Hanns-G HG281D, LCD Monitor no power

[jetadm123]

Re: Hanns-G HG281D, LCD Monitor no power

Great work MicroBell1! Thanks for sharing your success story. Really surprised you were able to use only a 20W soldering iron. That lead free solder can sometimes be a real pain.

[MicroBell1]

Re: Hanns-G HG281D, LCD Monitor no power

Thanks guys for all your help!

@retiredcaps... Only 3 or 4 bad traces in 2.5 years? I tied ya in about 15 min in 1 repair.....lol. After the first screwup I did diagram each trace and to which componet it was connected. Came in handy when I screwed up again...hahahaha.

@momaka... I did use 60/40 so I hope it holds. Came up fine this morning and it's pretty cold here in PA so it should hold the hot/cold cycle ok.

@jetada123... As did I. I expected it take a tad longer to heat the solder but was suprised how fast it melt. That said the 20watt had trouble (as expected) on a motherboard because of the multi layer board. Doable but a slow process for sure.

[mc900fthanna]

Re: Hanns-G HG281D, LCD Monitor no power

Replaced the Bridge rectifier as suggested by selldoor - it was testing open between the ac negative and the DC negative. the replacement one i got did not, so it seems that was a broken piece. All 8 caps in center section of board replaced now as well. When i put her all back together, still no picture, however, i can plug it in now w/o blowing a fuse and i the power LED light to go from blue to amber. When i attach the monitor to a video card, windows detects it and recognizes its max resolution - so that means some of the logic is alive too. no 12 or 24v power detectable yet, so what pieces should i check next?

[Crais]

Re: Hanns-G HG281D, LCD Monitor no power

My monitor is just outside of warranty and decided to start flickering both vertically and horizontally. The picture will come on and off several times until the monitor heats up a little then it will stay on and start the jittering/flickering. The picture will sometimes be perfect for a short period after it stops going on and off.

I've spent some time reading through some of this thread and it seems that bad capacitors are the likely culprit. I have very little electronic experience and my soldering skills are lacking.
I have a very basic dmm that cannot test capacitance.
I don't have much light to work with now and I neglected to get photos of what I think is the inverter board for the backlight, so the quality on those are lower. I can get better pictures tomorrow if needed.

I've uploaded some pictures and resized/cropped. If more detail is needed in an area please let me know.

[selldoor]

Re: Hanns-G HG281D, LCD Monitor no power

Are you saying the pictures are not your boards?

Have you tried the monitor on another pc or as external on a laptop

[Crais]

Re: Hanns-G HG281D, LCD Monitor no power

Are you saying the pictures are not your boards?

Have you tried the monitor on another pc or as external on a laptop

The boards are mine, the lighting wasn't ideal and I'm working with a phone for a camera.

I've tried it on another PC (it's on another one now). I've been using it as a secondary monitor so I could easily watch it's behavior.

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

Can you try setting the PC to the lowest resolution and see if the monitor will work without flickering or going black?

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

Can you try setting the PC to the lowest resolution and see if the monitor will work without flickering or going black?

We know this one well eh bud. He has the symptoms of those small caps on the power board that dry out next to the smitchmode transformer. And those 2 caps on the main board next to the voltage regulators.
The 2 on the main board...Photo courtesy of the man above me. Budm
http://s807.beta.photobucket.com/use...62664929957295

The attached photo shows the caps that need to be replaced on the power supply. The ones circled in red for sure. And you might as well replace the ones circled in blue while your at it. Photo, courtesy of me

I read where you mentioned you are not very skilled at soldering. You might want to ask a friend that is. Good luck. ~L-J-7~

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

Yes, I believe that is what he has.

[Crais]

Re: Hanns-G HG281D, LCD Monitor no power

Lumberjack, the board you linked looks a tad different from mine.
I'm a little lost as to which caps I should start with on mine. I've got a ton of old parts to practice soldering while I wait on replacement parts to arrive so I'm going to attempt the job myself. Need to learn one way or other.

I'm about to put it all back together and try a lower resolution. Should I leave the refresh at 60Hz?

Thanks for your help, guys.

[Crais]

Re: Hanns-G HG281D, LCD Monitor no power

Powered on, perfect picture, changed the resolution to 800x600x60Hz, flickering started immediately. Changed res to 1280x800x60 and 20 minutes in, no problems. Probably just coincidence.

Edit: Started back up, doesn't look nearly as bad, but till doing it.

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

You do have bad caps on the main board, that is one of the symptom.

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

Lumberjack, the board you linked looks a tad different from mine.
I'm a little lost as to which caps I should start with on mine.

I apologize. I didn't even take a closer look at your power board. Looks like they used a different one.

You do have bad caps on the main board, that is one of the symptom.

Yes, I'd replace those 2 on the main board first. That should fix the problem. If you have any problems with the monitor firing up after that, replace the 5 small caps in the middle of the power board.

Those 2 on the main board are through hole soldering. It's a little more challenging than when a component is attached to one side of a pcb board. The solder is actually inside the hole. So you might want to practice on a motherboard, or a board with similar solder joints.

[holbs]

Re: Hanns-G HG281D, LCD Monitor no power

two hours to read this thread from start to finish.

i have the same lumberjack issues with my HF289H.

i am actually kind of excited to give this a shot (hay..i cant lose) will be filling out the correct description tomorrow with detailed sunny bright pictures.
now to go see just what kind of solder iron / multimeter i have laying in the garage

[awPhil]

Re: Hanns-G HG281D, LCD Monitor no power

Hey guys, have been stalking this thread for a bit and finally worked up enough courage to give this repair a shot.

The monitor was RMA'd last year for bad capacitors - the standard "won't turn on consistently that escalated into won't turn on at all." Worked fine until a week ago, where it'll stay on for a few seconds, then the picture drops out and the blue light flashes. Out of warranty now.

All of the caps look fine (save for maybe the three in the last picture - are those normal?), but I understand that they can be dried out.

I don't have an ESR, and could use some help picking out which caps should be replaced on which boards. Should I just replace all of them? Or could it be another issue?

Thanks!

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

two hours to read this thread from start to finish.

i have the same lumberjack issues with my HF289H.

i am actually kind of excited to give this a shot (hay..i cant lose) will be filling out the correct description tomorrow with detailed sunny bright pictures.
now to go see just what kind of solder iron / multimeter i have laying in the garage

Welcome to badcaps! You read the entire thread. Wow, good for you. So you probably have a pretty good idea of what the problem is. Great.
If you have the same board that I have posted before; than the problem is almost always those small caps in the middle of the power board drying out that I had circled. You'd never find anything in my garage. Unless you had a map
Here's the best soldering video I have seen, and was referred to me by retiredcaps. http://www.youtube.com/watch?v=I_NU2ruzyc4

Hey guys, have been stalking this thread for a bit and finally worked up enough courage to give this repair a shot.

The monitor was RMA'd last year for bad capacitors - the standard "won't turn on consistently that escalated into won't turn on at all." Worked fine until a week ago, where it'll stay on for a few seconds, then the picture drops out and the blue light flashes. Out of warranty now.

All of the caps look fine (save for maybe the three in the last picture - are those normal?), but I understand that they can be dried out.

I don't have an ESR, and could use some help picking out which caps should be replaced on which boards. Should I just replace all of them? Or could it be another issue?

Thanks!

Welcome to badcaps also! Your board is a little different than the one with the big metal heatsinks that I am used to. But it definitely sounds like it could be the caps. Your board has caps that are easily accessable; so you could replace them all. Or you could start with the 5 smaller ones located all around the center of the board, in case they are dried out; which is common with this model. That'd be a good start. If that doesn't work; we'll need to start diagnostics, and you'll need a good digital multimeter. ~L-J-7~

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

awphil, set the PC video resolution to the lowest setting and see if the pictures will stay on, if it does, then the caps by the two LDO regultors need to be replaced for sure beside the caps on the power supply.

[awPhil]

Re: Hanns-G HG281D, LCD Monitor no power

awphil, set the PC video resolution to the lowest setting and see if the pictures will stay on, if it does, then the caps by the two LDO regultors need to be replaced for sure beside the caps on the power supply.

I hooked everything back up and on the initial power on, before I could adjust resolution, the picture dropped out and the blue light started flashing. I adjusted the resolution to the lowest, but still no picture/wont turn on, just a flashing blue light. Unplugged/replugged cables for a bit to no avail. One thing I noticed was when I had the hdmi cable plugged in, the blue light would completely turn off. As soon as I unplugged the hdmi from the monitor, the blue light would resume flashing.

Left it alone for maybe a half hour, with the power cable in, and finally there was a solid yellow light. Plugged hdmi in, on low-res, and it stayed on for an hour. Then I switched the resolution back up to the highest setting for an hour, but the picture didn't drop again. Tried turning it on/off multiple times, unplugging/replugging power to replicate the problem, but it seems to stay on now. Does it have something to do with it being heated up?

Also, I do have a multimeter, but I have no idea which parts to test.

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

That can be due to the ESR of the caps go down when the caps are heated up.
I suspect the C80 and C83 on the main board for the 3.3V and the 1.8V LDO regulator, also can be the caps in the power supply board. You can try the C80, C83 first.
You can use a canned air duster, use it upside down so it becomes cold spray, then you can cool those two caps and see if the picture will go out.

[videoman5]

Re: Hanns-G HG281D, LCD Monitor no power

Hello, I am new to this forum, but not to replacing bad caps.

My HG281D has been blinking on and off for the last week or so. It only seems to do it when there's a lot of black on the screen. Like on webpages with black backgrounds, and what have you. The power LED stays blue the entire time, so I am thinking it's something to do with the logic board.

Does anyone have a plain text list of the caps that are on the PSU and the logic board? I'm probably going to replace them all.