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Can someone help me ID 2 components pleased?

Discussion in 'Datasheets, Manuals and Component Identification' started by kevinm34232, Oct 19, 2017.

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  1. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    L1 and D1 burned up, L1 marking is 102, I'm guessing 1000uH but I don't know what replacement I can use.

    Diode marking is
    A4
    VD05

    Thanks for any info!
     

    Attached Files:

  2. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    That inductor looks like a common mode choke (4 terminal) rather than a simple inductor (2 terminal) or perhaps an impedance matching transformer.

    It won't be easy to identify or replace unless you have access to the schematic.

    What make/model of equipment is it? Is the connector beside it the power input?

    On the basis of it being a power socket then the inductor 'could' be bypassed and the diode is potentially a reverse polarity protection device that can be replaced by many simple 50-to-200V 1A diode.
     
  3. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    Yes it is the first 2 components after the power connector. This part is from a water softner controller/timer. Manufacturer is Pentair Model 740. Nothing on the board or device but the stickers
     

    Attached Files:

  4. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    Can I see a close up of the 8-pin device labelled VR1? It looks as if there may be some damage there......

    Either way, in the latest picture, there are two tracks going 'vertically' from the power socket to L1. These go 'in' on one side of L1 and exit directly opposite so you could remove L1 completely and just short out 'in' and 'out'.

    The diode has probably gone short circuit so needs replacing - as stated practically and 1A diode would work, even a wire-ended version.

    But VR1 may be the 'killer' here. If it is damaged then the reverse polarity event may have gone further than the diode/L1 and destroyed the board.
     
  5. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017

    Attached Files:

    Last edited: Oct 20, 2017
  6. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    No, that looks ok.....

    I've searched Digikey and Mouser for your inductor but not found a matching one. You can try yourself using 'SMD common mode filter' as the search word.

    As mentioned, the filter is potentially redundant (fitted to meet EMC standards but unlikely to cause any issues if you link it out).

    The diode could be something like this:

    https://www.mouser.co.uk/ProductDet...Q8nqTKtFS/BUuz6Zx2fl0pbz26EUz6WddcIZLyzgRBg==
     
  7. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    Thank you so much I will report back! Does the 102 marking determine anything?
     
  8. kellys_eye

    kellys_eye

    4,275
    1,147
    Jun 25, 2010
    Potentially the inductance - not sure whether it's 100μH (most likely) or 1000μH (not big enough). Either way you would need to find something to match the footprint so browse the search results and compare....
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,839
    Jan 21, 2010
    It's not impossible for that to be a 1000uH common mode inductor. Given that the core only sees the difference in currents, it does not have to be large. The main issue is the number of turns you can fit of a gauge wire that can handle the current.

    However I would agree that replacing it with a couple of links would be a viable option, if only for testing.

    Edit: I have some 1000uH inductors in a 1206 package (or a package not much larger), so size isn't everything.
     
  10. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    Identifying the blown parts is one task of the repair job.
    Finding out why they are blown is the other.

    Note that diodes D1 and D3 are the same,probably series blocking diodes.
    By measuring D3 you can find out if it is a Si-rectifier or Schottky diode.

    The LM317L output voltage at pin2 (about 3.3V?) is set by R4 and R5 ,can you tell there values?

    Please check the connection of the cathode of D1, is it connected to VR1 pin1?
    There is another connection on the way (yellow-most probably a capacitor),what is it on the other side of the PCB?
    To what is it's other leg connected,GND?

    Please check the connection of the Anode of D1 to where is it connected to L1-L1A,GND?

    What is the input voltage at the input connector,value and type(AC,DC)?

    water_circuit.jpg
     
    Last edited by a moderator: Oct 20, 2017
  11. 73's de Edd

    73's de Edd

    3,138
    1,320
    Aug 21, 2015
    Sir Kevin . . . . . . .m34232?

    Isn't that connector being where your units wall wart plugs into and then the power input initially routes down
    to TP's 1 and 2, where they then encounter THE referenced EMI / RFI ( "CRAP" ) filter ?
    And then, if its two coils are intact, the power can then contnue on down the boards foil paths .

    See if the connection nearest to D1 diode ohms out as being connected to the outer shell of the mentioned
    connector.
    Then check to see if continuity is being made between the central pin of the connector and the other
    connection that is being the furtherest from D1 for referencing.
    If not, go back and see if both of the connections even make it to the initial TP1 and 2 connections.
    Then you note that circuit foil makes a right angle turn and heads for the side of the PCB and
    travels parallel to it for a distance.
    Keep going down until you see yellow buttoned SW5 , just on past i,t you will see TP4 markup and some vias connecting thru to the other side of the PCB.
    See if you have a copper foil exposed / burnout in that area.
    Possibly linking to leaded resistor R18.

    The units GREEN ON GREEN foil to board differentiation, doesn't permit me to make out much.

    Thassssssit . . . . .



    73's de Edd
     
    Last edited by a moderator: Oct 21, 2017
  12. kevinm34232

    kevinm34232

    9
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    Oct 19, 2017
    R4= 392 ohms
    R5= 866 ohms
    YES
    470uF 25V cap, Yes GND
    L1
    12VAC
     
    Last edited by a moderator: Oct 21, 2017
  13. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    The circuits from D1 don't ohm out to the connector as L1 is bad (right?). But yes it continues down to R18 which is good 10 ohm resistor.
     
  14. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    Output voltage of VR1 is set to 4.0V.
    Dropping the voltage of D3 will get it down to 3.3V,that makes sense.

    If the input is 12VAC than D1 is most probably a Si rectifier diode.
    You have a half wave rectifier with the 470uF cap.

    The fact that D1 and L1 are blown means high current through them,we need to find out why:

    Can you please ohm(in diode test mode ,+ probe on test point) the cathode of D1 pad to GND,same for L1-L1a left side,and VR1 pin2.

    Do you have a DC power supply with controllable current limit?
    Can you test the 470uF cap?
     
  15. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    I can guess why.. we had a hurricane that came with major main power on and offs... My friend said the original transformer power supply was blown too...
     
  16. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    Ahhh,
    Well if you are lucky that didn't fry the all board.
    I would ohm the board as per #14.
    And than try to operate it with an external power supply(current limited!) of 12VDC connected between the cathode of D1 pad (positive) and GND.
     
  17. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    I have external current limiting DC Power Supply. I'm used to working on DC circuits, this is AC input, what is different here? (just a hobbyist here)..

    As far as I can tell from my normal limited experience, only D1 and L1/L1A are bad.. I have ordered D1 and will bypass L1 and see what happens with 1A current..

    And I very much appreciate all the help here by the way!
     
  18. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    The difference is that D1 and the cap rectify the AC to produce DC on the cap.
    You can connect the DC power supply (with D1 disconnected) directly to the cathode pad of D1(positive of PS) and gnd.
    Limit it, to say 200mA and check what you get:4volts at VR1 pin2,working board?
     
  19. kevinm34232

    kevinm34232

    9
    0
    Oct 19, 2017
    Yes sir will do thank you
     
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