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Identify smd capacitor

Discussion in 'General Electronics Discussion' started by endruw, Mar 19, 2017.

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  1. endruw

    endruw

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    Mar 19, 2017
    Hello everyone, Can anyone help me to identify this smd capacitor(at least i think it's a capacitor)I attached to this post ,i would like to know what type of capacitor is ,it's value or it's name ,to order it from the web.I'll appreciate any help.
     

    Attached Files:

  2. RodB

    RodB

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    Mar 19, 2017
    Hi - The photo is not real clear but it looks like it may be a diode. The stripe on one end is a clue. The stripe may be the cathode end of a diode or the negative end of an electrolytic capacitor. Electrolytic capacitors are usually larger and a different color. If you have a schematic diagram it would be easier to determine which. Using an ohmmeter may tell you. A capacitor will indicate an open circuit, but since this component is attached to other components it is difficult. Either way, if you can't see any other marks on the component you would be guessing as to the value. Best way is to read the schematic.
     
    davenn likes this.
  3. davenn

    davenn Moderator

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    Sep 5, 2009
    I agree ... looks more like a diode

    type unknown without more info ... circuit schematic etc
     
  4. endruw

    endruw

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    Mar 19, 2017
    Thanks for the replies Rodb and davenn ,i can't find schematic for it ,it's an apple charger for iphone 3 ,i attach one more photo.I think it's a diode too.
     

    Attached Files:

    Last edited by a moderator: Apr 2, 2017
  5. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    Sir endruw. . . . . . .

    Say Whaaaaaaaaat . . . . Do you mean that this is what I would find inside one of those . . . small . . . hardly more than a few cubic inch square SNOW WHITE Apple chargers ; SHOULD a person initially, even be able to NON-DESTRUCTIVELY . . . extract its mini PCB from within?

    If you blow / clean off some of the white faery dust from the board, other markings might further show up, BUT I can now readily see the . . . cramped for space . . . placed aside markings of U2 AND D8 which would definitely make your mystery unit a diode.

    Now . . . U2 we know as a 3 terminal integrated circuit, in this case a TL431, which we recognize as being an ADJUSTABLE “ zener in a chip”.

    NOW . . . . . pull out ye olde DVM and place it in diode test mode function and try its probes across the two terminals of that diode in the charger units, in a no power applied status.

    In the testing it should show up as dead shorted----open circuited---- or its forward junction voltage . . .Vf . . . should read out in one of the two test connection modes (Applied test leads polarity swapped.)

    By virtue of its close circuit proximity to the TL431 . . . I do not tend to suspect a Zener diode.

    Coming back with that good Vf reading should at least confirm if it’s being a conventional diode, with an ~ 600—700 millivolts range OR if it is being down in the 400mv range, you may have a fast switching characteristics unit, OR lastly, a Vf being in the high 100----200’s of mvs, relates to its being a Schottky diode.
    ( Whoooops I guess that I don’t be having too much smarts . . . as spel chex iz dun tellin’ me now, that it shud bees a SCOTTY diode.. . . . . HAH . . . a lot they noes ! )

    At any rate, getting a valid Vf reading should substantiate that it’s basically NOT being a suspect / bad part.

    Matter of fact . . . in referring to my provided schematic of the evolution of those Apple units, we can see the same electronics assigned D8 designator even being used there.

    Even then, it retained the same D8 assigned designation.


    Referring to my provided schematic, YELLOW box, we see Vcc output voltage being basically applied to R13/R28 used as a sampling voltage divider bridge to establish the Zener voltage set up in the TL431.

    AND THEN, we also have a like divider set up at R35/R8 to the right, but with a temp sensitive thermistor R35 in the top leg.

    In temp sensing, the D8 steering / isolation diode then permits the conducting in / insertion of a correcting voltage to override the other settings initial reference voltage.

    TTL431’s drive voltage in the optical isolator to its internal LED modifies the isolated phototransistor for its correction of the other dynamic power supply section of the unit.

    Now, tell us your reading of the Vf spec of your boards D8 diode unit.


    RELEVANT APPLE CHARGER SCHEMA

    upload_2017-5-11_13-8-3.png



    73’s De Edd
     
    Last edited by a moderator: May 11, 2017
    Arouse1973 likes this.
  6. endruw

    endruw

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    Mar 19, 2017
    Wow so much information!So it's a zener diode you think?I can't measure it because the led was broken when i removed it from circuit ,if you can identify it i can easily order from aliexpress or ebay, i must now what it's name ,because it don't have any marking .
     
  7. endruw

    endruw

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    Mar 19, 2017
    I will take photo, form the pcb i have method to extract it from inside without major harm to the case
     
  8. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    I do NOT think that it is a Zener diode.
    If even the tiniest bit of metal is left of the original leads, that would let you touch a test probe tip to them.
    And you can use the sharp corner of a single edged razor blade , or the tip of a # 11 X-Acto knife to dig out plastic to then re-access to an internal lead, having been snapped off.

    Of our universally used / dirt common . . . . and cheeeeeeeap diodes, it is probably right at the specifications of a 1N4148 or 1N914 commonly used diode, but needing infinitely less current pass through, than the mammoth specifications of a 1N4007.


    73's de Edd
     
    Last edited by a moderator: Apr 3, 2017
    davenn likes this.
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    Agree with Edd on that one
     
  10. endruw

    endruw

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    Mar 19, 2017
    Thank you MR. 73's de Edd you helped me a lot ,i looking for a smd diode of the same sepcifications of 1n4148 or 1N914 .
     
  11. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    Sir endruw. . . . . . .

    Oui . . . . . . .exactly

    1N4148 SMD Sub.png

    Once that boo-boo is corrected, then there is the units REAL problem still left.

    73’s De Edd
     
    Last edited: Apr 4, 2017
  12. endruw

    endruw

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    Mar 19, 2017
    I attached photos how did i disassambled the iphone 3 charger,i did'nt harmed it's case i made a very beautiful work .But i can't recognize what the 4 smd resistor's value (i circled it with red) and i replaced the diode (blue circle) but i don't know is it 1N4148 or 1N914. It's not wokring when i plug it to 220v .And thank you for all previous reply. :)
     
  13. endruw

    endruw

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    Mar 19, 2017
    There's the photos
     

    Attached Files:

  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    "Augest". I guess Apple can't spell. Or maybe there's another reason.

    1N914 and 1N4148 are functional equivalent.

    What are the numbers on the resistors?
     
  15. endruw

    endruw

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    Mar 19, 2017
    That's the problem ,i only can recognize one ,because 3-4 parts destroyed in the charger the diode is ovious because it has a tiny hole ont it ,but i don't sure about the resistors 3 of the is left smoke on the inner side of the case ,but i know the resistors can endure lot of heat and maybe they are not damaged only overheated ,or they lose some resistance from they original resistance and i can't read the numbers on them beacuse it's lost it when they overheated.Can you recognize the resistros value from the schematic?
     
  16. endruw

    endruw

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    Mar 19, 2017
    And my second question is it the right diode what i replaced? it's ery similar to the 1N914.
     
  17. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Perhaps you should get a real charger and throw away this fake one.
     
    davenn likes this.
  18. endruw

    endruw

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    Mar 19, 2017
    73's de Edd Do you think it's an 1N914 diode what i replaced?(blue circled on my previous post)
     
  19. endruw

    endruw

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    Mar 19, 2017
    Hello dear members ,can someone help me to identify that 3 resistor what i mentioned in my previous posts?There's a schematic what was uploaded by other member who helped me.I very apperciate any help.
     
  20. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,309
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    Jan 21, 2010
    Unfortunately that schematic fails to list most of the part numbers.
     
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