SMD 5PIN broke - what is it?

Discussion in 'General Electronics Chat' started by Krampi, Mar 12, 2014.

  1. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    Hello together,

    I have a broken hand-held transmitter from RUKU - SF 433-1 Mini/M, 433,920 - of a garage door opener. He is operating with 12V Battery. I tried to build the transmitter in my car and run it with 13.6 volt DC.

    Then the small SMD part broke down.
    Actually i found a lot of voltage regulators in the web, but they all have different pinnings and layouts.
    I took some meassurements on the PCB of the transmitter and painted the wiring of my SMD part.

    Something like a voltage regulator from 12V DC to ?? volt for the separate signal board which produce the 433.920 MHz signal.

    [​IMG]

    Does anyone can give a tip?

    Kind regards,
     
  2. pwdixon

    Member

    Oct 11, 2012
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    It could be a regulator but it could also be something else. Can you read any lettering on the part itself or was there anything on the pcb silk screen?
     
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I guess that is the N71 or M71 that is written on the paper. Couldnt find anything that has five pins though.
     
  4. praondevou

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    Jul 9, 2011
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    If we assume it to be a linear voltage regulator it will be helpful to know its output voltage. What is connected to its output? Some encoder IC maybe? What's the voltage rating of any IC connected to it?
     
  5. absf

    Senior Member

    Dec 29, 2010
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    My record says N71 can be 2N3904 or BFG10X.

    Most probably it is BFG10X from the appearance. See datasheet attached.

    Allen
     
  6. kubeek

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    Sep 20, 2005
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    I don't think that is the one, since the one on the photo still has 4 pins and one missing, so if it was the thick pin that got lost of the BFG10X then there would be only three pins left.
     
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  7. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    The name was like on the picture - X for destroyed letter and then M or N with 71. On the PCB there is nothing to read.
    The output goes to some transistors, resistors, trimmer . No IC logic on the small board. 2 quartzes are also on the board.

    I think its difficult to find out the operating voltage of the " quartz pcb ".

    I attached a picture of it - maybe it helps?
    [​IMG]
     
  8. praondevou

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    Jul 9, 2011
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    I went through nearly all linear voltage regulators on digikey with a SOT23-5 package. there is none with this pinout. All have VIN on pin 1.

    So maybe it's not a voltage regulator but some sort of transistor.

    Can you take a high resolution picture of the PCB?
     
  9. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    Thanks for your ideas, but it has 5 pins - one is missing :-( - and the rest of the 4 you can see on picture.
    But all datasheets of voltage regulators have different pinnings the don´t match - but what it should be instead of?
     
  10. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    High resolution picture will come soon
     
  11. praondevou

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    You can have transistors or Opamps or comparators or diodes in SOT23-5 packages.... Need to do more reverse engineering.

    Is this a single layer or double layer PCB?
     
  12. Krampi

    Thread Starter New Member

    Mar 12, 2014
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  13. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    It is also a part that dont work with 13.6 maybe up to 14.00 volt DC ( from my car ) instead of the 12.2 vold dc of battery. Maybe a hint for the datasheets of the critical input voltage of more then 12.2 volt
    It seems to minimum double - could also be possible to be 3 or 4 layer.
     
  14. praondevou

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    Looks indeed like a voltage regulator, we see input and output ceramic caps.

    I did search for regulators up to 12V...

    Maybe we start with the SIK434, 4-pin component?

    If this is all Asian components it can get difficult though.
     
  15. praondevou

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    They even scratched off what was printed on the other semiconductors. :-(

    Is the circled component burnt too?
     
  16. praondevou

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    What are the physical dimensions of the broken component? Just to make sure it's indeed aSOT23-5 and not something smaller.
     
  17. praondevou

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    Ok, found one from Holtek with the right pinout:
    http://www.holtek.com/pdf/consumer/1015_1v130.pdf

    Not sure if it's this one though. Makes sense because of the 12V max input.

    edit: the marking doesn't match. must be some other Asian manufacturer
     
    Last edited: Mar 12, 2014
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  18. praondevou

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  19. Krampi

    Thread Starter New Member

    Mar 12, 2014
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    Hello praondevou,

    the one you posted looks good. Make sense the n.c. pins just for the better fix to solder with plus and minus.
    I will try to buy one of these HT1015-1 and will report my success.

    The package is SOT 23-5 and the circled one on the picture seems to be not burned. Sensational what you guys all notice :) It has 22.2 KOhm if you measure on PCB.

    Thanks you all for your help.

    Next days im in China - so i can take 2 weeks to post again :)
    Cu
     
  20. pwdixon

    Member

    Oct 11, 2012
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    How do you know what the output voltage should be though? I'm not sure you even know it should be a regulator. Just because the device happens to fit the pads doesn't mean it'll do anything useful.
     
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