[SUCCESS] P377SM-A 4K Display Upgrade

Discussion in 'Sager and Clevo' started by DARCODER, Jan 7, 2016.

  1. Meaker@Sager

    Meaker@Sager Company Representative

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    It's not something we would offer on an older model anyway, but it's always good to get confirmation if other users feel like giving it a go.
     
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  2. aarpcard

    aarpcard Notebook Deity

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    To fix the flicker, try putting more decoupling capacitance on the 3.3V rail.
     
  3. Rikoshet

    Rikoshet Notebook Enthusiast

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    Hello guys!
    Followed this thread to upgrade my laptop with some degree of success:

    http://forum.notebookreview.com/threads/p377sma-4k-display-upgrade-waiting-for-parts-to-test.786555/

    The thread is closed now that's the reason of this one.
    I'm calling for guys who had success in the old thread to help me: DARCODER, aarpcard, khenglish, akaraah, t456

    I have bad flickering and then black screen, please take a look and suggest:

    https://drive.google.com/open?id=1oKYs5WwfAdznrioZ04QMx0hU2Zvq_x7S

    the voltage on LCD is 3.23v. I read all 12 pages and tried all suggestions from other users. Decoupling capacitor didn't work on 3.3v rail. I used a 3300uF capacitor.

    Taping the LCD so it didn't touch the hinge didn't work since there is a connection of LCD metal part with GND through the LCD cable. Without the cable the is no connection between the LCD and hinges, I have a multimeter for that.

    I was disparate an bough another LCD from eBay, it also flickers.

    Guys, please help to bring to the life this laptop! Thanks in advance!
     
  4. Khenglish

    Khenglish Notebook Deity

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    That looks like you are getting interference on the eDP cable from the motherboard. Do you have any exposed sections of the cable that are not covered in EMI tape?

    A test for this is to drop the refresh rate using the custom resolution tool in the Nvidia control panel. If 60 Hz mostly works, you'll probably be fine at 40 to 50 Hz.
     
  5. Rikoshet

    Rikoshet Notebook Enthusiast

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    Just tried. I'm on mac, used a mac specific utility. Have only 3 options: 48/50/60HZ. When switching HZ the screen goes black...
    Do you remember if with 5v there issues? Maybe I can try it.
     
  6. Khenglish

    Khenglish Notebook Deity

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    5V will work but you will have some display issues. Screens are usually rated for up to 4V before strange things happen.
     
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  7. aarpcard

    aarpcard Notebook Deity

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    I looked at the video. Did you by chance alter the length of some of the EDP channel wires? I had the exact same artifacting when I accidentally cut an EDP channel twisted pair while making my cable and soldered it back together. Display port uses differential pairs and has very tight timings which means the length of the wires matters. Signals traveling on shorter wires will arrive just before signals traveling on longer wires. This is enough to drive one of the channels out of phase from the others. Depending on the severity you will get artifacting like you exhibited or the screen won't even turn on. I had to lengthen the two wires I cut and repaired to closely match the other 3 channels. The tolerances are very tight - I got mine to within 1mm and that cleared up the artifacting.
     
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  8. Rikoshet

    Rikoshet Notebook Enthusiast

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    Thank you guys for answering me! Appreciate it, really!
    Yes, I messed up with wires... Do you think, @aarpcard, if I solder a little piece of wire I can adjust it? Or better taking new cable?
    Thanks!
     
  9. aarpcard

    aarpcard Notebook Deity

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    That's what I did and it worked out. You just have to make sure the lengths of all 4 twisted pairs are pretty near identical. Also, if you are soldering wires to extend a twisted pair, use the same length of wire for each side of the pair. Not doing so will likely mess up the differential signalling.
     
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  10. Khenglish

    Khenglish Notebook Deity

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    On my cable the twisted pairs are all within a few mm of each other in length. I have the same number of solder points per line (one), but the solder points are at different points.

    Making sure all wire was shielded was 100% necessary. Before I added the aluminum tape I would have periodic function like you have.
     
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