vladpostolache
Posts: 5
Joined: Fri Nov 27, 2015 10:33 am

Screen flicker with RPi2 and Samsung large TV

Fri Nov 27, 2015 10:53 am

Hi, guys.
I'm basically dead tired on fiddling with this problem. Let me start with the beginning.
I got myself an RPi 2 (the one with the quad-core CPU) for my media center project. As soon as I got it, everything went according to my plan: I loaded up openelec 6.0.0 on an 8 GB SD card (Hama, class 10), I connected the Pi to my Samsung UE65H6400 LED TV, network plugged in and booted it. All was awesome, the OS was running smoothly, I configured my Kodi Isengard how I liked it, with samba shares from my desktop running flawlessly. I also connected to it a wireless Microsoft keyboard and a Trust MCE remote I used with my desktop. Everything is great, I can basically control the Pi with all the remotes on my livingroom table (this was a complete surprise, I didn't know about CEC and it left me speechless for a while, like wtf is happening, how did I do this - awesome stuff).
But a few minutes after booting the Pi, the screen starts to flicker. Every 30-40 seconds, it's like the TV loses the signal and gets it back after 2 seconds. Total blackout for 2 seconds, audio and video. And it gets worse as time goes, 10-15 minutes into the uptime, the blackouts are a few seconds apart. At first, I suspected the power source for the Pi and I switched it with everything around - my smartphone charger, another USB charger and final, a Galaxy Tab 2 charger with confirmed 2A output - the problem is still there. Ok, it must be the HDMI cable, then. I went and got an expensive, gold plated connectors, high speed, ethernet, fancy HDMI cable and I was convinced that would do the trick. Nope. Still flickering.
Then I got into the configuration files. I tried everything I found. hdmi_safe=1, still not working. Boosting the HDMI signal with config_hdmi_boost up to 11, still not working. hdmi_drive, hdmi_group, the hotplug thingy, none is working. Anything I do, the screen flickers unbothered.
The thing is, after a while, I connected the Pi to an older TV I have, also Samsung, but LCD and much smaller, 32”. I haven't had a chance to test a movie file on it (it's far away from the router), but while in the menus, the screen doesn't flicker on this one.

So the question is this: could it be that the TV I'm trying to use the Pi on is too large for the signal strength the Pi is capable of? If you ask me, that would be absurd - the Pi puts out image at the same resolution, it doesn't matter if that image is posted on a 10” screen or a 100” screen, as long as it's the same resolution, right? But then, why isn't it working?

The next thing I think I'll do is to fiddle with the service menu of the TV and see if I can somehow modify the HDMI input parameters, maybe I can find something that helps it hold on to the signal better.

But in the meantime, has anybody else had the problem I'm having?

drgeoff
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Re: Screen flicker with RPi2 and Samsung large TV

Fri Nov 27, 2015 5:58 pm

Physical screen size is indeed irrelevant. However depending on the native resolution of the panels, different TVs may request a different resolution HDMI signal from the RPi. Higher resolution needs a higher bit rate and is therefore more prone to any transmission problems.

Most Samsung TVs have more than one HDMI input. Have you tried another input?

vladpostolache
Posts: 5
Joined: Fri Nov 27, 2015 10:33 am

Re: Screen flicker with RPi2 and Samsung large TV

Fri Nov 27, 2015 6:41 pm

My TV has 6 HDMI inputs, I've tried them all and the same thing happens.
I just figured. This happens only when used with the big screen TV. With the other, smaller TV it doesn't happen. Maybe it's because when I plug it in the power outlet, there are about 10 other devices plugged in near it, in the same wall outlet. Perhaps not enough power reaches the Pi (because of all the other devices sucking energy) and when the power drops, it blacks out. When I tested it with the other TV, there was only the TV and a desktop computer plugged in with the Pi.

I'm not at home, I'll get home and try this a little later. If this is the solution, I'll throw myself out the window.

vladpostolache
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Joined: Fri Nov 27, 2015 10:33 am

Re: Screen flicker with RPi2 and Samsung large TV

Fri Nov 27, 2015 8:58 pm

Nope, still happening.

I plugged it in a wall outlet all by itself and even though it seems it takes longer than before, the blackouts eventually come back. And now I tested it more extensively on the smaller TV and it happens there as well, after some time. The CPU temperature shows around 45 degrees Celsius. How hot do you Pi-s get?

Other than that... I'm baffled. I have no words. I'm dead speechless. It eludes me and I don't have anything else to try.

How probable would it be that my Pi is faulty?

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DougieLawson
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Re: Screen flicker with RPi2 and Samsung large TV

Sat Nov 28, 2015 12:17 am

Have you tried adding

Code: Select all

config_hdmi_boost=4
to your config.txt and rebooting?
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drgeoff
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Re: Screen flicker with RPi2 and Samsung large TV

Sat Nov 28, 2015 11:42 pm

DougieLawson wrote:Have you tried adding

Code: Select all

config_hdmi_boost=4
to your config.txt and rebooting?
Dougie
Time and time again you prove that you don't read posts properly.

The OP wrote:
I tried everything I found. hdmi_safe=1, still not working. Boosting the HDMI signal with config_hdmi_boost up to 11, still not working.

vladpostolache
Posts: 5
Joined: Fri Nov 27, 2015 10:33 am

Re: Screen flicker with RPi2 and Samsung large TV

Wed Dec 02, 2015 12:13 pm

As a matter of fact, yes, I already tried that, as drgeoff pointed out.
After everything I've tried, I concluded that my Pi is faulty and I'm going to get a replacement today. I'll post the results later, if this keeps happening I'm back to square one (and I'm not sure I could take it anymore, from an emotional point of view).

dom
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Re: Screen flicker with RPi2 and Samsung large TV

Wed Dec 02, 2015 12:53 pm

Does the flicker only occur when playing video?
Some suggestions here:
http://kodi.wiki/view/Raspberry_Pi_FAQ# ... ts_on_HDMI

vladpostolache
Posts: 5
Joined: Fri Nov 27, 2015 10:33 am

Re: Screen flicker with RPi2 and Samsung large TV

Wed Dec 02, 2015 10:18 pm

The blackouts were happening all over the interface, not only during playback.
I went to the store and I got it replaced altogether. Turns out it was a faulty unit, because now everything works flawlessly. The guy running the store told me 2 or 3 units returned before with the same symptoms, so it might be that a batch of Pis were contaminated by this problem or it's just a sensitivity of the chipset that shows its ugly head once in a while. But it surprises me as hell that I haven't been able to find anything online on this subject.
Anyway, I got it solved and I'm so relieved that I did.
If anybody else has this problem and nothing seems to solve it, just get it replaced, it might be the Pi's fault.

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Re: Screen flicker with RPi2 and Samsung large TV

Sat Dec 05, 2015 9:51 am

vladpostolache wrote:The CPU temperature shows around 45 degrees Celsius. How hot do you Pi-s get?
My Pi's (B+) average temperature is 41 (EDIT: 41-44) Celsius when I'm using it for web browsing and other average stuff. When it's just booted it's usually 36-40 degrees, but sometimes can be as low as 26 degrees. The temperature quickly climbs up to average though. The highest temperature I've ever seen is around 49 degrees. I use Raspbian, and have a PiBow case.
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vijayor
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Re: Screen flicker with RPi2 and Samsung large TV

Mon Jan 30, 2017 5:42 am

In case some one else came looking for a similar problem with their RPI, here is my story:
Using RPI 3 with LG 49 Inch UHD TV, Raspbian default theme was working fine but with pixel desktop screen use to flicker, turn off and resume approximately every 4 seconds.

Checked and edited, tested various combinations of settings at /boot/config.txt but nothing would make any difference.

Finally changing the HDMI cable solved the issue, not sure what exact technical aspects influenced this but could be that i had a older cable and didn't support the necessary bandwidth for resolution + refresh rates.

sojeshj
Posts: 1
Joined: Tue Mar 28, 2017 4:44 am

Re: Screen flicker with RPi2 and Samsung large TV

Tue Mar 28, 2017 4:47 am

I am using RPi3 and for the last 3 months all were fine. Today it started flickering. I was always using Dell monitor and it started flickering today. So, I am wondering if it's any recent updates which started this problem.

I am not sure if it was recently updated...

drgeoff
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Joined: Wed Jan 25, 2012 6:39 pm

Re: Screen flicker with RPi2 and Samsung large TV

Tue Mar 28, 2017 9:14 am

Connect your Dell monitor to another piece of equipment to check the monitor. Failing capacitors in monitor power supplies can give those symptoms.

Not saying that is definitely your problem. Just check the monitor in case you'll be trying to fix a RPi which isn't broken.

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RaTTuS
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Re: Screen flicker with RPi2 and Samsung large TV

Tue Mar 28, 2017 9:20 am

try another HDMI lead
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santhiya1702
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Re: Screen flicker with RPi2 and Samsung large TV

Thu Aug 30, 2018 10:40 pm

1. sudo nano /boot/config.txt

2. Add the below line in config.txt
dtparam=audio=on

Save config.txt
3. sudo reboot

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