Thread: HCAL, Servo 401 Fanuc 6mb

Started 1 month, 1 week ago by Andy Fritz

Hi Folks, I have a Hitachi Seiki VA35, with Fanuc 6 mb, DC servo amp A06B-6047-H003 and top pcb A20B-0009-0320, model 10 Yellow Cap DC motor which has given me lots of grief over the years dishing out various problems at random. The latest was servo error 401 on start up with HCAL on X axis. I have had those before on Z and then fixed it by replacing the 1"x1" black opamp on the servo amp ...

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Reply 1: HCAL, Servo 401 Fanuc 6mb

Al_The_Man replied 1 month, 1 week ago

I just fixed one with identical 401 error problem, no error until an attempt to move. This turned out to be a build up of carbon on the brush housing and causing tracking to ground when power applied, fortunately I had a stripped motor that had a good brush holder assembly. I would remove the power connector at the motor or drive end, and with the lowest resolution on the hand wheel, rotate the...

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Reply 2: HCAL, Servo 401 Fanuc 6mb

Andy Fritz replied 1 month, 1 week ago

Originally Posted by Al_The_Man I just fixed one with identical 401 error problem, no error until an attempt to move. This turned out to be a build up of carbon on the brush housing and causing tracking to ground when power applied, ...

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Reply 3: HCAL, Servo 401 Fanuc 6mb

Al_The_Man replied 1 month, 1 week ago

The armature cables are typically in 2 pairs, there is no need to jumper anything, just disconnect the A1 and A2 terminals on the output of the drive or at the motor. There is very low resistance between each of the pairs due to low armature resistance which may appear to be a short. It sounds like a motor problem you have. Al.

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Reply 4: HCAL, Servo 401 Fanuc 6mb

Andy Fritz replied 1 month, 1 week ago

Originally Posted by Al_The_Man The armature cables are typically in 2 pairs, there is no need to jumper anything, just disconnect the A1 and A2 terminals on the output of the drive or at the motor. There is very low resistance between each ...

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Reply 5: HCAL, Servo 401 Fanuc 6mb

Al_The_Man replied 1 month, 1 week ago

You have to remove the encoder and strip the motor, usually 4 bolts after the brushes are removed. Remove the armature carefully as the magnets are easily chipped or cracked. Al.

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Reply 6: HCAL, Servo 401 Fanuc 6mb

Andy Fritz replied 1 month, 1 week ago

Originally Posted by Al_The_Man You have to remove the encoder and strip the motor, usually 4 bolts after the brushes are removed. Remove the armature carefully as the magnets are easily chipped or cracked. Al....

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Reply 7: HCAL, Servo 401 Fanuc 6mb

Andy Fritz replied 1 month, 1 week ago

Originally Posted by Al_The_Man You have to remove the encoder and strip the motor, usually 4 bolts after the brushes are removed. Remove the armature carefully as the magnets are easily chipped or cracked. Al....

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Reply 8: HCAL, Servo 401 Fanuc 6mb

Al_The_Man replied 1 month, 1 week ago

It depends on how the encoder is coupled, some are more fragile than others, you will have to remove the encoder before the brush assy. Normally the stator comes off easily, you could try a dead blow hammer to tap on the rods to drive the end cap off, it is only the bearing that hold it on, the magnet force also tends to resist the attempts to pull the rotor off. Al.

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Reply 9: HCAL, Servo 401 Fanuc 6mb

Andy Fritz replied 1 month, 1 week ago

Hi Al, If I tap the bolts it would force the whole motor forward toward the ball screw coupling. The only protruding object to tap the brush holder assy backwards would be the cannon connectors or four platic brush holder caps. Oh well I am sure it will work somehow. meanwhile I played a bit more with disconnecting the four armature cables for both X and Y axis. I also jumped pin S23 on both...

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Reply 10: HCAL, Servo 401 Fanuc 6mb

Al_The_Man replied 1 month, 1 week ago

IIRC 410 indicates position error, which you may expect if the motor should be moving. Do you have access to a Insulation Megger? With the motor leads disconnected, you could megger between one lead and ground, if the megger output is adjustable, use the lowest setting, e.g. 500v . Al.

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