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  1. #1
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    DC Servo Vibrates on Fanuc 6M

    I have several problem with fanuc 6MB at Yamaguchi MC
    1. when I move X axis to (-) direction it goes smooth. but if I move to opposite (+) direction, the servo vibrates so hard.
    2. its happen to Z axis too with contrary case. when it goes up (+ direction) looks smooth. but if I move to minus direction, it just move a little then alarm comes up. (430 Z Servo)

    I've compared whole parameter with Y axis with normal condition,but no luck. its still the same. Maybe I miss some parameter

    What should I check to fix that problem?
    Thanks in advance

    PS : DC Servo Motor type 5M with VCU A20B-0009-0320

  2. #2
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    where is Al The Man and Dan Fritz ? I need you here ASAP

    I swap both servo and drive with Y axis but the problem still on X axis
    I checked the DIAG 713 bit 4-5 works fine for Pulse coder

  3. #3
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    Servos vibrate.

    We had similar problem with our 6M Pratt & Whitney VMC machines. We discovered that if you can, remove the servo end cap. This should expose the servo encoder. Don't confuse with the encoder on the ball screw. Spray servo encoder with electronic cleaning spray available at Radio Shack or Best Buy. Cycle servo manually several times. Worked for us.

  4. #4
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    Quote Originally Posted by parametric.ms View Post
    where is Al The Man and Dan Fritz ? I need you here ASAP

    I swap both servo and drive with Y axis but the problem still on X axis
    I checked the DIAG 713 bit 4-5 works fine for Pulse coder
    First check +15 volt -15 volt and +5 volt on your Master PCB. If it Ok may be you had problem with master PCB. The main problem is in hybrid IC APC06

  5. #5
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    Quote Originally Posted by greenery_fr View Post
    First check +15 volt -15 volt and +5 volt on your Master PCB. If it Ok may be you had problem with master PCB. The main problem is in hybrid IC APC06
    Is it Freq to Voltage Converter IC? where is the location on master PCB?

  6. #6
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    Quote Originally Posted by 3d GEORGE View Post
    We had similar problem with our 6M Pratt & Whitney VMC machines. We discovered that if you can, remove the servo end cap. This should expose the servo encoder. Don't confuse with the encoder on the ball screw. Spray servo encoder with electronic cleaning spray available at Radio Shack or Best Buy. Cycle servo manually several times. Worked for us.
    Like I describe, seems look no problem with pulse coder. It works at minus direction smoothly. But I'll double check just for make sure

  7. #7
    On the older machines with DC motors, I found that in the case of vibration, cleaning the brushes and armature usually solved the problem. The brushes are located at 90 degree increments around the motor housing under rubber caps. Keep track of which hole the brushes came out of. Blow them off with clean dry compressed air and then clean the armature with a pencil eraser. If it's the problem, the eraser will come out black and sooty. Blow thru the brush holes with compressed air, but try not to breath the dust.

  8. #8
    This is an A06b-6047-hxxx servo drive correct? Are both servos identical?

  9. #9
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    Quote Originally Posted by ITT-Student View Post
    This is an A06b-6047-hxxx servo drive correct? Are both servos identical?
    3 axis are identical. A20B-0009-0320. I already swap whole unit (drive & motor) X to Y but had no luck still vibrating on X. I haven't swap with Z axis

  10. #10
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    Quote Originally Posted by mike-at-thorn View Post
    On the older machines with DC motors, I found that in the case of vibration, cleaning the brushes and armature usually solved the problem. The brushes are located at 90 degree increments around the motor housing under rubber caps. Keep track of which hole the brushes came out of. Blow them off with clean dry compressed air and then clean the armature with a pencil eraser. If it's the problem, the eraser will come out black and sooty. Blow thru the brush holes with compressed air, but try not to breath the dust.
    the 1st thing that I done was disassembled motor from ballscrew. checked the carbon brush, remove and clean armature from dust with clean dry compressed air.but nothing change even I swap the motor

  11. #11
    So the problem didn't move with the drives or motor? If this is the case then maybe you have some "noise" near the axis's or cabling? Do you have manuals on the fanuc 6?

  12. #12
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    Quote Originally Posted by ITT-Student View Post
    So the problem didn't move with the drives or motor? If this is the case then maybe you have some "noise" near the axis's or cabling? Do you have manuals on the fanuc 6?
    yes precisely... did you mean noise that affected to command signal? I have the manual doc with scan quality

  13. #13
    Quote Originally Posted by parametric.ms View Post
    3 axis are identical. A20B-0009-0320. I already swap whole unit (drive & motor) X to Y but had no luck still vibrating on X. I haven't swap with Z axis
    You do realize that A20B-0009-0320 is just the top board on the servo amp, just swapping these without the base of the drive could leave the problem where its at if there is a problem with the power transistors or bridge rectifiers leaking AC.

  14. #14
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    Quote Originally Posted by ITT-Student View Post
    You do realize that A20B-0009-0320 is just the top board on the servo amp, just swapping these without the base of the drive could leave the problem where its at if there is a problem with the power transistors or bridge rectifiers leaking AC.
    Did I mention whole unit? which mean top board include base of drive.
    I'm not really sure there's a problem with DC drive (TM,DM). There is something with voltage command. but how come?

  15. #15
    Community Moderator Al_The_Man's Avatar
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    So If I have this right, you have swapped the drive and the motor and it stays with the X?
    Did you try the motor disconnected from B.S.?
    Do you have resolvers on the motor?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  16. #16
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    Quote Originally Posted by Al_The_Man View Post
    So If I have this right, you have swapped the drive and the motor and it stays with the X?
    Did you try the motor disconnected from B.S.?
    Do you have resolvers on the motor?
    Al.
    yes thats right Al, still on X at + direction.
    what do you mean with BS? ballscrew? I've tried with no load, just lay on the floor. the motor use Pulse coder 2000 ppr

  17. #17
    Community Moderator Al_The_Man's Avatar
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    Disconnect for the ball screw?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  18. #18
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    yes of course sir.. I've tried with no load, just lay on the floor. the motor use Pulse coder 2000 ppr

  19. #19
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    Hi could you send me your the scanned manual?
    I have this problem once check the encoder coupling if you have some backlash between the encoder and the motor, the motor vibrates.

    Carlos

  20. #20
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    Quote Originally Posted by parametric.ms View Post
    yes of course sir.. I've tried with no load, just lay on the floor. the motor use Pulse coder 2000 ppr
    Greeting! I have same problem with X axes DC motor. Do you solved problem?

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