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  1. #21
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    Sounds promising!!

  2. #22
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    Here is the picture of the cracked track, is this repairable?. Definitely seems to be the culprit as it is on the correct chip and even leading to the correct area of the chip that has popped both times.

  3. #23
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    Definitely repairable! I'd suggest you cut out that offending length of burnt track so it's not flapping around in the breeze, and then re-make the connection with a short length of thin solid core insulated wire. You're lucky in that it essentially connects two of the chip pins together, so you can use the PCB pads for those pins as end points on which to solder your little wire. Pull the chip out and d the work. Given a few minutes with the chip datasheet we could also work out which pin has become disconnected, and hence what the possible issue might be.

    Now of course it could be that the track got burned out as the chip failed, and hence wasn't the cause of the failure - but more the result. Or indeed, has the chip actually failed? Could the board have failed whilst the chip is still OK? Looks like that track took a bit of an overload, but why is that?

    Datasheet, datasheet....

  4. #24
    Thanks Graeme, i will see if i can find the data sheet online.

    I would say both chips have definately failed, the black plastic has popped in both cases and in the case of this particular chip i opened up the contol box fairly quickly and the place where it had popped was still melted and gooey. But like you say whether this failure resulted in blowing the track or wwhether the track blew as a result is a different matter. I will admit i was not particularly thorough last time i replaced the chip in checking the back of the pcb, i just tested the socket pins were gripping ok and only quickly scanned the back so it is possible that this crack was there prior to replacing the chip.

    This failure did take out an 8 amp slow blow fuse on the power supply too
    Last edited by howser37; 02-02-2017 at 04:28 PM.

  5. #25
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    OK, so a quick look at the datasheet suggests that the "disconnected" pin is pin 15, and that it is normally connected to pin 24. This makes sense and these are the two main voltage supply inputs for the motor drive stages. Hence if one of the motor windings was taking too much current, that thin track could fail. Looks a bit thin to me for a motor supply line? Designed to take an amp or two? Hence maybe it simply burned out and effectively disconnected the motor? Worth a repair and a retest?

  6. #26
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    OK, just seen your latest email - scrub the retest! New chip required, but the question is - why did it fail? The motor must be taking too much current at some stage thus blowing the chip and in this case taking the voltage rail track out too, a bit like a fuse. I suspect it must have been intact last time or your repair would not have worked. Hence I think this is a symptom of the latest failure rather than its cause.

    I think I'd be checking my motor wiring for issues, because if there is a problem there, you'd potentially end up blowing whatever you connect - new drivers for example - until that is fixed!

  7. #27
    Thanks Graeme, i will find a magnifying glass and attempt the repair this evening and will test it tomorrow and see what happens, if it blows up it just means i get my new control box more urgently lol

    I will also take a look at the motor wiring too

    Although the track is clearly damaged and fractured it was making contact when i was looking at it, so is it possible that if it was still making some kind of contact that it would have worked with the new chip for a short period of time?
    Last edited by howser37; 02-02-2017 at 04:39 PM.

  8. #28
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    You'll still need a new chip though? Or can you steal one from the unused 4th axis driver?

    Either way, definitely check the motor wiring for shorts first!!

  9. #29
    I assume i can steal the chip from the 4th axis without it causing a problem being absent. I also have a new one on the way that i ordered last night online
    Last edited by howser37; 02-02-2017 at 04:41 PM.

  10. #30
    GND's Avatar
    Lives in Cambridge, United Kingdom. Last Activity: 3 Weeks Ago Has been a member for 2-3 years. Has a total post count of 60. Received thanks 2 times, giving thanks to others 11 times.
    I'd say removing a driver should be fine - nothing connected to its outputs anyway, so a useful source for another chip.

    But I will emphasise again - there must be something causing these to draw too much current, so without finding the root cause, it will likely just keep happening....

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