SMD identification - F & P fridge - Help needed

Discussion in 'General Electronics Chat' started by parklev, Jul 1, 2011.

  1. parklev

    Thread Starter New Member

    Jun 29, 2011
    1
    0
    Hi everyone,

    I have a faulty Fisher and Paykel refrigerator I am determined to fix ( Model E411T). In the middle of the night the fridge would start beeping and wouldn't stop. I have read many forums that say the fault is attributed to a faulty fan however I tested both the freezer and the fridge fan (with a 12v battery) and they were working correctly.

    I have tracked the fault to an surface mount component on the circuit board that is in the path that drives the negative line of the refrigerator compartment fan. The component has the markings HJ and 2Z9. I have done a fair bit of searching to track down what this component is but have had no luck.

    If anyone could help me it would be much appreciated.

    below is a link to an image of the board, the damaged component is circled. The component to its right is identical but drives the Freezer compartment fan.

    http://img34.imageshack.us/img34/2702/fridgecircuitboard.jpg

    thanks in advance

    Regards
     
  2. DimmeysJeff

    New Member

    Sep 16, 2011
    1
    1
    I have the same fridge with the same problem, but I just fixed it -permanently.on that circuit board there should be a black circular component about an inch in diameter. That's the speaker that does all the beeping. De-solder that off the board and all your woes will be gone. Of course, you'll no longer have a 'door open' warning, but it's a small price for not dealing with a beeping fridge at 3 in the morning.

    Be careful... There's mains power on that circuit-board...
     
    ErnieM likes this.
  3. Multiplication

    New Member

    Oct 21, 2011
    3
    0
    As far as I can see, it's just an NPN power transistor. There is a 3.3K resistor in series with the base, and a 1.0 ohm resistor in the emitter to sense the current. It operates at under 20 V, so any power transistor that fits should do to replace it. Although it is possible that they drive the transistor in a linear fashion, but then hopefully they don't relay on the gain of the transistor, and use the feedback resistor to set a selected current. I'm about to go and replace one of mine; I blew the freezer transistor (just to the right of yours). The reason: the fan wires were badly chafed, and must have shorted out. The transistor was discoloured from heat, and the plastic package was cracked. If yours is similar, you should check for shorted fan wires as well. Mine had insulation rubbed off at many places, so they have a lot of tape on them now. M.
     
  4. Multiplication

    New Member

    Oct 21, 2011
    3
    0
    Though very high gain; over 1360 according to my cheap multimeter. The replacement I got for its neighbour comes in at only 250 or so, so that could be a problem.
     
  5. Multiplication

    New Member

    Oct 21, 2011
    3
    0
    It seems that they do rely on the gain of the transistor. In fact, the replacement immediately got very hot, quickly shooting to over 80 degrees C. I ended up having to reduce the 3K3 base resistor by paralleling it with an 820 ohm resistor. This seemed to cause similar fan voltage for various fan voltages from the micro. So this seems to be why my emergency fix last night didn't work. I put in an old TO220-like transistor I had lying around, and whose gain would have been far less than a thousand. It didn't get too hot, but didn't turn the fan on much either. So while parts of the freezer were OK, others were only just below freezing. The main cabinet (fridge part) didn't get much below 10 degrees Celsius (50 degrees Farenheit). Now with the extra base drive, the freezer fan runs harder, and that seems to be needed before the micro will turn on the fridge fan. I won't know till tomorrow if everything is right.
     
  6. #12

    Expert

    Nov 30, 2010
    16,347
    6,835
    Go to page 16 of this "chat" forum and look for the frowny face, "GE refrigerator failures update" by #12
    Last post dated 9/25/2011

    Your refrigerator has the adaptive defrost that the GE refrigerators have. You might find that post informative...or not.
     
  7. Lundwall_Paul

    Member

    Oct 18, 2011
    220
    19
    I would see if there is a newer revision for this board. This board should have gone through layout and re-spun before it went into production. I would not be surprised if they had
    many, many repairs on this layout. Perhaps the manufacture has since done that.
     
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