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Discussion in 'Troubleshooting and Repair' started by jezzyjet, May 31, 2019.

  1. jezzyjet

    jezzyjet

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    May 31, 2019
    Hi there
    I have just started getting an interest in electronics and I have had a bit of success, I recently fixed the pcb board on my fridge freezer drinks dispenser by changing a diode that I could see was damaged, when it worked I was over the moon. anyway whilst repairing the ice flap on the fridge I was taking the cover off and the board shorted blowing one of the transistors(I think) and also heating up and possibly damaging some of the copper conductor strips on the rear, I would be really grateful of any assistance in tracing a new transistor and any other advice that you can give me as I feel totally gutted and I don't want to let it beat me especially after fixing it the first time

    Many thanks Jez pcb2.jpg pcb1.jpg
     
  2. jezzyjet

    jezzyjet

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    May 31, 2019
    Sorry forgot to add writing on the component says 0122 t404 600d mac
     
  3. Bluejets

    Bluejets

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    Oct 5, 2014
    First impression...wow, that is SOME blow up.
    Do you still have both hands and eyes..???

    Wonder how many times you have seen warning NOT to play with electricity.

    For your own protection I think best advice is to warn you once again and get an electrician to repair it.
    I doubt very much it will be just the one transistor and also they will simply replace the complete module.
    Then they will have to find what the real original problem was other than the one you have created.

    Another free lesson...... to be able to repair or attempt a repair, one first has to understand how it all works.
     
  4. 73's de Edd

    73's de Edd

    2,610
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    Aug 21, 2015
    Sir jezzyjet . . . . .

    My GAWD . . . .certainly you must have had the utter stupidity of starting to disassemble the unit in a power up condition ?
    I see several foil traces vaporized and seems like I see a touched/arc mark left on the A2 connected heat sink tab of the TRIAC / (electronic switch) on the top of the PCB.
    That unit is being :
    http://www.farnell.com/datasheets/8...8.1076227279.1559346572-1307427087.1559346572

    The touch spot /arc point is the VIOLET circle on the magged up ORANGE outlined inset photo. supposedly your boards metal shield touched to that point ?

    WHAT I AM A SEEIN' . . . . .

    On the same inset we see that the R12 gate . .wun hunna ohm . . . . drive resistor from the systems 28 pin u/p controller, probably using Q2 for driver interfacing, was not vaporized, so you might have squeaked out on that aspect, of any power backflow collateral damage.

    Just to the right side of the of the TRIACS Anode 1 terminal are two side by side heav-ee dood-ie push on wire connector terminals associated with what the TRIAC is switching power to.
    They are being GREEN rectangled over on the foil side of the board.
    Continuing on the larger foil side photo . . . the RED triangle is being the TRIAC connection points.
    Then, I can see bubbled up/vaporized foil in the HEAVY YELLOW lined up areas.
    At the far right there is placed an ORANGE mark up rectangle for a 9 pin Molex ? connector that has its pin 4/6 ? in FUCSIA that is going up to the top of the board and a large repair strip . . .FUCSIA mark up also . . . has been reworked across the top on that foil buss. Possibly, this having been done in the past ?

    BATTER UP ! . . . .

    Now . . . .time for you to inspect and ohm out measurents to see if the still INTACT end of the RED circle end of the YELLOW foil path is measuring ~zero ohms to A2 connection and then, also to A1 ? (To see if the TRIAC was / is zapped A1 to A2.
    ( If you are VEWY-VEWY-VEWY lucky . . . . the TRIAC may still be good because your errant touching position may have only put full AC line potentail ACROSS a circuitous foil pathway, and not having passed THRU any components .


    LASTLY . . . . . . . that boards foil side looks like . . . . . SCHEISS . . . . . ( icht bin der vurds uf Herr Kapp )

    I specifically refer to the extensively encircled GRAY areas.
    The site info is not telling me your country of origin . . . . so I don't know if you are 120VAC or 220VAC powered.
    Nor do I know your town / locale . . . . . but the board looks of frequent high humidity and possible airborne contaminant depositions in those areas . Onset of black mold ? black lung country ?

    Pull the board completely free and do a multiple 409 cleaning with a brush and thorough cleansing rinses 2 times then double lash a strong cord thru the corner hole, marked with the PINK circle, and then grab the cords end and strongly twirl the board around your head to then sling off most all of the water. Then finish a full dry with the heat of a hair drier.

    THEN you will EASILY and FULLY be able to evaluate the boards foil damaged areas.

    Now, tell me what other info you need . . . . .

    REPAIR ILLUSTRATION REFERENCING . . . . .


    [​IMG]



    73's de Edd . . . . .

    Why you should NEVER-NEVER- NEVER-EVER stand behind a fat lady when taking your group photo:

    https://i.pinimg.com/736x/a8/3d/e2/a83de2adf5b432c5b85a16afd4e8fe4c--so-funny-funny-shit.jpg


     
    Last edited: Jun 1, 2019
    Tha fios agaibh likes this.
  5. BobK

    BobK

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    Jan 5, 2010
    @73's de Edd the picture in your signature had me ROFL.

    Bob
     
    davenn, Bluejets and 73's de Edd like this.
  6. jezzyjet

    jezzyjet

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    May 31, 2019
    Hi there, Thankyou so much for your reply ,Im in the UK , I wasn't actually going to touch the board when it blew as I was only going to replace another item and somehow I caused a short and now im gutted!! , The repair at the very top of the board was me previously the board in my opinion had become damp and that strip looked corroded and one of the diodes legs had burnt out ,which I replaced and all was working well, What is 409 ? I have some isopropyl alcohol would that be any good? I will do as you say over the next few days and then get back to you, I hope I can repair this as the cost of a new part is around £200 ($252.00)which is a total rip-off if you ask me.Thanks again for your valued opinion ,,,Jez
     
  7. jezzyjet

    jezzyjet

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    May 31, 2019
    Hi there , Here is a couple of better photos with the rear of the board cleaned up, Thanks again !! Jez
     

    Attached Files:

  8. Bluejets

    Bluejets

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    691
    Oct 5, 2014
    A "straight on" photo of the bottom traces without any reflection would be better.
    Best arrangement is, set the board as in the component photo (good) then flip the board bottom to top and lay it in the same plane. Try not to get reflection or flash .

    At the top looks like TY2 has had it's lower right corner "blasted away".

    Also see pin 5 up from the bottom looks like it's had some mains contact modification so may well be some other damage associated with that which is not visible damage apart from the cooked traces (many) on the foil side. The not-so-good is the way that damage is leading straight to the (I imagine) micro controller chip.

    You STILL don't get the guts of the issue it seems. NEVER (as previously warned a couple of times) play with electrics.

    I think most would agree you are dammed lucky "THIS TIME".

    There are good reasons why these things plug in to the mains.
    Pulling the plug before working on internal components is one at the top of the list.

    Personally, I would call this now.
    User imposed damage as the cause.

    Others may soldier on though.
     
    Last edited: Jun 2, 2019
  9. Bluejets

    Bluejets

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    691
    Oct 5, 2014
    I had to Google that one....:)
     
  10. Martaine2005

    Martaine2005

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    May 12, 2015
    @BobK made me check the link too!. It took me 5 minutes to realize and then I cracked up!.
    What a brilliant unfortunate photo for both. Starting with him at the back, in big trouble with his wife. Her in the middle, in big trouble with her husband. And her in front, well, just big!
     
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