Author Topic: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!  (Read 4268 times)

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Offline wraper

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #25 on: July 23, 2018, 09:11:08 am »
What's worse is if you turn off a monitor, it causes Windows to go haywire and shuffle all our applications all over the place.
That's certainly displayport connection, HDMI interface does not care if monitor is ON/OFF. Did you try to change the cable? There are a hell of a lot DP cables in the wild which don't follow the standard. Including backfeeding power from monitor to GPU.
 

Offline BrianHG

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #26 on: July 23, 2018, 10:32:06 am »
HDMI interface does not care if monitor is ON/OFF. Did you try to change the cable? There are a hell of a lot DP cables in the wild which don't follow the standard. Including backfeeding power from monitor to GPU.

Yes HDMI does.  It's a feature of some monitors and video projectors to hold the monitor ID and state even when the power is cut off.  In my video scaler, I had specific circuitry on my HDMI and DVI inputs to retain this feature.

Example, my BenQ TH670 , when powered down, my laptop doesn't care and thinks it's still connected and at 1080p, even if I remove the projector's 120v power chord.  As long as I don't remove the HDMI cable, it retains the video mode and setup.  With my stupid newer BenQ and Optoma HD142X, just turning off it's power on the remote control F--KS everything up.  (Why is everything getting so cheap and short sighted today... The manufacturers claim it is a feature when the engineering knows you save around 50 to 90 cents by not having the feature...  Even my 4 year old BenQs didn't mess up windows when I turned them off...) Thankfully, I can plug my laptop into my video scaler, then into these garbage newer cheaper crappy junk to fix that problem.  There also exists external DVI/HDMI EDID clone/bypass boxes which offer the same feature.  They also might exist for display port as well.


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Offline EEVblog

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #27 on: July 23, 2018, 11:21:28 am »
Cable changed to what looks like a really good quality one, now it's just turning off without me moving. Maybe David moving behind the monitor, I don't really know.
 
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Offline wraper

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #28 on: July 23, 2018, 11:47:37 am »
Cable changed to what looks like a really good quality one, now it's just turning off without me moving. Maybe David moving behind the monitor, I don't really know.
Is it HDMI or DP? I've seen like a dozen of Raspberry Pi with one half of HDMI differential transmitter been blown almost short to GND but monitor still displaying image most of the time. Although in such case it likely won't work at all @ 4k.
« Last Edit: July 23, 2018, 11:50:29 am by wraper »
 

Offline Brumby

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #29 on: July 23, 2018, 11:49:07 am »
Maybe our HDMI cables need a tinfoil hat...

I have a couple of soldering stations and power supplies in a small wooden shelf unit I made which sits about 2" to the right of my rightmost monitor.  One of the soldering stations has the main power switch at the back which means it is always switched on - but I have the whole group of devices on a master power switch.

Sometimes when I switch on this master switch nothing happens to the neighbouring monitor.  Sometimes I get a fleeting black line and sometimes the whole screen goes black for a couple of seconds.  My left monitor has never skipped a beat.
« Last Edit: July 23, 2018, 11:54:27 am by Brumby »
 

Offline BrianHG

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #30 on: July 23, 2018, 12:07:17 pm »
Cable changed to what looks like a really good quality one, now it's just turning off without me moving. Maybe David moving behind the monitor, I don't really know.
@Dave, first try a lower res video mode if allowed, then try a different PC or video card.  Something sound just too flaky.  Note that inside some monitors, the video input connector is on a daughter board, then with a cheap ribbon cable, or even cheap single stranded wires, the video is fed to the monitor's main PCB.  This is a weak point where a flaky wiring or bend in the wiring in the case of the stranded wiring type sometimes leads to a semi-lemon monitor video input.  Try using the monitor's alternate video input.  If this makes no difference, then it is most likely not a problem with the monitor itself.  Also make sure your HDMI cable is truly 4K PC RGB 4:4:4 compliant and not one of those crummy lower bandwidth cables which work at 4K in home theater setups where the run the color in a lower bandwidth 4:2:2 mode.  I've gotten this type of shaft before, those HDMI cable just don't work at all on a PC.

« Last Edit: July 23, 2018, 12:09:04 pm by BrianHG »
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Offline Red Squirrel

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #31 on: July 23, 2018, 12:11:40 pm »
What's worse is if you turn off a monitor, it causes Windows to go haywire and shuffle all our applications all over the place.
That's certainly displayport connection, HDMI interface does not care if monitor is ON/OFF. Did you try to change the cable? There are a hell of a lot DP cables in the wild which don't follow the standard. Including backfeeding power from monitor to GPU.

Interesting, yes I believe they are mostly DP.  Is there a way to disable this "feature" without a new cable?  Or is there something to look for if buying a new cable?  I don't imagine this is something specific they would advertise so don't want to keep buying cables just to try.   

Also this flicker issue for us at work persists even with different cable.  Pretty much everything has changed at some point or the other including the monitors themselves. It's really weird.   The ferrite rings seem to have helped in Dave's video though... it may not have fixed it completely but seems it was not happening as much.  I may get some and give them a shot at work.
 

Offline wraper

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #32 on: July 23, 2018, 12:23:23 pm »
Is there a way to disable this "feature" without a new cable?  Or is there something to look for if buying a new cable?
Nope, you won't be able to disable it even by changing DP cable. You certainly should avoid cheap ebay cables, they are really dodgy. Change to HDMI if possible.
 

Offline SparkyFX

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #33 on: July 24, 2018, 06:01:11 am »
Cable changed to what looks like a really good quality one, now it's just turning off without me moving. Maybe David moving behind the monitor, I don't really know.
What an improvement ;-)

I had similar issues with a lightning protection in a power strip being triggered by ESD, caused by movement of the office chair on a plastic mat and rolling toward the table. I grounded the table (a metal part of it) to ground on the power strip and the issue was gone. At least the discharge seems to take a different path then.

Maybe a wiper contact to ground on the chair helps as well :-) Similar to what was used on cars for years, where i also had issues with getting a discharge when leaving the vehicle and touching the frame, depending on clothes and shoes.

Is it a monitor with a power brick or with mains connection?
 

Offline BrianHG

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #34 on: July 24, 2018, 06:23:48 am »
How are the AC power chords wired up in you office setup?  Here in Canada, at my old house, I once used separate wall outlets and I could hear interference from static on my audio amp & occasionally get noise on my analog screens until I powered all my devices from 1 power bar.  It was not that the power bar had any filtering, it was that the GND pin on the wall outlets had separate wiring to the fuse box and the huge GND loop between the fuse box, through 2 floors of the house and the PC, then back and around again for the power chord of the monitor and speaker amp which was on a separate outlet made a gigantic loop antenna for the frame grounds and the signal video and sound cable frame ground connections and the inner cable signal grounds.  Powering everything from 1 power bar at 1 outlet shrunk the loop ground from circling the house 2 times to the length of the power cables for the PC and monitor / audio amp.  This solved a few issues.
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Offline T3sl4co1l

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #35 on: July 24, 2018, 06:47:03 am »
How are the AC power chords wired up in you office setup?

Major fifths, I would assume.

/rimshot

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Offline SparkyFX

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #36 on: July 27, 2018, 01:06:52 am »
It is an annoying problem (at least it distracts), but as long as it recovers there might be no real warranty issue for a manufacturer. One could always claim that it just takes an even larger ESD impulse to trigger problems and it is out of their control what type and size of an impulse occurs (shitstorm effects left aside). The Van de Graff generator approach is cool, but kind of implies that it is usually best to solve the issue at the source, which might be too hard for most consumers - those that recognize it as an effect of ESD kind of know what can be done or who to ask, those that don´t have a problem.

Or am i totally off and there is a standard for ESD-proofing of consumer electronics?

I mean there are several ways to harden a system, from wrapping tin foil around suspect pickup points, conductive paint in housings to other methods of grounding and shielding. Might be worth a video?
 

Offline BrianHG

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #37 on: July 28, 2018, 02:20:50 am »
I am still surprised this is actually a problem.  HDMI should have a separate shield frame ground from PC, PC chassis, PC video card to monitor and such an expensive monitor should have shielded electronics.

I can only guess an opening in the path here is that Dave has a vanity computer case with a plastic/glass closure door where this Faraday cage frame-ground shield is broken because of that huge transparent window.

(I still don't know how those cases pass FCC...)
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Offline SparkyFX

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #38 on: July 28, 2018, 11:26:47 am »
(I still don't know how those cases pass FCC...)
Don´t they just check for emissions of a device, not for the device´s sensitivity?
They might even test in completely different conditions with grounded environment to exclude the person that performs the test from the measurement.
 

Offline T3sl4co1l

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #39 on: July 28, 2018, 11:38:51 am »
(I still don't know how those cases pass FCC...)
Don´t they just check for emissions of a device, not for the device´s sensitivity?
They might even test in completely different conditions with grounded environment to exclude the person that performs the test from the measurement.

Correct, FCC does not require surge or susceptibility (they recommend it, but, alas, that's non-binding).

Most companies making dual-market products will do FCC and CE at the same time, on the same product.  CE is comprehensive, so if you're passing that, you're bound to be pretty well off even in the US.

It's nice that non-binding, foreign regulations sometimes make our lives/products better.

Note that "most companies" means a lot of small and medium quantity manufacturers.  The few big boys, are more than happy to grind out a few more cents by differentiating EMC across markets.  So, say, Sony or Panasonic and such, might make a consumer TV or camera or whatever, that varies worldwide, and are marked for certification accordingly.

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Offline BrianHG

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #40 on: July 28, 2018, 12:26:17 pm »
(I still don't know how those cases pass FCC...)
Don´t they just check for emissions of a device, not for the device´s sensitivity?
They might even test in completely different conditions with grounded environment to exclude the person that performs the test from the measurement.
I meant the other way around.  That big glass window open to all those GHz signals on the traces and connectors of the PCBs leaking out.
Note I see how you thought that my (...) was describing external interference getting in, it's the reason why I placed that quote in brackets...
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Offline EEVblog

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #41 on: July 28, 2018, 01:07:43 pm »
Update: I got a Display Port cable and this seems to have fixed the problem.
 

Offline SparkyFX

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Re: EEVblog #1107 - Shocking 4K BENQ Monitor Problem!
« Reply #42 on: July 28, 2018, 10:19:31 pm »
I meant the other way around.  That big glass window open to all those GHz signals on the traces and connectors of the PCBs leaking out.
Note I see how you thought that my (...) was describing external interference getting in, it's the reason why I placed that quote in brackets...
Nevermind, i just recognized that i made a mistake :-), i translated/interpreted "cases" not as computer case, but as the case of ESD susceptibility of the monitor. Makes a lot more sense now.

Leads to questions of how narrow a faraday cage spacing needs to be for what signal. I think there is more focus on aspects like where the mains are connected and how well the conductive parts of the case are isolated from them and how they are grounded.

E.g. some welders tend to point out that CE style machines have the on/off switch on the back instead of the front (which is less practical), whereas this is not the case with american machines.
 


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