DM8000 - can't flash - too much data (or bad sectors)

Discussion in 'Hardware troubles and Repair support.' started by jumperger, May 5, 2019.

  1. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Just add the black probe to a ground spot, for example the network or other metal on the board, and with the red probe to the measurement spot.
    Of course, do not power on the board while doing a ohm measurement, and yes, these values where measured while the nand chip has mounted.

    Tip, add a needle to your red probe to measure smd parts.
     
  2. jumperger

    jumperger Member

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    I'm used the golden Ring around one of the fixing screws n the motherboard , is that OK?
    With that it seems that all I/O have 2.44k and one has 2.45k, but I'm not sure.
    Tomorrow morning I will go to see a friend at his workpace , he has sort of magnifing glass where you put you head onto, like the submarines do when they look into the periscope.
    In my measurements it seems like Vcc and the unused pins aside have all 3 a 44,5 value. Let's see what tomorrow brings. Perhaps I have some shorts behind the pins.
     
  3. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Short circuits, and then probably between the side by side pins, are simple to check by measuring the pins to each other.
    With a nand flash chip, there is no pin that is linked to a neighbor pin.
    You will always have to measure an ohm value or no ohm value on two pins next to each other.
    The use of needles on the probes is also useful for this measurement.

    If you mean that you use one of the screw holes as a ground location, that is of course also good.

    As for the nand flash chip pins contact to the motherboard measurements it's better to measure them on the legs of the nand flash chip, and compairing it to the value of the motherboard.
    Only then you known for sure that all the pins which are used are good connected to the board.
    In any case, since you have some access to the nand flash chip, it seems to me logic that it must be related to the I/O pins.
    Be sure that all these eight pins makes a good contact to the board, as also not one has a short circuit to a pin next to it.
     
  4. jumperger

    jumperger Member

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    It seems that there are no shorts.
    Here are the Ohm measurments:
    I/O side: pin 25 - 48
    all I/O pins 2.43 - 2.45 kOhm - Vss 0 Ohm - Vcc 45 Ohm

    other side: pin 01 - 24
    WP 2.45 kOhm
    We 7.57 MOhm
    Ale 7.62 MOhm
    Cle 7.48 MOhm
    Vss 0 Ohm
    Vcc 45 Ohm
    Ce 7.26 MOhm
    Re 7.26 MOhm
    R/B 1046 Ohm

    As you may notice the kOhm and MOhm values are half the size then yours.

    But I noticed a difference in your board and my board, at mine there is a bridge between pin 37 Vcc and 39 NC see the picture on page 3 near the C902.

    Could yu check this on your working mainboard as it has nearly the same production date then mine.
     
  5. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Question, bridge between pin 37 Vcc and 39 NC
    Not sure what you mean but a bridge between the 3.3v and a NC pin seems to me not good.
     
  6. jumperger

    jumperger Member

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    F103EA8E-563D-4B23-B9B2-930338FD189B.jpeg here a detail from my picture on page 3:
     
  7. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Ah okay, I will take a closer look today, when I'm in my work shop.
     
  8. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Sorry to say, but today I was not be able to get to my work shop, therefore I had not the possibility to measure these pins.
    Most likely it will be Friday in the evening, but since it looks as if it's a print track, then it seems to me an normal connection, but based on the datasheet it should be a not connected pin and thus to me it seems not a issue when it's connected.
     
  9. jumperger

    jumperger Member

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    No problem for the delay , I thank you so much for your help.
    Without knowing that I could find advices with you, the box would already have bin recycled.

    Thanks.

    Pin 39 does not have a short with 38 , only with 37 and thats normal as there is a printed linewhich connects them. I mentioned this to show you that your empty board with the Ohm measurement has a different layout then my mainboard. And I thought as the production date of your working mainboard is nearly the same as mine, maybe both have the same layout and you could check if this layout hast different Ohm values the your empty board and the same as my board?

    Have a nice evening and perhaps the oranje will make it to the final ;-)
     
  10. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    I have measured on three motherboards and non of them has this connection pin 37 and 39 thus I have no clue why you have this, or it had before another brand/type nand flash chip, or it's done to feed some other circuit.
    In any case, since this pin 39 is not connected internal in the nand chip, it seems to me that it can not do any harm.
    But by doubts you could consider to lift up this pin to isolate it from the circuit.

    As for the to low Mb's it gives, The only thing I can think of is a bad connection of one of the I/O pins, or the nand flash chip has been damaged somehow.
    However, based on your measurements, it looks to me that it just should work.
     
  11. jumperger

    jumperger Member

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    Thanks for checking this.
    For the Ohm measurements, are they related to the chip? I thought they would measure the resistance on the board?
    I put this chip in: MT29F2G08AADWP-ET-D-
    and originaly it was MT29F2G08AADWP---D I think the ET stands for Extended Temperature (-40° till +85°)

    Last step to check would be 3,3V measurement on the NAND chip, but this seems very difficult to me.
     
  12. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    To me it seems that it does have the 3.3v, otherwise you had no readings of the chip.

    The Ohms reading values are a total value measured between the ground and the measured pins.
    The best ground spot (I think) is to take it from the network connector metal case, or the metal from another connector as the lnb connectors.
    And these are the total ohm values which were given from the nand flash chip, and the cpu when they are I/O pins.
    In any case, the value of the nand flash chip pin, and the motherboard solder pin must give a same value, otherwise does the nand flash chip pin not making a good contact.
    The values from the I/O pins does not have to be the same as mine, because of the age of the Cpu, and nand chip it may be different.
    But a good indication is that when all the I/O pins from the nand flash chip which are soldered to the motherboard are in a same ohm range (it may slightly different between them), then you may assume that all these pins are correctly connected, as also that the cpu prints tracks to/from it are fine.
    You say that you measured them and all I/O pins are between the 2.43 - 2.45 k Ohm, when this are measurements from the nand flash chip pins, then you may assume that all is correct, and all well soldered.

    As for the ohm measurements, they are save to execute, because the board may not be powered up.
    I always measure my motherboard by ohm when they were not powered up for a while, let say at least something as 5 minutes, otherwise the ohm values may differ when the board or some circuits not has been fully unloaded, or the cpu is still warm, which also may give another value then when it's cold.

    Ans as for the ET question, yes indeed, as far as I also see it, It's the markings code for the OTR.
    Snap1.jpg
     
  13. jumperger

    jumperger Member

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    Do you have a last idea what I could check to find the fault on the board?
     
  14. Johnny B.

    Johnny B. Technical Support Staff Member Moderator

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    Yeah difficult, but when you have checked all the used nand flash chip connections and it still gives a to low size.
    Then it must be a issue with the nand flash chip, or some connection to it.
    What I would do is removing the chip, and checking it with my nand flash chip reader to see if it's still works.
    And also check the motherboards connections when it removed.
    But I assume that you not have a nand flash chip programmer as the xgecu tl866ii plus or a better choose, the tl86-plus.

    I am also willing to send you a used but tested nand chip, contact me via Pm if you want.
    But still, the most important thing is to know if there are any problems with the nand flash chip motherboard connections to / from the cpu before you start installing another chip.
     
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