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Laptop fan not work

Discussion in 'Troubleshooting and Repair' started by grazkas, Jun 27, 2017.

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  1. grazkas

    grazkas

    2
    0
    Jun 27, 2017
    Hallo laptop fan not work.
    Work when short between VIN and VO.
    Please help fan-1.png fan-2.png
    2 pic is KB926QFA1_LQFP128 chip
     
  2. 73's de Edd

    73's de Edd

    2,922
    1,235
    Aug 21, 2015
    Sir grazkas . . . . .


    G993P1UF . . . . . . Linear Fan Driver

    As it should . . .when you apply 5VDC DIRECTLY from the 5vdc supply (from pin 2) to the fan (pin 1 )

    Do you have a high logic level coming into pin 4 ?

    If not, touch a leaded 1k resistor from pin 1 or 2 over to pin 4 and see if the fan starts.

    If it does, your problem is related to receiving HI enable logic from the EN_FAN1 buss.

    73’s de Edd
     
    Last edited by a moderator: Jun 28, 2017
  3. grazkas

    grazkas

    2
    0
    Jun 27, 2017
    Into pin 4 comes 0,1 V when connecting resistor from 1 to 4 fan starts. You say that guilty are KB926QFA1_LQFP128 controller
     
  4. 73's de Edd

    73's de Edd

    2,922
    1,235
    Aug 21, 2015
    Sir grazkas . . . . .

    Your performing the test given, confirms your fan driver chip as being OK.

    You are just missing that “ EN_FAN1 “ logic level high to enable the fan.

    You have not told me what brand and model number unit you have, but somewhere in its construction should be some analog digital conversion. I am showing you two aspects of a Lenova / IBM that has the handshaking between the analogics of a 100K thermistor mounted at the u/p heatsinking and its connection to the input of a LM393 comparator. At a specifically established overheating threshold the unit flips logic states and can engage the fan or even shut the computer down if cooling does not meet a required recovery time specification.

    The other aspect is the battery temperature specification which is sampled from the battery and accomplished by the similar bottom circuitry.

    Looking at your units circuitry, you should find ITS related circuitry to evaluate.

    If your unit is using the KB926QFA1_LQFP128 family of u/p I would expect fan / temp interfacing being related to connecting into its pins
    70, 71,5,28, 25, 19 and 29.

    OR Your supplied sheet is showing pin 70 as the fan output digital drive line. . . .I can’t see the u/p’s left half connections for any further evaluation..

    Referencing to:

    Your supplied top FAN1 Conn BLUE square inset, at its bottom right corner has the possibility of the 1 connection being +5VDC power and 3 connection ground and the center 2 being the analog output from a remoted mounting solid state temperature sensor.

    Typical Potential Analog Digital Interfacing Examples:

    [​IMG]

    Aside . . . .

    Is there the possibility of this unit as having received lots of use and heating up over a period of time.

    A common fault, is for there INITIALLY being a good moist slurry coating of tin oxide and silicone grease under the u/p and providing GOOD thermal mating to the heat sink.

    With time- heat and use, the silicone grease will creep laterally and leave a resultant floating dry oxide powdery layer, it actually is now being an insulator, and introducing a severe decline of efficient thermal transfer / cooling..

    73’s de Edd
     
    Last edited by a moderator: Jun 28, 2017
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