spindle stopped and the machine came up with the alarm: Alarm 110-A spindle unit 1

    I restarted the machine after the crash and when i started the machine again the Alarm: 110-A spindle unit 1 appeared. I then get an alarm on the digital AC unit (printed circuitboard) AL-12 alarm.
    as soon as i start the machine evrything works exept when im trying to start the spindle then thoose alarm appears.
    No fuses has blown evrything is good, The main spindle servo engine has no errors.

    AL-12 alarm on the printed circuitboard meaning is current DC-link is to much.
    I have checked DC power volt check on PCB check terminals. Where it should be 24V i get 26.4V.
    That is the only error i find. What does it mean? what is the problem?


    Printed circuit board: A20B-101-0120 edition number: 16ER 927R
    Reference of drive: A06B-6055-H208
    Reference of rom: 9603

  2. #2
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    Re: Okuma LB15 110 Alarm A

    How long are you leaving the breaker off after powering down? You will typically need a couple minutes for the drive to drain off power and properly reset.
    Experience is what you get just after you needed it.

  3. #3
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    Re: Okuma LB15 110 Alarm A

    Hi I have waited from 10min to several hours before I have to start the machine and always the same result, as soon as I start the spindle the alarm comes.

  4. #4
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    Re: Okuma LB15 110 Alarm A

    Could there be a fault on the printed circuit board?
    The card looks good, no burned components, everything looks very good.
    But there can still be something wrong with it.

  5. #5
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    Re: Okuma LB15 110 Alarm A

    Could be a drive board problem. Have you tried starting the spindle in reverse? Circuits may be slightly different when reversing. Are all phases showing good voltage? Sometimes dropping one leg (fuse?) can not generate other alarms, but drive may detect it.

    DC Link that you mentioned is not the DC power supply I think but may be the power "bus" for the drive unit to the motor.

    Of course be careful testing any voltages!
    Experience is what you get just after you needed it.

  6. #6
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    Re: Okuma LB15 110 Alarm A

    Have tried to start forwards and backwards
    Same alarm.
    The phases are good.
    The motor is 100% ok. Had an electrician here who measured phases and motor.

    What can it be on the drive board?


    How can I troubleshoot the DC link?

  7. #7
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    Re: Okuma LB15 110 Alarm A

    Attachment 480050Attachment 480052Attachment 480054Attachment 480056Attachment 480058Attachment 480060


    Uploads some pictures from the control cabinet.
    A green LED lights up and the digital is set to 00000
    then the machine is running.
    But as soon as you press the spindle start so
    alarm AL-12.

  8. #8
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    Re: Okuma LB15 110 Alarm A

    did you performed a simple test of IGBT modules of the spindle drive?

  9. #9
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    Re: Okuma LB15 110 Alarm A

    Hello
    What do you mean by IGBT?
    What is it.

  10. #10
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    Re: Okuma LB15 110 Alarm A


  11. #11
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    Re: Okuma LB15 110 Alarm A

    Attachment 480826Attachment 480828

    Really need help.

    Has replaced IGBT with new ones.
    Have measured the diodes they are ok.
    Post pictures so you can see what I change to new.
    Still gets the same alarm.
    Is there any way to troubleshoot the colored circuit board so that other errors can be ruled out?
    Want to be as safe as possible before I buy a new colored circuit board.

  12. #12
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    Re: Okuma LB15 110 Alarm A

    These aren't IGBTs- 100L6P41 is bridge rectifier, and MSG100L41 are thyristor modules. Completely different type of semiconductor device and very specific to test (multimeter isn't a way to go here). Is the main drive motor DC? Can You take a photo of base unit where power components are located?
    There should be somewhere a manual on this FANUC drive- what is written in alarm list on that specific alarm code? Usually all these troubles with drives start when power supply starts to get wrong (bad electrolityc capacitors are usually the case, then there is voltage ripple or in worst cases caps go short and burns out rectifier and power stage ).

  13. #13
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    Re: Okuma LB15 110 Alarm A

    Ok-I have read first post- DC-link current fault. It is possible some current transformer (or Hall sensor if such is used there) is damaged (or it's circuit). Check all wires and condition of plugs.

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    Re: Okuma LB15 110 Alarm A

    Attachment 480914Attachment 480916Attachment 480918Attachment 480920Attachment 480922Attachment 480914Attachment 480924

    Has taken a picture of the engine.
    And picture of the explanation on A110 alarm and AL-12 on printed circuit board.
    Has checked all cables and connectors that are to the spindle drive unit. And everything looks good.

  15. #15
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    Re: Okuma LB15 110 Alarm A


  16. #16
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    Re: Okuma LB15 110 Alarm A

    Did you check all cement resistors?
    "Imagination is more important than knowledge."

  17. #17
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    Re: Okuma LB15 110 Alarm A

    They look good but have not measured them.
    The circuit board looks good both front and back nothing burned and nothing that seems to have gone hot.

  18. #18
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    Re: Okuma LB15 110 Alarm A

    You should check all connections and components that are connected to those big electrolythic caps at the bottom. At top of the drive should be located IGBT transistors (it seems this drive has regenerative braking, so thyristors at bottom of the base could be for that part). Not in all cases bad semiconductors will be burned out- as the crystal in them degrades by the time, they rapidly change their properties- seemingly good looking IGBT transistor could switch on/off slower, could get into linear mode (then they start to overheat) or in worst case they simply lock down like thyristor (then its impossible to switch it off. Again- they overheat and become permanently damaged). Try to check also those big electrolytes- they sometimes give a lot of headaches. Remember that they can hold a charge (yes- I know there is ceramic resistor, but even with it cap still can keep some voltage accumulated to create sparks).

  19. #19
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    Re: Okuma LB15 110 Alarm A

    Thanks
    Will check this out.

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