LG C9 auto dim issue

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Paul Mohr

Audioholic Intern
I recently purchased a LG C9 Oled tv to replace my old Sharp LED tv. I use the tv for movies, tv and it doubles as my computer monitor. It is having a weird issue with auto dimming technology built into it. When I use it to view web pages the screen goes dim, then gets bright again, then dim again and back and forth. It is actually doing this right now as I type this lol. I understand this is a protection feature of the tv to help prevent burn in and I get why they did it. However I don't like it and it doesn't play nice with web pages, youtube or my desktop. HOLY crap it just ramped up again and blinded me lol. Does anyone know if there is way to turn off this feature? I would really like the backlight or whatever it its called on an oled tv to stay where I chose to set it. I know the brightness level I like and don't want the tv making this choice for me at random. I have a harmony remote so I can get into the service menu and instart menu if that helps. I just don't know what I am looking for and don't want screw something up in there.

I called LG and they told me a bunch of stuff to try, like turning off all the auto settings and true motion and all that. Which were all off already. They gave me a list of stuff to try and said to call back if it still did it. I tried them, none of them worked. Which I really didn't think they would honestly. So I called back today and tried to explain exactly what was happening. She had me do the picture test thing, which worked like it is supposed to. She told me my tv was broke and I needed to get it serviced lol. I told her I don't think it is broke. I think it is doing exactly what is supposed to do. I just want to know if I can shut that feature off. I asked to talk to a technician and she wouldn't let me. She said she did already and he said the tv is broke. I finally got her to agree to have a technician call me back and talk with me. I am not holding my breath though.

So if anyone has any ideas I would love to hear them. And if someone does call me back I will come back and let you all know what they said in case someone else has this issue. Other than the tv works great, I love it. It just doesn't make a very good computer monitor so far. I do understand that is not what it was designed to do though so I am not going to throw a fit about it.
 
TLS Guy

TLS Guy

Audioholic Slumlord
I recently purchased a LG C9 Oled tv to replace my old Sharp LED tv. I use the tv for movies, tv and it doubles as my computer monitor. It is having a weird issue with auto dimming technology built into it. When I use it to view web pages the screen goes dim, then gets bright again, then dim again and back and forth. It is actually doing this right now as I type this lol. I understand this is a protection feature of the tv to help prevent burn in and I get why they did it. However I don't like it and it doesn't play nice with web pages, youtube or my desktop. HOLY crap it just ramped up again and blinded me lol. Does anyone know if there is way to turn off this feature? I would really like the backlight or whatever it its called on an oled tv to stay where I chose to set it. I know the brightness level I like and don't want the tv making this choice for me at random. I have a harmony remote so I can get into the service menu and instart menu if that helps. I just don't know what I am looking for and don't want screw something up in there.

I called LG and they told me a bunch of stuff to try, like turning off all the auto settings and true motion and all that. Which were all off already. They gave me a list of stuff to try and said to call back if it still did it. I tried them, none of them worked. Which I really didn't think they would honestly. So I called back today and tried to explain exactly what was happening. She had me do the picture test thing, which worked like it is supposed to. She told me my tv was broke and I needed to get it serviced lol. I told her I don't think it is broke. I think it is doing exactly what is supposed to do. I just want to know if I can shut that feature off. I asked to talk to a technician and she wouldn't let me. She said she did already and he said the tv is broke. I finally got her to agree to have a technician call me back and talk with me. I am not holding my breath though.

So if anyone has any ideas I would love to hear them. And if someone does call me back I will come back and let you all know what they said in case someone else has this issue. Other than the tv works great, I love it. It just doesn't make a very good computer monitor so far. I do understand that is not what it was designed to do though so I am not going to throw a fit about it.
I have a C9 OLED and I have never had that problem ever. It works fine from my 4K HTPC. There is no problem with web pages. I have no idea what your problem is, but your TV either has a problem or there is a problem with your computer settings. I have been really happy with my 77" OLED TV.

I use this TV with Amazon and Netflix apps with audio return, I have Comcast box, two BD players and a universal DVD player, ChromeCast Ultra and my 4K HTPC and have not had an issue like you describe with any of these sources. The TV is driven via a Marantz 4K pre/pro and the streaming Netflix and Amazon apps via Ethernet hardwire.

Since you only have trouble with the web pages, I suspect that the trouble is from your computer.

I will say I had problems with a 2K Oppo BD player. So I think this TV can have a problem with older units. I had to retire that unit to another system. So may be you need a 4K computer.

What you could do is get a ChromeCast Ultra and bring up web pages from an iPhone or iPad and see if you still have the problem. If that works OK, you probably need to rebuild your computer. I'm not sure you can buy one off the shelf. Mine is an in house build.
 
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Paul Mohr

Audioholic Intern
Thanks for the response. It works fine for any video source, even on the computer. It is just with with static images like web pages or the desktop if it sits for a while. I assume it is going dim in order to save the screen. I read somewhere that they will do that. Maybe it has something to do with the logo setting? I haven't tried that yet. Its not my computer because it never did it with my sharp LED I used before. My computer doesn't have adaptive brightness or anything like that. That is the first thing I checked. I hope my tv isn't defective, that will be a huge pain in the butt in this new age. Honestly, it is something I can live with if I have to, it is just annoying.

I did find a setting in the instart menu that said "dimming". I turned it to off and it solve the problem. The down side is it defaulted to max brightness and you couldn't adjust through the menu any more lol. I put it back to on and stopped fiddling with that menu until I could talk to someone with some knowledge about it. And the tech from LG did NOT call me back.

While your feedback is not what I wanted to hear, I am glad you told me and thank you. Maybe it does have an issue. I am hoping to find someone that calibrates them and has a good idea how they work. I might call a local custom home theater installer and see if they know anything about it if it comes to that.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Thanks for the response. It works fine for any video source, even on the computer. It is just with with static images like web pages or the desktop if it sits for a while. I assume it is going dim in order to save the screen. I read somewhere that they will do that. Maybe it has something to do with the logo setting? I haven't tried that yet. Its not my computer because it never did it with my sharp LED I used before. My computer doesn't have adaptive brightness or anything like that. That is the first thing I checked. I hope my tv isn't defective, that will be a huge pain in the butt in this new age. Honestly, it is something I can live with if I have to, it is just annoying.

I did find a setting in the instart menu that said "dimming". I turned it to off and it solve the problem. The down side is it defaulted to max brightness and you couldn't adjust through the menu any more lol. I put it back to on and stopped fiddling with that menu until I could talk to someone with some knowledge about it. And the tech from LG did NOT call me back.

While your feedback is not what I wanted to hear, I am glad you told me and thank you. Maybe it does have an issue. I am hoping to find someone that calibrates them and has a good idea how they work. I might call a local custom home theater installer and see if they know anything about it if it comes to that.
I do think that you should try the Comcast trick I suggested. That will tell you if your TV is OK. I have to think that your computer settings are not correct for that TV.

What are you connecting your computer to? Do you have a receiver or pre/pro? Generally there is a receiver or something of that nature in the chain. Generally it is peripherals connected to a receiver or pre/pro, and the apps sending the audio back to that device through audio return.
 
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Paul Mohr

Audioholic Intern
My computer does run through my AV receiver, a denon. LG suggested I bypass it and run it directly into the tv, which I tried. It didn't change anything. And my computer is new, I just built it a few months ago. Ryzen 3600, new motherboard and a new nvidia 2070 video card. On the latest windows 10 build. Desktops don't normally have adaptive brightness, it is mostly a laptop thing. I double checked mine and it doesn't. I think I saw the tv has a browser built into it, maybe I can try that and see what happens? I noticed it does the same thing with netflix too. If I pause a video after a while the screen will dim on the paused image. Once you start playing it again it gradually gets brighter again over a few seconds.

I turned off the logo dimming feature and it got better. It still does it but it isn't so aggressive anymore. I really don't think these tv's were built to be computer monitors. It might be messed up, or it might just be something I have to live with I guess. Maybe that tech will call me tomorrow and give me some more insight. If its messed up I am not sure how I am going to deal with that. I can hardly move the thing on my own let alone get it off the mounts, get it down the steps and ship it somewhere lol. And if I have to pay for it that sure isn't happening. I will get someone to help me and take it back to best buy and swap it for a LED tv I can afford. Which is too bad, other than this I really like the tv.
 
TLS Guy

TLS Guy

Audioholic Slumlord
My computer does run through my AV receiver, a denon. LG suggested I bypass it and run it directly into the tv, which I tried. It didn't change anything. And my computer is new, I just built it a few months ago. Ryzen 3600, new motherboard and a new nvidia 2070 video card. On the latest windows 10 build. Desktops don't normally have adaptive brightness, it is mostly a laptop thing. I double checked mine and it doesn't. I think I saw the tv has a browser built into it, maybe I can try that and see what happens? I noticed it does the same thing with netflix too. If I pause a video after a while the screen will dim on the paused image. Once you start playing it again it gradually gets brighter again over a few seconds.

I turned off the logo dimming feature and it got better. It still does it but it isn't so aggressive anymore. I really don't think these tv's were built to be computer monitors. It might be messed up, or it might just be something I have to live with I guess. Maybe that tech will call me tomorrow and give me some more insight. If its messed up I am not sure how I am going to deal with that. I can hardly move the thing on my own let alone get it off the mounts, get it down the steps and ship it somewhere lol. And if I have to pay for it that sure isn't happening. I will get someone to help me and take it back to best buy and swap it for a LED tv I can afford. Which is too bad, other than this I really like the tv.
Well, I just brought up a bunch of web pages, and the TV behaved like a really good computer monitor, for my HTPC.

How long is your HDMI cable? I wonder if it is too long and you are on the verge of signal loss, which the static image reveals. These TVs I know need a really good HDMI connection. I'm using a Ruipro hybrid cable, with voltage inserter. That is to say the picture is transmitted optically and the audio via copper. The voltage inserter is driving the converters and not the HDMI port on the pre/pro. I did confirm that a standard cable in this room did not work.

Try and work this out. These are easily the best TVs available currently.
 
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Paul Mohr

Audioholic Intern
The HDMI cable is a great tip, I will check that out. It isn't the greatest cable and it kind of long. I have also had issues in the past with my other tv losing the signal on occasion if the cable got bumped or something. It might be junk and was kind of suspect to begin with but I forgot all about it.

You also mentioned 4K. I switched my computers resolution to 4K instead of 1080p and it hasn't done it since then. But then I have only been on it for a few minutes and it is kind of random thing. It isn't something I can force. OK, scrub that, it just did it lmao. Had my hopes up for a few minutes there darn it. I will for sure swap out some cables tomorrow and test that.

I tried the built in browser and you really can't make it do it. If you leave it sit too long it just goes into screen saver mode. Hopefully I will get lucky and figure something out.
 
TLS Guy

TLS Guy

Audioholic Slumlord
The HDMI cable is a great tip, I will check that out. It isn't the greatest cable and it kind of long. I have also had issues in the past with my other tv losing the signal on occasion if the cable got bumped or something. It might be junk and was kind of suspect to begin with but I forgot all about it.

You also mentioned 4K. I switched my computers resolution to 4K instead of 1080p and it hasn't done it since then. But then I have only been on it for a few minutes and it is kind of random thing. It isn't something I can force. OK, scrub that, it just did it lmao. Had my hopes up for a few minutes there darn it. I will for sure swap out some cables tomorrow and test that.

I tried the built in browser and you really can't make it do it. If you leave it sit too long it just goes into screen saver mode. Hopefully I will get lucky and figure something out.
12 ft is about the limit for a passive HDMI cable. I strongly recommend the Ruipro hybrid cables with a voltage inserter to power it.

4K is much more fickle.

I was thinking last night that your problem could be a ground loop. I did my set up last October. The HTPC was an in house build. Initially I had strange trouble, like noise moving the mouse and jittery picture quite bit, and I think I may have had your problem. When I investigated I found that the power supply, a home brand of Micro Center, had an internal ground loop. So I thew it back at them and bought a very high end power supply, and that was the end of the troubles.

Now my TV is supplied from the UPS in my first AV rack. So the TV is grounded right back to that rack and the robust studio ground plane. I really engineer my installations carefully and robustly. Anyhow your trouble could be a ground loop between your TVg round and your computer ground. Ground loops in computers manifest themselves in very strange ways, and not just the usual hum and buzzes.

Did you build your computer, or was it "off the shelf" so to speak? Computers for AV use have to be built to a very high standard and carefully thought out. That is why my HTPC and DAW are very robust home builds.

Thinking about your problem I suspect a cable and or grounding issue. I suspect your TV is fine, but there are issues related to what I have pointed out. It takes very little to cause really annoying problems. That means robust engineering and sourcing the highest quality components.
 
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Paul Mohr

Audioholic Intern
Ok after doing some research and fiddling about I got it figured out. The TV isn't defective and it isn't my computer, cables or anything else. It is normal operation for this tv due to ABL and ASBL and some firmware change they made to their OLED tvs sometime in 2018. Some people seem to have more of an issue with than others but it isn't a defect. There was even a petition to LG trying to get them to give owners the option of turning it on or off.

I turned off logo luminance and disabled TPC through the instart menu and it is much better now. It didn't completely go away but you can barely tell it does it now. Instead of dropping all the way down and ramping back up again in steps it is just like a small pulse now. And it only changes a few steps. You kind of have to look for it to see it.

I am just glad it wasn't broken. I was starting to get worried it had some kind voltage issue and couldn't hold the brightness.
 

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