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ID black SMD

Discussion in 'General Electronics Chat' started by The Bishop, Jun 13, 2018.

  1. The Bishop

    The Bishop New Member

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    What is the black smd device on a circuit board with 000 on the top?

    Can they pop off in lightning comes in on a dvr card?

    All I have is the two empty solder points left on two dvr cards.
     

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  2. Pommie

    Pommie Well-Known Member Most Helpful Member

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    I would guess that L5 is an inductor. Can you unsolder a good one and measure it or read the numbers on a good device?

    Mike.
     
  3. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Here is the picture of L5. Note the lack of solder on the right side. Maybe it was not soldered down right.
    [​IMG]
     
  4. dave miyares

    Dave New Member

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  5. unclejed613

    unclejed613 Well-Known Member

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    L5 with 000 on it was a 0 ohm resistor, also known as a jumper.
     
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  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    I suppose the L5 could stand for Link5. Is this normal?

    Mike.
     
  7. JonSea

    JonSea Well-Known Member

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    The component at L5 in the first picture is not the same as the 000 component at L5 in the second picture. In the first picture, "L5" has thickness; it's not thin like a resistor or 0 ohm jumper.
     
  8. dave miyares

    Dave New Member

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  9. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    If lightning made them 'pop off' there would be a LOT of visible damage, and 'blast marks' where the resistors were. The unit would also be toast!.

    If the components aren't there, they were either never fitted (often boards are designed for various uses, and unused components aren't fitted in specific versions), or someone has removed them.
     
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  10. Mickster

    Mickster Well-Known Member

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    In Ron's enlarged picture (Post #3) of that section of the PCB, IMO, rather than there being no solder on the L5 RH pad, it appears to be over-exposed and the same result can be seen at C26 + the resistor above.
    Unless there is evidence of a component being there previously, such as remnants or an impression in the remaining solder, pads with a smooth blob of solder were more likely to have never been populated.
     
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  11. The Bishop

    The Bishop New Member

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    All three shots are three different dvr cards. the pic with both L5 and C28 devices in place are on a totally bad card.

    The second pic is a dvr card with camera port 1 open now. The last pic is another dvr card with camera 4 port open now.

    All three cards went bad after bad storms came through the area.

    The two card with missing a smd still work but only has 3 good camera ports now.

    I'm learning and looking for amswers.
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Nothing to do with missing components I'm afraid.

    If lightning damage isn't blindingly obvious, it's almost certainly semiconductors that have failed - and often multiple ones.
     
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  13. The Bishop

    The Bishop New Member

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    I checked the 10 other dvr cards that failed at one time or another over the years. I keep damaged cards to part them out if I need something. Every card has a smd at L5 and C28 so it must be important to have them in place.
    I'm going to swap a couple of smd to replace the two that disappeared during a storm.
     
  14. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Feel free, but components don't just disappear during a storm - and if they had, the reason would be blindingly obvious with the board a smoking and burnt ruin. It's much more likely that those parts are only fitted in certain revisions.

    I've repaired (well, tried to repair) many lightning damaged items over the decades, and provided insurance estimates for the damage - almost always write-offs.

    I have repaired a few lightning damaged TV's, more for my own interest than anything else, but it's a long and expensive job:

    Code (text):


    while (tv not working)
    {
        fault find();
        replace duff IC();
    }

     
    Bit of C type code to explain the technique :D
     
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  15. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    L5 was most likely originally intended to be a ferrite chip, its purpose to suppress noise coming in on the trace. They are effectively inductors, hence the "L" designator prefix. Sometimes after design and testing they are deemed unnecessary and are replaced with 0 ohm (jumper) resistors during assembly. I am willing to bet that is exactly what happened in this particular case. You can probably replace it with another 0 ohm resistor and not have a problem.
     
  16. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You're rather assuming it's supposed to be there? - do you think the 'surface-mount fairies' came round and stole it :D
     
  17. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    I admit I only skimmed the first post. I thought he said one was damaged and was looking for a replacement, but similar boards he had weren't populated the same.

    If the solder is smooth on the pads, then the component was most likely never installed. Leave it unpopulated.
     
  18. The Bishop

    The Bishop New Member

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    That brings me back to my other post, The other 10 identical vdr cards have both L5 and C28 connected with a smd so I thought these two dvr cards, which they are all identical cards, the smds are missing.

    All the other identical cards are bad due to storm power surge have L5 and C28 populated. These two have missing parts compared to the other 10.
    All the other cards failed to work at all. The two cards with missing parts in question do work. The problem with each card is now they each have a camera port open. One card has camera port 1 open the other card has camera port 4 open.
    When I replace the smd in a few days I'll know if anything is different.
     
  19. The Bishop

    The Bishop New Member

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    Good News!

    I changed the L5 SMD today and the DVR card works again.

    I pulled a similar smd off another bad card and put in L5.

    I guess that means it must have popped off during a storm. The L5 location in Pic #10 shows solder only on one spot. The other spot looks pristine as if it never had a smd there. I had no other option but to try.

    Now I'm looking at the C28 smd.
     

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