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CNC Board Repair and Eeproms

Discussion in 'Repairing Electronics' started by JonesPrecision, Feb 17, 2016.

  1. JonesPrecision

    JonesPrecision New Member

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    Hello,

    First post here. I hope I have to come to the right place. I've been playing with electronics all my life and am now finally reading more about them and learning the theory behind circuit design. A project has come up recently that I wanted to do a little research on before I start. I recently acquired a Hardinge CNC lathe and it is throwing an error. The error relates to the main control board and two eeprom modules that store the ladder diagrams for the machine. This machine was built in 1988.

    I have some standard test equipment and will likely be purchasing a scope in the immediate future. I am able to test circuits for simple things but I have no idea about eeprom chips. The problem either points to 2 bad eeprom chips (which seems unlikely that they both went at the same time), a dead battery that saved the memory (hopefully) or part of the main control board being the problem. I don't have power to the machine quite yet but when I do I will start with the batteries and work up from there.

    My two biggest questions are is there a way to test the chips without erasing whats on them and is there a way to see if the board is effectively communicating with the chips? A repair of this magnitude is going to cost be about $1500 and a board replacement is somewhere in the neighborhood of $5k so I would like to troubleshoot it myself initially.

    The data that is stored on the chips is absolutely vital to the way machine runs. Losing that data means I need to pay to have it repaired or scrap the machine. I would like ot be able to back that data up in the future if feasible at some point so I can make copies but that would be after I get it working again.

    Any help is appreciated.
     
  2. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Are there any numbers on the EEPROMs? Can you post some pictures? From that era, they are more likely to be UVEEPOMS - UV erasable and they will have a window on the chip if they are. The battery is almost certain to be dead and need replacing, I would do this first.

    Mike.
     
  3. JonesPrecision

    JonesPrecision New Member

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    They don't have a battery directly on the chip. Actually after looking at the pics there is a label on them so maybe its under that. Maybe a small round one in the middle?

    The battery I was referring to was for the whole machine and if that goes dead you lose all parameters and have to reenter them. The machine backup battery doesn't seem dead but I know this error can be related to them going dead.

    I know they are Toshiba TC57256AD-15. They are labelled E-1 and E-2 on the stickers.
    [​IMG]
     
  4. dave

    Dave New Member

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  5. JonesPrecision

    JonesPrecision New Member

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    The battery backup is comprised of 3 D cells and currently reads 4.78 volts. I know that's probably getting low. The previous owner said he changed them not too long ago but who knows. They dates on them are good well past 2020. Not sure what new ones read nowadays but its recommended you change them once a year.
     
  6. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    It looks like a Fanuc control, Normally the ladder eproms are OK if the battery goes, just the parameters require reloading also including the 900 or 9000 option parameters depending on model.
    What makes you think it is in the ladder?
    The battery is always changed with the power on.
    Max.
     
  7. JonesPrecision

    JonesPrecision New Member

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    Max-good eye! Yes it's a Fanuc OT-B control. The error is a 998 Rom Parrity Error which relates to the main board and the message on screen references both E01 and E02. It can refer to either but on mine is shows both. From the solutions I've found it can be the battery, the eeproms themselves or the whole board. You're correct about changing it when it's on but since I can't power the machine up with this error there is no way of safely changing them. I have to reset/clear everything to get rid of the error anyway (only way) so my parameters are gone regardless.

    I don't think its the ladder I'm just worried if its a chip I'm going to lose the ladder info on it. Like I said though I don't know a whole lot other than what I've read so far from people with similar problems. Since the machine is so old there's a least a decent amount of info there. Right now I'm just trying to do my homework om what is possible with the chips in their current state and if it them or related to them what I can do prior to possibly fixing this error.
     
  8. Pommie

    Pommie Well-Known Member Most Helpful Member

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    I doubt very much if it's the EEPROMS as they are UV erasable ones and have a sticker covering the erase window. Why can't you power it up?

    Mike.
     
  9. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Not much to go on, but the programmable ROMS could have gone south. OK, both at the same time is a little unusual.
    they can go bad.

    Your pic didn't show up. Would like to see a pic of the board.

    Was this machine transported or moved?

    Making sure the chips are seated. Initially push on them.

    You can reseat some of the IC's. I would suggest a puller. If you don;t use one, the pins bend and eventually break.

    The GQ-4x http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp is a reasonably priced programmer that supports the chip. Many programmers used the parallel port only and emulation WON'T work. This one does not.

    parity generally means even or odd. Even means there is an even amount of 1's and odd mean there is an ODD amount of 1's. I don;t know if any other data like an address is also printed.

    A parity error on the surface doesn't mean much to me. A checksum, would be more appropriate. Checksums are created by XORing all of the bits or some other algorithm. It generally checks the entire program for single bit errors.

    ==

    In general when troubleshooting ANYTHING, one needs to measure the power supplies and the ripple on the power supplies. Doing tis follows the inspection phase.
     
  10. Les Jones

    Les Jones Well-Known Member

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    I think that getting the data to program the ROMs will be more of a problem than actually programming them. I think the manufacturer may sell the ROMs programmed but I doubt that they will provide the data to program then yourself. You may have to buy a second hand board and hope the ROMs are OK.

    Les.
     
  11. granddad

    granddad Active Member

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    Hi JP
    This would suggest to me the ROM data has degraded sufficiently to cause a sum check failure, finding a UVEROM chip should not be difficult, cloning the data more so , needs a reader / writer... and a DOS PC , ( adjusting voltage Vcc or temperature may help reading ) Strictly speaking the labels should have a black coating chip side, white paper does not stop UV... I had it happen on a printer where the ROM chips got a little sunlight through a grill every time cover as opened to change paper .... couple of years ...error.
    Could it be the '9020' chip that certainly looks like a windowed device , ( Non windowed chips can still be UVEROM ..OTP one time programmed and could be replaced by windowed )
    Edit
    Think you can still get ART programmers ( had one century's ago !.)
     
    Last edited: Feb 18, 2016
  12. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Totally agree with the paper not blocking UV sufficiently over time. The labels I used were a grey color and somewhat metalic.
     
  13. JonesPrecision

    JonesPrecision New Member

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    The board is kept in a sealed box. It shouldn't have been open much if at all and even so it's way back in a corner. The amount of light that actually able to reach back there is very little. I guess anything is possible though.

    The machine was moved but this was a known issue when buying the machine. I got it for practically nothing. I don't have power to it yet because I'm building a phase converter.

    Here's is the datasheet:
    http://www.datasheetlib.com/datasheet/733782/tc57256ad-15_toshiba-semiconductor.html#datasheet

    [​IMG]
     
  14. JonesPrecision

    JonesPrecision New Member

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    Here is another pic if the first one didn't go through.

    [​IMG]
     
  15. granddad

    granddad Active Member

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    JP When you do get it powered I would check all the voltage levels, low +5 Vcc ( yep I know you were ) could make a difference with logic levels on old UVEPROM chips. You could try warming the board up slightly around the ROM area. I see test points next to ROMS
    edit
    Had a thought,, sometimes socketed chips can ease themselves out of the socket , also pins may become tarnished due to some sweaty operator inserting them...
     
    Last edited: Feb 18, 2016
  16. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    The other problem is the ladder is written by the MTB not the system manuf (Fanuc) as it is unique to that version of machine and traditionally a very expensive software and programming unit was used to program.
    There are also main system eproms that Can be obtained from Fanuc, usually.
    Do you have all the manuals? Unfortunately I only have the 0C & 0D in PDF.
    Max.
     
  17. granddad

    granddad Active Member

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    That would seem to suggest a E1 & E2 ROM addressing or data bus issue ...
     
  18. JonesPrecision

    JonesPrecision New Member

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    Is there a way to test for this?
     
  19. JonesPrecision

    JonesPrecision New Member

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    I do have all the manuals including some good ones from Fanuc. I'm pretty sure I also have a ladder printout but I hope I never have to use it. I would assume a good repair shop would have these files if I had to send it in. I've also been in touch with an applications engineer from the MTB who might be able to get me what I needed.
     
  20. JonesPrecision

    JonesPrecision New Member

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    I've seen repeating them mentioned before so that's good to here it's a possibility again. I may try that.

    As far as the testing for the 5v vcc is that something that is constant or only during communication?
     
  21. JonesPrecision

    JonesPrecision New Member

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    KISS-

    Regarding checking the power and ripple would this be a good reason to pick up a scope? I've been wanting one and will probably get one anyway but if something were to push me over the edge I'm ok with that haha.
     

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