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X1C3 display flashes???

X1/X1-Carbon series specific matters only
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RealBlackStuff
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Re: X1C3 display flashes???

#31 Post by RealBlackStuff » Sat Apr 22, 2017 10:12 am


pgoelz
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Re: X1C3 display flashes???

#32 Post by pgoelz » Sat Apr 22, 2017 3:32 pm

Hey, aluminum foil works to stop the aliens communicating with me when I put it on my head, so why not ;)

Trouble is that merely putting it on the back of the display lid isn't enough. If my suspicion is correct, it is the WiFi itself that is disturbing the display. Since the antennas are IN the lid, it would require shielding on both sides of whatever was affected.... as well as some way to bypass the RF from entering via the wiring.

My next experiments will be to see if I can isolate WHICH of those three settings is the important one. My money is on "panel self refresh" or possibly "display power saving technology". However, it is relatively unimportant at this point. I don't use the machine very extensively on battery so getting the absolute ultimate battery life is not my #1 priority.

Paul
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Re: X1C3 display flashes???

#33 Post by pgoelz » Wed Apr 26, 2017 9:58 am

I restored my old Thinkpad X61s image to a partition on the X1C and after some struggling convinced it to boot and update itself. Same issue as on Windows 8.1 and 10. However, unlike on Windows 10, Windows 7 and 8.1 flash while attempting to connect to a weak AP but the display does not enter the continuous flashing state. No idea if that means anything and Lenovo still is not talking.

Paul
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Re: X1C3 display flashes???

#34 Post by RealBlackStuff » Wed Apr 26, 2017 11:22 am

I'm still not convinced about the built-in wifi-card.
It's one of the followingl:
• 11b/g/n, Intel Wireless-N 7265, 2x2, Wi-Fi + Bluetooth combo adapter, M.2 card
• 11a/b/g/n, Intel Dual Band Wireless-N 7265, 2x2, Wi-Fi + BT adapter, M.2 card
• 11ac, Intel Dual Band Wireless-AC 7265, 2x2, Wi-Fi + BT adapter, M.2 card

If you have a wifi On/Off switch, switch it Off, then try an El Cheapo USB wifi-N dongle, just to check.
Something like this: http://www.ebay.com/itm/262728195951

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Re: X1C3 display flashes???

#35 Post by pgoelz » Wed Apr 26, 2017 11:33 am

RealBlackStuff wrote:I'm still not convinced about the built-in wifi-card.
It's one of the followingl:
• 11b/g/n, Intel Wireless-N 7265, 2x2, Wi-Fi + Bluetooth combo adapter, M.2 card
• 11a/b/g/n, Intel Dual Band Wireless-N 7265, 2x2, Wi-Fi + BT adapter, M.2 card
• 11ac, Intel Dual Band Wireless-AC 7265, 2x2, Wi-Fi + BT adapter, M.2 card

If you have a wifi On/Off switch, switch it Off, then try an El Cheapo USB wifi-N dongle, just to check.
Something like this: http://www.ebay.com/itm/262728195951
It is the Intel Dual Band Wireless AC-7265. The issue is present on Windows 7, 8.1 and 10. It is worst on Windows 10 but it flashes on all three OS versions. I don't have Linux installed right now (removed it to make room for Windows 7) but I could try that at some point to get entirely away from Windows.

As I reported earlier, I have tried a USB dongle with the 7265 turned off. The screen did not flash with the dongle located away from the display but it DID flash if I held the dongle to the back of the lower left corner of the display. It might be coincidence.... or not. The behavior was identical to what happens with the built in adapter including developing into continuous flashing and eventual black screen.

I would love to try another WiFi adapter but I have not been able to find a list of whitelisted adapters. Are the other two you mentioned usable / whitelisted in an X1C3?

Paul
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Re: X1C3 display flashes???

#36 Post by RealBlackStuff » Wed Apr 26, 2017 12:34 pm

Those 3 are listed in the frubom/partslist of the X1C3: http://download.lenovo.com/parts/ThinkP ... 150106.pdf
So they are "whitelisted".

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Re: X1C3 display flashes???

#37 Post by pgoelz » Thu Apr 27, 2017 7:58 am

For anyone following this issue here.... I just posted this on the Lenovo forum. I hope cross posting it here is acceptable.

#############################

OK, I think I am zeroing in on a mostly acceptable solution. No thanks to Lenovo or Intel.

Since I can stimulate the issue at will with an external RF field from a 2W 433MHz transmitter, it makes it easy to explore solutions and be fairly confident that they are in fact 100% effective. Remember, this external RF field EXACTLY duplicates the flashing screen I sometimes get when trying to connect to a weak WiFi access point on battery power.

And what I have found is:

1. On AC power, the external field DOES make the screen flash. But just once. It then recovers and normal operation continues.
2. On battery power, the external RF field makes the screen flash once, same as on battery power. But it then continues to flash erratically forever even with the external RF field removed.
3. Setting the option "Panel Self Refresh" to DISABLED when on battery power in the Intel HD graphics application prevents the flashing from developing into continuous flashing. It flashes once and then recovers, same as on AC power.

Disabling the option "Panel Self Refresh" would seem to prevent some power savings on battery power. How much is unknown. However, the benefit would seem to outweigh the disadvantage.

Again, this still looks to me to be an RFI issue between the RF field generated by the WiFi card (possibly more intense during an attempted connect to a weak AP) and the graphics adapter or possibly the display itself. If that is true, there is probably NO hardware fix short of redesign since it is caused by an RF sensitivity in the display or graphics adapter in combination with the placement and orientation of the WiFi antennas (in the display itself). It might explain why Lenovo thinks it can be fixed by replacing the LCD and/or the system board. However, if successful those "fixes" would be extremely tentative and the issue would possibly reappear at some later date. Unless there IS a redesigned part they aren't telling me about?

I think I am at the end of the road here. I have a work around with minimal negative impact. But unless I am the ONLY one who has discovered what appears to be the root cause, I am very disappointed in the lack of response by Lenovo. I understand if Lenovo does not actually have a fix. But at least say so? The way it has been left makes it appear as though they A) know what the issue is and B) are ignoring it in the hopes I and others with the same issue will just give up and go away.

Lenovo.... still "over to you".

Paul
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Re: X1C3 display flashes???

#38 Post by pgoelz » Mon May 01, 2017 7:14 am

Further update..... after I was somewhat negative on an unsolicited Lenovo survey, Lenovo reached out and put me in touch with someone slightly higher up. He explained that replacing the LCD and cable might indeed resolve it..... and most importantly made a plausible case for it. While no one at Lenovo has yet indicated that this is a known issue, he did state that if the cable was damaged it could cause the kind of RFI I seem to be seeing since it (assumed) would cause the cable itself to radiate RF. One of the antenna cables passes close to the susceptible spot I discovered in the lower left corner of the display and if the cable itself was radiating, I can see how that could cause issues. No explanation for why the cable would be damaged.

I have sent the machine in for depot service. Lets hope that it comes back cured and that this won't be a big waste of ~1.5 weeks. I guess on the bright side, it might take care of a couple rub marks on the display lid ;)

I have to say, though, that aside from the fact that Lenovo is acting like they have never heard of this issue, they DO seem to want to help and have been pretty responsive.

Paul
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Re: X1C3 display flashes???

#39 Post by pgoelz » Wed May 03, 2017 6:46 pm

OK, the machine is back from depot service (five days door to door including a weekend) with a new mainboard, display cable (they did not replace the display itself as originally proposed) and WiFi card. So far, I have not been able to reproduce the issue either with WiFi connects OR an external RF field so the issue does seem to be resolved. Good on Lenovo!

The only hitch was that the replacement mainboard with its new UUID caused Windows 10 to deactivate. Lenovo said the fix was to revert to Windows 8.1 via the recovery media. I did some reading and it supposedly is easy to transfer the digital license. However, the process failed several times. I finally was asked to switch from a local account to a MS account and it succeeded. I then switched back to a local account and all is well.

Paul
Paul Goelz
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