28" 4K UHD monitor B286HK - I'm having a problem with back light issue

unsigned
unsigned Member Posts: 6 New User
edited March 2023 in Monitors
Monitor back-light.jpg

I'm having a problem with what I believe is a back light problem - brights in some parts, and dim in others (when cold).

The monitor seems to work fine after a long warm-up and power cycle. When I shut-off my computer at night and come back the next day I see the problem as shown in the image.

A picture is worth a thousand words. Has anyone ever seen this before. ANY IDEAS ?

[Edited the thread to add issue detail]


Answers

  • JackE
    JackE ACE Posts: 44,893 Trailblazer

    »»work fine after a long warm-up»>Has anyone ever seen this before. »>

    Sure. I have a different 28 and 32 inchers that each take ~5 minutes to settle down. The image you posted looks more like initial backlight bleeding. So how long is your's taking? If possible, please post full screen phone photos of plain red.jpg, green.jpg, blue.jpg, black.jpg & white.jpg files.

    Jack E/NJ

  • unsigned
    unsigned Member Posts: 6 New User

    I have had this monitor for at least 4-5 years with outstanding color/performance & never had a problem. Only recently did I see this behavior. It seems to work fine (normal full intensity) the rest of the day if I toggle the power a couple of times after about 15 min. It was so annoying that I have since gone to an LG 32" Class 4K UHD FreeSync Monitor (Model  32UK50T-W). But I would still like to fix this to have a 3rd monitor.

    Can you suggest a website where I can find those color JPG's all in one place. I don't seem to find one's that fill-up the entire screen.



  • JackE
    JackE ACE Posts: 44,893 Trailblazer
    edited March 2023

    »»Only recently did I see this behavior.»>

    Suddenly? Or gradually? This often happens with LCD TVs & monitors primarily due to BIOS chip degradation. Just keeps getting worse over time.Till you either keep it in standby mode all the time so it stays up, or simply replace it. This is a Win8x era monitor. You might try to re-install the driver in Win10's or Win11's Win7/Win8x compatiblity mode if you're not using Win7 or Win8x anymore. Download is at this link.

    https://www.acer.com/us-en/support?search=B286HK&filter=global_download&suggest=b286;0

    As for the jpg files, simply google or google image search , for example ‘blue.jpg". They should pop right up. Pick a navy blue,jpg. A medium green,jpg. etc. Don't worry too much about shades. I’d like to see what they look like before the monitor warms up.

    Jack E/NJ

  • unsigned
    unsigned Member Posts: 6 New User
    white.jpg
    red.jpg
    green.jpg
    blue.jpg

    Here you go. The black was horrible due to reflection of objects facing the monitor so I did not post it.

  • JackE
    JackE ACE Posts: 44,893 Trailblazer

    »>It seems to work fine (normal
    full intensity) the rest of the day if I toggle the power a couple of
    times after about 15 min.»>

    1. Has the 15min warmup period been constant since this startued happening? Or does it seem to be getting longer or warmup time unpredicatble?
    2. Do you always have to toggle it off and on after the warmup period?

    )

    Jack E/NJ

  • unsigned
    unsigned Member Posts: 6 New User

    The warm-up time seemed to be getting longer. Note that I always let the monitor go to sleep/standby even though I completely shut-down the computer. I have to toggle the switch on/off after the warm-up period to clear the problem.

    It does not return to normal by itself, but once it returns to normal, it's fine for 14-15 hrs. straight until I start over the next morning.

  • JackE
    JackE ACE Posts: 44,893 Trailblazer

    »»The warm-up time seemed to be getting longer.»>

    If you're lucky, the LCD video ribbon cable connectors at the mainboard & screen backlight inverter simply need to be re-seated a few times to help clean up (corrosion) the contacts. As things warm up & expand, they're probably making better contact. It'll likely get progressively worse until you bite the bullet, open it up and re-seat the connectors. Unfortunately, this is not a pleasant task. Sorry, there seems to be no software solution to this issue.

    Jack E/NJ

  • unsigned
    unsigned Member Posts: 6 New User

    Looking at the back of the monitor there are no screws. I can see the seam between the front panel and the back cover. It just looks like the back panel is compression seated to the front. I'm not averse to opening it up considering that the other option is just to throw it away. I have searched and find only a user manual, but no service manual. Do you know of a source for the service manual for the model B286HK ?

  • JackE
    JackE ACE Posts: 44,893 Trailblazer
    edited March 2023

    Remove all accessible screws around perimeter. Then remove the stand as per the image below. Then remove 4 more screws behind the stand attacment point. Then use a credit card or wedge to pry the back off the screen. You'll probably break a bunch of plastic latches in the process. Then lift the back cover and unplug the screen connector. You might have to remove tape on other wires to lift the back cover. And you might have to remove 8 screws from the mainboard to access the screen's mainboard connector. Try to avoid it if possible because it's a mess of wires and ribbon cables on the other side of the mainboard with high risk of collateral damage.

    b2stand.jpg

    b2mb.jpg

    Jack E/NJ

  • unsigned
    unsigned Member Posts: 6 New User

    Hello - Thanks for the detailed pictures.

    Do you happen to know the part number for the backlight that the ribbon cable connects to, and where to obtain it? I'm a ham radio operator for 40+ years and have worked on many transceivers & computers and have done a lot of disassembly of printed circuit, logic and RF boards over the years to effect component replacement. It stikes me as kind of odd to think that there would be active corrosion on contacts used on indoor electronics for a device that is less than 10 years old. The indoor environment for a computer and monitor is significantly less harsh than that of (for example) automotive connector contacts under the hood of my car. Ultimately the corrosion risk from environmental exposure in a very dry indoor environment is extremely low when compared against the potential of component failure over time. Ultimately, it would seem that component failure is a more likely cause of this problem. To be sure, there are limited instances where “exercising” a connector can restore working order to a component to restore service - I used to work for a global telco, so I have occasionally seen this work in practice - but the general approach to this is that “hope is not a strategy”.

    If what looks to be the backlight (that connects to the ribbon cable) is not something that would be available for purchase, then this is likely going to be a lost cause. Ultimately I would feel better in knowing the availability of the part up-front. Also, what I don't see in the pictures is how the block of three boards attaches to the back of the inside of the screen - it looks to be taped at the corners (no screw or attachment points in the picture). If I have to take this all apart only to suspect compoent failure then I may need to put it all back together to wait for a part (that I may not be able to get). So the question is whether the part number is known and whether it is available. I can give the serial number to determine the answer.

  • JackE
    JackE ACE Posts: 44,893 Trailblazer

    »»>I'm a ham radio operator for 40+ years and have worked on many
    transceivers & computers and have done a lot of disassembly of
    printed circuit, logic and RF boards over the years to effect component
    replacement. It stikes me as kind of odd to think that there would be
    active corrosion on contacts used on indoor electronics for a device
    that is less than 10 years old. The indoor environment for a computer
    and monitor is significantly less harsh than that of (for example)
    automotive connector contacts under the hood of my car.

    Heh-heh. Problem with today's new-fangled consumer laptop, desktop & monitor mainboard/chips are µV & pA level control power going thru super-thin gold-plated contacts on the connectors. Computationally speaking, they are considerably more powerful but much more cheaply made and fragile than the embedded computers (with more soldered connections) in most transceivers (except maybe Baofengs 🙂 ) , automobiles, trains, holter monitors, smartphones & other devices where issues like this might have much more serious consequences.

    At any rate, the screen's LED backlight itself is of course integrated with the screen. Its controller or inverter may or may not be integrated. Not clear from the specsheets available to us Acer users. Most likely on the mainboarboard itself. Accordingly, If re-seating all the connectors to the screen & boards fails to correct the issue, then there's not much else you can do except replace the screen (part no. KL.2800N.002) or the mainboard (55.T1JM2.002), neither of which sound too practtical.

    Sorry

    KC2HSX

    Jack E/NJ

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