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IndustryArena Forum > Machine Controllers Software and Solutions > Fanuc > Fanuc 3m encoder disconnected error
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  1. #1

    Question Fanuc 3m encoder disconnected error

    I recently bought a Yuasa Enshu Accu-mill with a Fanuc 3m controller. When I fired it up the first time, I got a servo error 34 (z axis). Looked in the manual and found it meant the encoder cable was not connected. After checking it thoroughly, I tried several more times shutting it down and restarting. Eventually, it came up and worked fine. After a day or two, it did it again, so I took the cable loose at the motor, cleaned it thoroughly, reassembled, and it worked again. Now its down again, can't make it come back. According to the manual, the only three things that could be wrong are bad motor, bad connection, and bad master PCB. I checked all the connections again, but no help. I swapped the y and z encoder cables where they come into the controller and attach to a large PCB on the door, but the error stayed with the z axis. It should have gone to the y axis if the motor or connections were bad. I swapped them back, and swapped the cables from that board to the y and z driver boards, error still stayed on the z axis, so I swapped them back. I swapped the driver boards themselves, thinking one of them may be bad, but it STILL stayed on the Z axis. I'm almost at a loss here, any suggestions?
    Thanks
    Nate

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Today I had an identical fault on a customers Mazak T1, If you swap the encoder and cables where they go into the main PCB and it stays on the same axis , then it points to the encoder input IC's on the MB.
    It might check to see what common ic's are first inline from the connectors and replace them, or the PCB.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  3. #3

    Main PCB

    I'm pretty new to this sort of thing, and pages are missing from some of my manuals, so bear with me. The Main PCB would be the one in the door (probably different for each machine) that the encoder cables hook to initially? In about the middle of it, there's a red LED, but it doesn't light, and right above the 4th or 5th cable connection, there are 3 pieces about 1" square, and th middle one has one edge broken or burned , but not really so much you can see its innards. If I have to replace this board, where would I find one, and how much should it cost?

    Thanks
    Nate

  4. #4
    Community Moderator Al_The_Man's Avatar
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    Fanuc USA, Ebay or Google for repair/suppliers of Fanuc parts.
    If you get a used board, you may have to swap the eproms (memory IC.s) from one to the other.
    Also you will need to record all the parameters for reloading, unless you have bubble memory.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  5. #5
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    We can test and repair that board if it needs it.
    Call 813-983-1870
    CNC Diagnostic LLC

  6. #6
    Just got this board back from Tennessee Industrial Electronics, they rebuilt and tested the board for me. The board had some visible damage that obviously had to be fixed, which is a good thing, because I get the exact same errors as I did before I sent it. Servo Error 34 (z axis encoder disconnected) I can unplug all 3 encoder cables and get errors on all 3 axes. Then I plug the z cable into x or y socket and that error goes away. Plug any of the cables into the z socket, and it stays. Any suggestions? This was sold to me as a functional machine, but now almost 5 months later I still haven't cut a single chip.
    Thanks in advance
    Nate

  7. #7
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    When you swap feedback cables you also need to swap command cables.
    On your master board M6 is the command cable for X and M7 is the feedback cable for X axis. M8 command M9 Feedback Y axis. M10 command M11 feedback Z axis. These cables should be swapped in pairs.
    Im surprised that since you paid TIE for the repair they could not provide you with any support.

  8. #8
    Community Moderator Al_The_Man's Avatar
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    It sound to me like you still have a problem on the board on the Z axis input, it appears you have proven out the Z axis motor and cables.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  9. #9
    I just talked to TIE again and they confirmed the problem is still in the PCB. They said the error showed up intermittently when testing/fixing and after a week of testing without it showing up again they assumed it was fixed. Back to Fedex I guess. Thanks for the input!

  10. #10
    Mainboard is back and completely functional!!! Thanks again to everyone for your input. Now I'd like to know a little about communicating with the Fanuc M3 control. The old tape reader is still present, but I have no intentions of using it. There is an RS-232 port where it plugged in, and I'd like to know how to hook up a PC to the controll and make the two of them talk to each other. I don't know a lot about this, but I think I understand that pin 25 on a Fanuc RS232 is 24 Volts and my PC probably wouldn't take that very well, am I right? I've seen behind the tape readers and read some posts about replacing certain chips on the mainboard to increase the length of a program that the control can recieve, are these really necessary? My end goal is to drip feed with unlimited program size. Is the chip replacement only if I want to transfer an entire program, or is it needed for drip feeding too? Is the BTR necessary, or can a PC communicate directly with the control. The reason for this, I run some programs that are really more of 3d carving than machining and some reach several Megabytes.
    Thanks in advance!
    Nate

  11. #11
    Community Moderator Al_The_Man's Avatar
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    I think you will find that what looks like a RS232 port is the punch output.
    You may need a BTR, you can get them with memory storage so that it will act as drip feed.
    I just installed a Cimnet BTR on a Cincinnati 900.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  12. #12
    I found a diagram in the electric circuit diagram manual. (I'm glad that came with it, even if this info doesn't help) The connector labeled RS-232 into the control (not the cable from the reader) has the following pinout:
    1-FG (GROUND)
    2-SD
    3-RD
    4-RS
    5-CS
    6-DR
    7-SG
    8-CD
    14-TTY3
    16-TTY2
    17-TTY1
    20-ER
    25-+24v

    The cable from the reader itself is as follows:
    1-FG
    2-SD
    3-RD
    6-DR
    7-SG
    11-RDY
    U10-200A
    V10-200B
    G-G
    I don't have a clue what the last three are, but they're in the same diagram. There's also some info on connecting an ASR33 teletype but I didn't think that would be relative. Am I wrong in thinking this is a standard RS232 connection that should plug straight into a PC if I cut out the +24V wire? What could happen if I tried it?
    Thanks
    Nate

  13. #13
    Community Moderator Al_The_Man's Avatar
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    It certainly looks like RS232, you could try hooking a serial port up and try it, you may have to experiment with the protocol, baud rate etc.
    Do you have the parameter list?
    I show some for setting the RS232, e.g. 0014 bit#2 for 20ma or RS232
    0068 & 0069 baud rate
    0013 #0 is stop bits
    Parameters 0005 & 0068 when setting parameter is 0
    parameters 0014 & 0069 when setting is 1
    The setting parameter is in parameter 0000 but they do not mention what bit,
    I believe on the 3, the 0000 parameter is options?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

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

  14. #14
    Parameters look the same. 0000 is setting parameter, but I don't know what that means. 0014 sets 20A/RS232. 0068 sets Baud rate. I have a complete parameter list. If I get them set the same, how do I initiate the communication, softwarewise? I think I can figure out the PC end, but how do I set the control to send/recieve, and what would be the procedure for drip feeding? I think I'll give it a try tomorrow, let me know if there may be some looming disaster I haven't considered.

    Thanks!
    Nate

  15. #15
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    Quote Originally Posted by nathanclymer View Post
    Parameters look the same. 0000 is setting parameter, but I don't know what that means. 0014 sets 20A/RS232. 0068 sets Baud rate. I have a complete parameter list. If I get them set the same, how do I initiate the communication, softwarewise? I think I can figure out the PC end, but how do I set the control to send/recieve, and what would be the procedure for drip feeding? I think I'll give it a try tomorrow, let me know if there may be some looming disaster I haven't considered.

    Thanks!
    Nate
    Was there a positive answer of what was causing this z encoder cable error. I have the same board with the same problem and I need to get it fixed.

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