How can i find the bad component on this

Discussion in 'Test & Measurement Forum' started by Hornet2121, Jan 20, 2019.

  1. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Washing machine control board
    Shows red led ready.
    but when I push start nothing happens.
    Iv Tryed another door interlock no joy was told the boared was bad
    Iv Tryed diffrent settings ie drain spin wash cycles nothing.
    I cant see any black components.
    When I pushed start when it was connected it tripes electrics sometimes. Im convinced its a component on the boared like a starting component bit have no idea what im looking at as I dont have any schamatics.
    Is there any way to put voltage in and test with compressed air spray.
    If so how would I do it?
    Where can inconnect ground and a live to put a voltage into it safe.
    Also what voltage is a safe voltage.
    Any steps to quickly diagnose this issue will be helpfull.
     
  2. jpanhalt

    Expert

    Jan 18, 2008
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    THAT is go'ng to require a lot of effort. Are you up to it? Do you have the schematic or factory trouble shooting guide available?

    If not, try to find a used machine of the same model. Swap PCB's, and then resale the old one.
     
  3. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Yeah id rather scrap it than buy the board mate.
    It surly cant be that difficult just a bunch of smds could a bad cap stop it starting.
    How in theory could I fix this with out unsoldering testing every bit.
     
  4. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Sorry not fix it licate the bad part or parts
     
  5. jpanhalt

    Expert

    Jan 18, 2008
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    Why locate the bad parts, if you don't intend to fix it?
     
  6. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
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    It surely can. One of those smd's is a microprocessor. It could be testing the status of a dozen things, both on and off the board, before allowing the machine to run. Unless it is the uC that has failed...

    ak
     
  7. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Sorry yes inwant to fix it
    I buy sell used kitchen appliances
    If I can fix component level boareds id make a lot of money lol
    Plus im an enthusiast and it intrests me.
     
  8. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Is there any way to test with out schemarics.
    Id of thoufht it was just I timer circuit
    Type switching the relays on and off for set amount of time
     
  9. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    It's going to have sensors for temperature, water level, perhaps motor speed, and no doubt a few more. If it detects a problem it won't run.
    Do you know what sensors are connected to the board and where?
     
  10. Externet

    AAC Fanatic!

    Nov 29, 2005
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    To repair a clotheswasher or anything, you must learn and know how the machine and the board works. Otherwise it is just guessing.
    Service instructions and schematics are mostly inside the control panel or attached at the back, or at the web.
     
    Last edited: Jan 20, 2019
    Reloadron likes this.
  11. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    I think iv located the faulty smd chip
    Any one no where I can find a replacment
    Reason I think its faulty it was very hot burning to the touch when I hooked it uptoday.
    Probs not the best idea iv had sticking my fingers in a power boared
    Lol.

    Says Uln2003ag pwfe 10

    Also does anyone no why this chip could stop it starting on all cycles.
     
  12. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
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    The ULN2003 is a driver transistor array with 7 individual elements.

    http://www.st.com/resource/en/datasheet/uln2003.pdf

    It is overheating because either one (or more) of its transistors has failed, or because something it is driving has failed. Replacing the chip is a start. If that does not solve the problem, you'll have to trace out where each of its outputs go.

    ak
     
  13. absf

    AAC Fanatic!

    Dec 29, 2010
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  14. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Yeah the bottom one you have highlighted
    I looked on ebay cant find any with ag on the end.
    Will check yours out now hopefuly thats them
    Im after Uln2003ag
    Pwl10
     
  15. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Nice one thats the part I need
    Thank you been on hours looking for that chip lol
     
  16. absf

    AAC Fanatic!

    Dec 29, 2010
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    ULN2003A are very common NPN darlington drivers.

    The plane ULN2003A are in DIP package and the SMD ones are denoted by "AG" or ULN2003D as in the ST datasheet.

    Allen
     
  17. BobTPH

    Senior Member

    Jun 5, 2013
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    I suspect that when you replace the chip, you will have a board with a new chip that gets hot and the board still does not start up. Depending on how hot it is getting, it might even be normal for it to get hot. If there is something wrong causing it to get hot, it is most likely a short somewhere else.

    Bob
     
  18. Hornet2121

    Thread Starter New Member

    Jan 20, 2019
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    Thanks for info been a huge help going toorder the part now and hopefully it will fix it if not back to the drawing boared.
    Best order a few lol.
     
  19. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    It looks like no one has asked you to post the make and model of the machine. Can you do that?

    Ken
     
    absf likes this.
  20. ian field

    AAC Fanatic!

    Oct 27, 2012
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    There may well be pattern spares outfits that do boards for (slightly) less than the price of a new washing machine - but there are various sensors that signal the board when to proceed to the next item on the wash cycle. Any one of them could be; "rain stops play". You wouldn't believe the number of people cough up for a new board - then find out its a knackered heater...………..
     
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