Fanuc 6T - 401 SERVO alarm

[Roger Z]

Tsugami Mercury lathe with Fanuc 6T. Got this old beast cheap and repaired the mechanical problems. Am learning Fanuc programming. After several weeks of programming, got the lathe to make parts and was in the middle of editing a line and suddenly got a "401 SERVO" alarm. Found "HCAL" LED illuminated (high current alarm) on the X-axis (left side) velocity control PCB #A20B-0009-0320/07C. After much mechanical checking, found nothing. Swapped the 2 velocity PCBs and the "HCAL" stayed with the PCB. I have been trying to troubleshoot to find the component(s) responsible, but need a schematic to go farther. The ICs Q3, Q4, Q5, Q6 and some of the resistors in that area have fantastically different voltages between the two PCBs. Again, swapped the PCBs and the voltages stay with the PCB. I believe the problem is on the PCB, not in the axis drive. Any ideas? or can anybody supply me a schematic diagram? I tried first with GE Fanuc and had NOOOOO luck. Also had no luck trying to connect the 6T to a PC so I didn't have to stand at the control, but no luck. If this problem can be solved, I will be back to trying to connect to RS-232. Thanks for any help!

[Dan Fritz]

The first thing I would check is the input voltage. Sounds like your 3-phase voltage is too high for your transformer settings.

Look for a big 3-phase transformer in the cabinet (probably below your servos). This transformer can be set with jumpers so that the servos get the right voltage regardless of the shop's line voltage. Instructions for setting these jumpers are in the fanuc Maintenance manual. You should be able to adjust the transformer to accept any line voltage between 190 and 550 vac.

Also, there is a smaller single-phase transformer near the CNCs power supply. There are multiple taps on the input side, and the wire should be attached to the right tap for your line voltage.

This issue comes up whenever a machine is moved. The shop where it was before might have had a different line voltage.

[GPena]

If you swaped the boards and the problem goes with the board (to the Z axis) then the poblem is in the board, getting the diagrams won't be an easy task. As my experience there is a square black box in the board wth a yellow label on the top (1"x1" apro.), this is an opamp from Fanuc, the problem could be there, to isolate the problem you can change that part from one board to the other and test, if you find that this is bad then you can buy it from Fanuc.

Good luck.

Greg.

[Roger Z]

Dan thanks for your quick response!! This lathe was moved from a shop nearby, with the same power. BUT, I would like to check the voltages as you recommend, because the transformer(s) may be set wrong. We have a TOOLING MANUAL, a PROGRAMMING MANUAL and an OPERATOR'S MANUAL, but no MAINTENANCE MANUAL. Where can I get this? Do you know where I can get a schematic diagram for the velocity board? or do you know the real ID number of those ICs that I mentioned? If I can get a data sheet for them, that would also help. I checked all discreet components and found nothing wrong. I expected to find a shorted diode or semiconductor or a bad capacitor, but all looks well. This leaves me with the mysterious "packaged" components.

[Roger Z]

Greg thanks for your reply. I will investigate those black cubes. I really need a roadmap for this circuit board, because it is double sided foil and parts are painted and the whole board is coated with some yellowish film. The foils are almost impossible to follow. I am a skilled electronic technician but am not able to go any farther with my troubleshooting. I need some real service information. Where is it hidden? GE Fanuc doesnt even answer their phone! I was just playing with the phone menu system and waiting an hour listening to music every time I called. I have spent probably 15 hours over a month trying to get a person. It is shameful!

[hiiesalu]

I FIXED MY IKEGAI AX25 FANUC 6T AS SUGGESTED 401 SERVO AND HCAL LED LIT.
1.I SWAPED BOARDS A20B-0009-0320 AND THE PROBLEM FOLLWED THE BOARD, "MAKE SURE"!!! THE PLASTIC JUMPERS LOWER LEFT HAND OF BOARD
ARE SET FOR X AND Z ON MY MACHINE THEY ARE SET DIFFERENT. REMOVE TWO CONNECTORS AND RELEASE TABS THAT HOLD BOARD, BEND TABS JUST ENOUGH TO REALEASE TO FAR AND THEY WILL BREAK.

2. IF PROBLEM FOLLOWS THE BOARD THEN REMOVE BOARDS AND REMOVE 1" SQUARE ISOLATION AMP AT6L-0300-00317 USING A SOLDER SUCKER AND SWAP THESE "BE CARFULL TO REMOVE PART GET ALL THE SOLDER OUT" . IF PROBLEM FOLLOWS THEN REPLACE WITH FANUC PART I PAID $168.00

3. AFTER I REPLACED THE PART AND POWERED UP I WENT TO DIGOS # 800 AND 801 AND ADJUSTED BLUE TRIM POT MARKED "OFFSET" (LOWER LEFT)
AND SET 800 AND 801 TO ZERO BY TURNING KNOB RIGHT OR LEFT

Summary the AT6L-0300-00317 is a common part failure the proudcure too about an hour and save me the cost of a complete board and or service call

[Roger Z]

Thanks for your reply "hiiesalu". I found a used PCB (printed circuit board) for $250 and just swapped it and the lathe is up and running again. I had located the approximate area of problem, and there were four integrated circuits, which had Fanuc part numbers on them. I was not able to get any schematic diagram or any information from GE-Fanuc. There are several money hungry repair services available, but they can go suck someone else's blood. I will NEVER have anything to do with Fanuc in the future, thanks to the way they operate. I still have the bad PCB and will attempt to repair it if I can get some more information. Then I will have a spare. I am wondering where you got the black cube thing from? Did you order from Fanuc or some other place? They told me that they will not sell to me because I am not one of their authorized repair services. This experience opened my eyes to future machine purchases. If I can not get service information with the purchase, I will buy another brand. Thanks to all for your comments!

[hiiesalu]

We have in stock. The price each is $168.00.

Thank you for the inquiry - ordering contact information shown below.

Best regards

Luis M.


GE Fanuc Terms and Conditions of Sale apply to all orders and
quotations.
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USA.
To set-up an account, please request our "new account application" form.
GE Fanuc CNC Customer Care
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CNC / LASER Products Inquiries:
Fax: 1-434-978-5673 Email: service.center@gefanuc.com
Toll Free: 1-800-432-2621
To reach a CNC Customer Service Advocate, select 1
To reach CNC Technical Support and log a new case select 2
Phone menu info:
http://www.gefanuc.com/downloads/cnc..._phone_map.pdf
Visit our Parts On Line Parts Store at:https://esales.gefanuc.com
CNC Parts Information: www.gefanuc.com

[John_B]

Luis M.

I've seen you have offered input on a few issue lately on behalf of Fanuc. Good to see a polite and helpful face to Fanuc as many of us have had less than that shown to us. Hopefully this marks a new direction.
Rgds,
John B

[hiiesalu]

Luis M.

The Fanuc part FIXED MY OLD MACHINE I am glad they still make some of the hard to find parts, for me $168.00 was cheap compared to the service call, new board ect.
Many Thanks to this forum as another member "G PENA" pointed out what part may be bad.

Reguards
ALan Hiiesalu
Defense contractor

[hiiesalu]

Originally Posted by hiiesalu I FIXED MY IKEGAI AX25 FANUC 6T AS SUGGESTED 401 SERVO AND HCAL LED LIT. 1.I SWAPED BOARDS A20B-0009-0320 AND THE PROBLEM FOLLWED THE BOARD, "MAKE SURE"!!! THE PLASTIC JUMPERS LOWER LEFT HAND OF BOARD ARE SET FOR X AND Z ON MY MACHINE THEY ARE SET DIFFERENT. REMOVE TWO CONNECTORS AND RELEASE TABS THAT HOLD BOARD, BEND TABS JUST ENOUGH TO REALEASE TO FAR AND THEY WILL BREAK. 2. IF PROBLEM FOLLOWS THE BOARD THEN REMOVE BOARDS AND REMOVE 1" SQUARE ISOLATION AMP A76L-0300-00317 / T USING A SOLDER SUCKER AND SWAP THESE "BE CARFULL TO REMOVE PART GET ALL THE SOLDER OUT" . IF PROBLEM FOLLOWS THEN REPLACE WITH FANUC PART I PAID $168.00 3. AFTER I REPLACED THE PART AND POWERED UP I WENT TO DIGOS # 800 AND 801 AND ADJUSTED BLUE TRIM POT MARKED "OFFSET" (LOWER LEFT) AND SET 800 AND 801 TO ZERO BY TURNING KNOB RIGHT OR LEFT Summary the A76L-0300-00317 / T is a common part failure the proudcure too about an hour and save me the cost of a complete board and or service call

.

[greenery_fr]

Originally Posted by Roger Z Thanks for your reply "hiiesalu". I found a used PCB (printed circuit board) for $250 and just swapped it and the lathe is up and running again. I had located the approximate area of problem, and there were four integrated circuits, which had Fanuc part numbers on them. I was not able to get any schematic diagram or any information from GE-Fanuc. There are several money hungry repair services available, but they can go suck someone else's blood. I will NEVER have anything to do with Fanuc in the future, thanks to the way they operate. I still have the bad PCB and will attempt to repair it if I can get some more information. Then I will have a spare. I am wondering where you got the black cube thing from? Did you order from Fanuc or some other place? They told me that they will not sell to me because I am not one of their authorized repair services. This experience opened my eyes to future machine purchases. If I can not get service information with the purchase, I will buy another brand. Thanks to all for your comments!

This problem can solve