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Gateway FDP1960 wont power up / strobe light effect

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    Gateway FDP1960 wont power up / strobe light effect

    Hi guys I have a LCD here which wont power up. My assumption was that the inverter board has a problem so today I had some time and took it apart. I found the main fuse blown (which was jumped for time being) as well as 2 bad caps. I went ahead and replaced all caps just to make sure. After that I was going to test the screen and got presented with a strobe light effect. As soon as the screen is plugged in to the power outlet it starts blinking. The power button led is not lit and I do not have a clean 5VDC going to the video board. The 12VDC seems to be between 11.7VDC and 12.08VDC. Do you guys have any ideas where to start checking more into this or maybe somebody experienced this already?
    Attached Files

    #2
    Re: Gateway FDP1960 wont power up / strobe light effect

    Check mosfets U301 and beside him, cant se num. , probably U341.

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      #3
      Re: Gateway FDP1960 wont power up / strobe light effect

      Originally posted by HITandRUN View Post
      The power button led is not lit and I do not have a clean 5VDC going to the video board.
      1) What brand and series did you use for replacement capacitors?

      2) Did you replace the little capacitor just below and to the right the big yellow SMPS transformer?

      3) What do you mean by "clean" 5V DC? Is is fluctuating? Is the voltage significantly below 5V DC?
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        #4
        Re: Gateway FDP1960 wont power up / strobe light effect

        First of all thank you for your responses and please go slow with me since I'm new to troubleshooting on component level. Also I tried to replaced the lousy cell pictures with some better camera shots in the OP but there is no edit button so I have them in this post.


        Originally posted by kbrletic View Post
        Check mosfets U301 and beside him, cant se num. , probably U341.
        U301 and U302 are ENHANCEMENT MODE POWER MOSFETS. Do I need to desolder these to check for functionality?

        Originally posted by retiredcaps View Post
        1) What brand and series did you use for replacement capacitors?

        2) Did you replace the little capacitor just below and to the right the big yellow SMPS transformer?

        3) What do you mean by "clean" 5V DC? Is is fluctuating? Is the voltage significantly below 5V DC?
        1. The original caps were Samxon GF(M) 105*C8 and I replaced them with NTE 105*C. I know everybody says get good caps etc. but this is what was available locally. Also I assume the original caps were pretty cheap brand as well and made it for a few years so my thinking is some other cheap crap should fire the screen for at least a week right?

        2. No i didnt replaced this one yet hence the green color opposed to blue (new caps)

        3. The voltage is fluctuation up and down. I can hear the inverter ramping up and shutting down. I assume the voltage is going up and down attune with the sound of the inverter. The voltage is between 2.5 and 4 but its hard to measure at this point since its cycling pretty quick.
        Attached Files
        Last edited by HITandRUN; 03-27-2011, 08:41 AM.

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          #5
          Re: Gateway FDP1960 wont power up / strobe light effect

          Originally posted by HITandRUN View Post
          Do I need to desolder these to check for functionality?
          Check them for shorts "in circuit" first. If any reading is below 30 ohms, then desolder them and retest them out of circuit.


          1. The original caps were Samxon GF(M)
          Samxon GF are a problematic series.

          2. No i didnt replaced this one yet hence the green color opposed to blue (new caps)
          That little green cap plays an important part of the SMPS startup process. This cap could be causing the 5V rail not to start up properly (i.e. fluctuation). I suggest using a quality cap like a Panasonic FR, FM, or FC for a replacement.

          While the NTE caps are likely to work, the SMPS requires low ESR (ohms) caps. If the NTE caps are low ESR, you are okay. If not, the lcd is likely to work, but dont' be surprised if you are changing out the caps again in 6 to 12 months.

          The Samxon GF caps are low ESR, but they are a problematic series (lemon).

          PS. The pictures are a significant improvement.
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          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

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            #6
            Re: Gateway FDP1960 wont power up / strobe light effect

            those NTE caps look suspiciously like Teapo/Yageo (star vent)

            Comment


              #7
              Re: Gateway FDP1960 wont power up / strobe light effect

              Originally posted by retiredcaps View Post
              Check them for shorts "in circuit" first. If any reading is below 30 ohms, then desolder them and retest them out of circuit.



              Samxon GF are a problematic series.



              That little green cap plays an important part of the SMPS startup process. This cap could be causing the 5V rail not to start up properly (i.e. fluctuation). I suggest using a quality cap like a Panasonic FR, FM, or FC for a replacement.

              While the NTE caps are likely to work, the SMPS requires low ESR (ohms) caps. If the NTE caps are low ESR, you are okay. If not, the lcd is likely to work, but dont' be surprised if you are changing out the caps again in 6 to 12 months.

              The Samxon GF caps are low ESR, but they are a problematic series (lemon).

              PS. The pictures are a significant improvement.
              Thank you for all your pointers! I'll get some quality caps and replace the one mentioned by you as well.

              Comment

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