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Display Dim In HP L1955 19″ LCD Monitor

By on April 9, 2008

The complaint for this HP L1955 model HSTND-2B01 19″ LCD Monitor was dim display. After opened up the cover i saw some burnt mark at the inverter board. Further checking found 3 of the 4 C5707 push pull transistors shorted and front side puntured with a hole! No only that,  both the p-channel FET D10PF06 also shorted and have some burnt mark in it too. The inverter fuse already open circuited!

Since i do not have the original of the D10PF06 I used an equivalent part number to test it out. I switched “On” the display and it shutdown after 1 to 2 seconds! I thought it could be the backlight problem didn’t realized that it was the substitution part number that gave problem. I used  a 15″ LCD Monitor to test out the 19″ backlights (4 backlights) and proven all of the backights were working fine.

hp lcd monitor

The stock that i have FQU11P06 already used up and can’t test the set. I ordered it yesterday and got it today. I took out the replacement number and put in the FQU11P06  PCHANNEL FET, the set came back to life! I have tested it for a while and was not hot to touch. I will run the full test again under Windows high resolution-hope everything is okay.

Conclusion-a wrong replacement of the p-channel FET may lead you think that it was the backlights or inverter IC fault. If possible get the original part number.

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8 Comments

  1. Jose E. Kunhardt

    September 11, 2009 at 8:41 am

    I am working on the same monitor but i have no idea how to identify if the c5707 push pull transistors are burnt, i dont see any bulging on the transistors. i should clarify that i dont get a dim display on this unit but a black screnn with a resposive power button and power switch.

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  2. admin

    September 11, 2009 at 9:32 pm

    HI Jose,

    You need to remove the transistor and test it with meter.

    Jestine

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  3. Kazi Baki

    March 31, 2010 at 4:01 am

    Dear Jestine,
    I have Philips 17 inch LCD, model 107s, allways show popup, attention
    monitor control system locked, this model is common problem,pls say some thing about this
    thanks

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  4. admin

    March 31, 2010 at 9:12 am

    HI Kazi,

    I guess you may have to reprogram the EEprom IC.

    Jestine

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  5. Williams Adebowale

    September 7, 2010 at 6:36 am

    I am working on this same Monitor, but can't display on the screen

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  6. admin

    September 7, 2010 at 6:54 am

    HI William,

    Is all the output voltages good from the power supply? Does the inverter ic have any supply voltage?

    Jestine

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  7. Hassan

    August 12, 2012 at 11:57 am

    Dear Jestine,

    I have hp Lcd model L1955 and problem is that i have found some noise from chopper transformer which result that i hear same sound from my pc speaker.Kindly give me the solutions.

    Hassan

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    • Jestine Yong

      August 14, 2012 at 1:19 am

      Hi Hassan,

      Noise usually comes from inductor or transformer. Try open up the monitor and gently know the inductor/transformer with the handle of the screw drive to see if the sound will go away or not.

      Jestine

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