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  1. #1
    Soundwave
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    Weird behaviour of T100 after trying microHDMI to vga adapter

    I have, by mistake, plugged in an active hdmi to vga adapter without giving it the extra power by the micro USB port. Strangely enough it worked the first time (the tablet was getting extra juice from the AC, maybe that has to do with it).
    After trying it I was slowly unplugging it, and here the weird part starts:
    As I was half was out with the micro HDMI connector the tablet shutdown and refused to turn back on. I unplugged everything and still nothing, it turned back on only after I reconnected the power cable.
    After this I retried the adapter (still without the extra power to it) and everytime I reached the bottom of the micro HDMI connector pushing the cable in the screen started to do BIG glitches ( black screen, and some weird noisy rectangles repeated over the screen). To get away from them I always had to force shutdown and unplug everything and make it turn back on with the charger.
    Finally I realised that the adapter was active so I plugged an USB charger into it and now it functions properly again but the issue that I'm confronting with is on the tablet side.

    In the lower right part on the back I feel it hot (even without anything else connected to it) and the power consumption is 3X higher even in idle state ( it used to consume something lower than 3W now it consumes 10W with the same load scenario). I went checking the temperatures. The CPU runs normal (38-41°C) but the GPU runs constant at 50°C. In fact, after a couple of minutes Intel DPTF goes crazy and underclocks the CPU to 0.5 GHz (same behaviour if one goes at 10% of charge) to avoid overheat, but that's insane as the CPU is still "cool". ( It does in fact lower the maximum temperature for the cores).

    And insights on this?
    Any solutions?
    Thank you for reading!

    Inviato dal mio XT1575 utilizzando Tapatalk

  2. #2
    Super Moderator
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    There's several threads here about this issue. Here's one,

    Messed up screen due to VGA adapter

    You've likely killed your T100. Sorry man.
    Rick, loving my T100TA-C1-GR Z3740 64GB Win 10
    BIOS 314. All Windows updates except Bing. All Asus Live Updates. WIFI driver 5.93.99.210
    I get 8-12 hrs use per charge using SLEEP mode. Warning, NEVER calibrate the touchscreen.
    When posting for help, please include Your Model Particulars
    Casters T100 Master Help Guide

  3. #3
    Soundwave
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    Thanks for the answer

    Inviato dal mio XT1575 utilizzando Tapatalk

  4. #4
    Jazz
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    Quote Originally Posted by ban.codrut View Post
    I have, by mistake, plugged in an active hdmi to vga adapter without giving it the extra power by the micro USB port. Strangely enough it worked the first time (the tablet was getting extra juice from the AC, maybe that has to do with it).
    After trying it I was slowly unplugging it, and here the weird part starts:
    As I was half was out with the micro HDMI connector the tablet shutdown and refused to turn back on. I unplugged everything and still nothing, it turned back on only after I reconnected the power cable.
    After this I retried the adapter (still without the extra power to it) and everytime I reached the bottom of the micro HDMI connector pushing the cable in the screen started to do BIG glitches ( black screen, and some weird noisy rectangles repeated over the screen). To get away from them I always had to force shutdown and unplug everything and make it turn back on with the charger.
    Finally I realised that the adapter was active so I plugged an USB charger into it and now it functions properly again but the issue that I'm confronting with is on the tablet side.

    In the lower right part on the back I feel it hot (even without anything else connected to it) and the power consumption is 3X higher even in idle state ( it used to consume something lower than 3W now it consumes 10W with the same load scenario). I went checking the temperatures. The CPU runs normal (38-41°C) but the GPU runs constant at 50°C. In fact, after a couple of minutes Intel DPTF goes crazy and underclocks the CPU to 0.5 GHz (same behaviour if one goes at 10% of charge) to avoid overheat, but that's insane as the CPU is still "cool". ( It does in fact lower the maximum temperature for the cores).

    And insights on this?
    Any solutions?
    Thank you for reading!

    Inviato dal mio XT1575 utilizzando Tapatalk
    As rick mentioned, this has happened to other users, but I think for the other use their screen was stuck in an inoperable state while yours seem to be still functional?

    In the Intel HD Graphics utility, there's an option to set power consumptiom to maximum battery vs maximum quality. I've never played with that slider before but that's what I would try to play with first.

    if I were you I'd want to make sure there isn't some software process that's chewing up resources. I know your CPU activity is low but just to be sure right? Is there any background tasks running?

    And, is the heat and high drain occurring even when the display is off? If so, maybe you can leave it "sleeping" for 10-15 minutes, then use sleepstudy as another way to see what hardware is drawing power.

    Finally, what if you uninstall the video driver and reboot, in order to force a reinstall of the driver? Maybe the device is keeping the GPU at full-blast after your VGA adapter was used for whatever reason. In that case, maybe reinstalling the driver would work?

    Keep me posted; curious to see what happens. I've used both cheap micro-HDMI to VGA and HDMI adatpers (the former for a week in a row) from eBay and I never had any of the troubles others have been experiencing. Mind you, I also had a laptop cooling pad to make sure my temps were low.
    Last edited by felixdd; 06-26-2016 at 10:03 AM.

  5. #5
    Soundwave
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    Quote Originally Posted by felixdd View Post
    As rick mentioned, this has happened to other users, but I think for the other use their screen was stuck in an inoperable state while yours seem to be still functional?

    In the Intel HD Graphics utility, there's an option to set power consumptiom to maximum battery vs maximum quality. I've never played with that slider before but that's what I would try to play with first.

    if I were you I'd want to make sure there isn't some software process that's chewing up resources. I know your CPU activity is low but just to be sure right? Is there any background tasks running?

    And, is the heat and high drain occurring even when the display is off? If so, maybe you can leave it "sleeping" for 10-15 minutes, then use sleepstudy as another way to see what hardware is drawing power.

    Finally, what if you uninstall the video driver and reboot, in order to force a reinstall of the driver? Maybe the device is keeping the GPU at full-blast after your VGA adapter was used for whatever reason. In that case, maybe reinstalling the driver would work?

    Keep me posted; curious to see what happens. I've used both cheap micro-HDMI to VGA and HDMI adatpers (the former for a week in a row) from eBay and I never had any of the troubles others have been experiencing. Mind you, I also had a laptop cooling pad to make sure my temps were low.
    I have already done what you suggested (GPU driver + sleep). Letting it to sleep does nothing as the SoC's area is not cooling at all. Another observation is that if I put the hot area next to my ear I can hear like a static sound, variating not continuous, so that has to be some bad tension going on there. As I see it the causes of the sound could be: malfunction of voltage regulator(fixable) malfunction of the SoC itself( trashing it is the best solution here).

    I still have to try two more soft solution:1st is to do a sleep study as you suggested even tho I have low hopes for any useful data; 2nd booting another os (Linux?) and see if it behaves the same.

    After that I will open it up and inspect the insides near the SoC and the HDMI connector. Maybe something moved and is making some sort of short as the plug was a bit hard to stick it inside at first (best case scenario).

    I will use this thread to keep a sort of log of what's going on, but after the 6th (exams)

    Inviato dal mio XT1572 utilizzando Tapatalk

  6. #6
    Jazz
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    Quote Originally Posted by ban.codrut View Post
    I have already done what you suggested (GPU driver + sleep). Letting it to sleep does nothing as the SoC's area is not cooling at all. Another observation is that if I put the hot area next to my ear I can hear like a static sound, variating not continuous, so that has to be some bad tension going on there. As I see it the causes of the sound could be: malfunction of voltage regulator(fixable) malfunction of the SoC itself( trashing it is the best solution here).

    I still have to try two more soft solution:1st is to do a sleep study as you suggested even tho I have low hopes for any useful data; 2nd booting another os (Linux?) and see if it behaves the same.

    After that I will open it up and inspect the insides near the SoC and the HDMI connector. Maybe something moved and is making some sort of short as the plug was a bit hard to stick it inside at first (best case scenario).

    I will use this thread to keep a sort of log of what's going on, but after the 6th (exams)

    Inviato dal mio XT1572 utilizzando Tapatalk
    If you're hearing intermittent buzzing then I wouldn't even bother with sleep study. My money would be a short or some sort of hardware issue.

    If I was in your shoe and am planning to do an open repair, I would let the device run its batteries completely flat. True it harms the Li-Po battery, but what you have right now is a fire hazard. You don't want there to continue to be voltage and heat across the malfunction

  7. #7
    Soundwave
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    I have found the "bua" of the issue, the root of the problem :

    [HIDE][/HIDE]
    Picture

    This little IC from ROHM deals with the Power Management for the Atom processor and all the north bridge...
    This little fella lights up to high temperature as soon as I turn on the machine (questions of seconds). And the GPU heats up because of that and not due to high unexplained load.

    This is what Asus called a motherboard malfunction back in the days when they still did warranty replacements for the T100...
    I will try and hunt for it on e-commerce and replace it... sad enough there is no public datasheet for the IC.

    Inviato dal mio XT1572 utilizzando Tapatalk
    Last edited by ban.codrut; 07-13-2016 at 09:29 AM.

  8. #8
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    Hope you have access to specialized equipment to R&R BGA ICs. This is not a job the average person can do. Of course if the mobo is dead, nothing really to loose.
    Rick, loving my T100TA-C1-GR Z3740 64GB Win 10
    BIOS 314. All Windows updates except Bing. All Asus Live Updates. WIFI driver 5.93.99.210
    I get 8-12 hrs use per charge using SLEEP mode. Warning, NEVER calibrate the touchscreen.
    When posting for help, please include Your Model Particulars
    Casters T100 Master Help Guide

  9. #9
    Jazz
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    Hey any updates?

  10. #10
    Jazz
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    Soo...an update on my end.

    I have the same problems now
    . SOC region over-heats, burning up energy despite connective standby working. CS shows an "unknown" process burning through most of my battery, which is draining at about 1% per 1-2min while sleeping. Buzzing sound through the VGA port.

    The difference is I did not use the VGA port recently. Nor do I have any graphical glitching that you're experiencing. Nonetheless, this renders my tablet quite limited in function -- my battery life has now gone from 10h, to 3-4 hours at best.

    I'm wondering whether others have experienced this. I'm going to see whether my warranty is still valid....

 

 
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