HANNSG HG281D problem with pix and backlights

[budm]

Just fixed this model, the symptom is, at low resolution, the backlights will be on but I can noise and horizontal noise bar, when I set the resolution to its native resolution, it will act like 2-second to black, the blue power light will stay on.

The cause of the problem was due to two bad DC filter caps (100uF 16V) for the 3.3V and the 1.8V LDO on the logic board.
See pictures.
One cap show 80uF with 3 Ohms ESR, another one read 100uF with 3 Ohms ESR.

[tibimakai]

Re: HANNSG HG281D problem with pix and backlights

Great job.

[budm]

Re: HANNSG HG281D problem with pix and backlights

By the way, at first I thought the 3.3 and the 1.8 regulator were bad because the out put were more than 3% less than it should be, so I use the scope to see how bad AC ripples were, and they were high, around 150mV, so I just parallel the caps with another caps, then the output voltages went back to where they should be, 1.8 & 3.3V.
So sometime you do need to use the scope or just parallel the filter caps with good know caps to see if it solves the problem, parallel is so much easier for DIY, I use the scope to find out what is going on.

[momaka]

Re: HANNSG HG281D problem with pix and backlights

So sometime you do need to use the scope or just parallel the filter caps with good know caps to see if it solves the problem, parallel is so much easier for DIY, I use the scope to find out what is going on.

Or if you don't have the expensive equipment or knowledge to use it, when you see electrolytic caps (especially ones from a crappy or not well-known brand) next to hot linear regulators, always try replacing those/adding new ones in parallel before suspecting the regulator.

Congrats on the fix by the way .

[Duncanbest]

Re: HANNSG HG281D problem with pix and backlights

Parallel the filter caps ---->Good debug technique ,thanks for sharing

[abeeftec]

Re: HANNSG HG281D problem with pix and backlights

I cant make a new thread so I figured I would post my listing description and see if someone can tell me what Capacitors I need and point me in a direction where there is a tutorial on how to do this....Thanks....

MY LISTING ON EBAY SAYS......

"YES It does turn on and Works however....
Turns on and runs perfectly beautiful without flaw for about 45 Minutes or sometimes longer
Then it may or may not get NOISE(small vibrating dots) in the picture. Light Blues seem to be what it has the most issues with after it heats up for approx. 45 min's and that depends on differing factors.
Occasionally it doesn't have any issues at all. Just last night my brother used it to game with and it worked perfectly for 5 hours of gaming and never had an issue the entire night.
There are also times when the monitor takes a while to turn on after you hit the power button(3 seconds and sometimes up to 30 seconds) and sometimes you have to pull the HDMI cord and plug it back in to get it to come back on faster. Sometimes
When you hit the power button you have to hit it a few times to get it to come on and this is why I believe it is a Power Supply problem that is causes all the issues.
But I could be mistaken as I don't know everything about LCD's.

Once it heats up it gets these dots all over the place shimmering. It is easier to see with Light blues. They are random it seems and follow cloud images and other images on the screen. But not totally. the shimmering light dots follow the images more so than everywhere else but they are still in other places.. THis is hard to describe of course.

Also, it throws a code too(cant remember what the code is)

But the Brightness control doesn't work correctly either.

It has a bunch of issues. I am thinking maybe it is many caps that have gone bad.

Can someone help me fix all the bad caps and point me in a direction to purchase good caps for this monitor please?

Thanks

[momaka]

Re: HANNSG HG281D problem with pix and backlights

Can someone help me fix all the bad caps and point me in a direction to purchase good caps for this monitor please?

We have a big thread that probably lists every problem (from various people) that this monitor has had. It can be found here:
https://www.badcaps.net/forum/showth...ghlight=HG281D
Yes, I know it IS very long, but definitely worth reading (at least the first several pages).

Judging from your issues, you plobably need to replace the caps on the logic board. Post pictures (either here or on the other thread) and you should find plenty of help.

[abeeftec]

Re: HANNSG HG281D problem with pix and backlights

I will post pictures here.

I posted another post before I saw this response.

I noticed it seemed this was an old thread so I thought no one saw it.

I took the thing apart and see no bad caps. SO now I am going to take some high res pics of the boards so someone else can see these caps. I could be wrong of course.