Hanns-G HG281D, LCD Monitor no power

[feil]

Re: Hanns-G HG281D, LCD Monitor no power

Hello.
yes you see the screen and windows desktop, so inverter or lamps, should i try a new inverter board?

it would cost me about 35 dollar. or only the caps on the inverter board?

and lamps changing is that even possible?
and thanks

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

Your english is fine. I understand you perfectly.

When the screen goes dark, you'll need to shine a flashlight on it, in a dark room; and see if you can see a picture on the screen. Then it would be the inverter board or a lamp.

[feil]

Re: Hanns-G HG281D, LCD Monitor no power

Hello.
i hope this reads anyone^^

i have also one of the hg218d become from a friend, that was not working anymore.
i have changed all the caps on the power board and all the 470uf 16V and 100uf 16V on the logic board.

the monitor was fine working now for about 1 months and now i have the problem that hes running about 10 minutes and then he screen goes dark,
after it has cooled off, it also works for about 10 minutes and then the screen goes dark.
the power led stays blue

from what i can hear is that the lcd controller board is making noises.
but only when the screen goes dark,
before that eveythings fine and no noieses or anything.

could it be the inverter board or the caps from that?
or that i have get a bad cap somewhere else?

it would be nice if someone has an advice


and sry for my bad english,
I Am from Asutria

[fightforlife]

Re: Hanns-G HG281D, LCD Monitor no power

So I made some unsuspected progress with my hd281D.

long story short:
i didnt get any input on hdmi or vga with different pcs and cables.
After changing all the caps on both boards the problem persists.

Now the news:
i just got a Fire Tv Stick and tried it on the broken monitor and voila. There is a picture! Its not the best quality and the maximum resolution is 720p, but atleast there is some life.
So I tried the Stick with and without extension cord and both is working in 720p. (1080p is not supported by the monitor, it says)
When I try the same extension cord on a working pc with hdmi, there is still no input detected....

How is that possible... any ideas?`Thanks in advance

[avioni]

Re: Hanns-G HG281D, LCD Monitor no power

great discussion. I replaced the 3 known to fail caps on the logic board 100uf 16v my screen was just loosing image randomly but now i must have messed something up bad i only get a red screen. i try reconnecting everything and even resoldering everything but still red screen. any ideas?

[mj2301]

Re: Hanns-G HG281D, LCD Monitor no power

Hey I looked at your soldering work and it looks bad. Some of the joints are missing a good portion of solder. You have to remember that the only thing connecting the capacitors are solder, and if the joints are missing a lot then you will run into stability issues. I had that issue with the logic board giving me lines across the screen. Once I re-soldered the joints the monitor worked perfectly fine.

[krestic]

Re: Hanns-G HG281D, LCD Monitor no power

Wooff, that was a long thread. So, my story: +5VSB only, no PSON. +5VSB stable if the main board detached, and fluctuating +-0.25v if the main board is connected.
shorting +5VSB and PSON with 3.3K powers the power block on but there is some ticking coming from the power board 3-4 ticks per sec. Voltages are fluctating appr. +-0,3. Then the ticking slows down and after appr. a minute stopes. So does the voltage fluctuation.
Than the main board: The signal from the power button goes to RTD2120l MC, and doesn't go any further. I mean there is no outgoing signal changes when you press the power button. Could that be a problem?
All caps on main board are changed as well as smaller ones on the power board.
Appretioate any advice.

[fightforlife]

Re: Hanns-G HG281D, LCD Monitor no power

Basically, you're trying to see if the PC "sees" the monitor as connected.

Ive tested multiple PCs with different HDMI cables and one VGA cable.
None of them detected the monitor. But the monitor knows when a cable is connected oder disconnected (no signal message)

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

and here is the digikey cart sharing (i think this will work)
http://www.digikey.com/short/7rb0vr
Is everything in the digikey cart accurate?

Panasonic FM, FR, and FC are excellent choice of capacitors, so you are good there.
I didn't check if the sizes you picked will work for you, though - mainly because I've never repacced one of these monitors myself and I don't have a list of caps and their diameters. But if you have verified that yourself, you should be good then.

I see only one problem:
The 2x 1000uf 35v caps (P12405-ND) appear to be on back-order - and it will likely take a very long time before you get them. So you may have to pick some other brand and/or series of caps. Try:
Panasonic FR
Nichicon PW, HE, or HW
United Chemicon KY, KZE, or KZN

Also, for the 1000 uF, 16V caps (P12366-ND), it is cheaper to order 10 of them than to order 7 due to price break .

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

Does anyone think the low solder on this chip might be a problem?

Interesting find. The solder does look quite ugly indeed. However, if the chip doesn't run too hot (under 60C), then the chances of the solder cracking due to temperature changes is fairly small. But if you tried everything on your monitor and it still doesn't work, then this might be worth a try. I will say, though, that manually soldering those pins with an iron is quite tricky. Hot air should be somewhat easier... but if you don't have a hot air tool, it's not worth getting one just for the monitor.

But shouldnt there have been at least a slightly change in symptoms after changing the caps?

Not necessarily.
The performance of the new caps, if they have the wrong ESR, could still render the same problem.

Think of this as an expriment. You need to eliminate all sources of "uncertainty" before going to the next step.

But my monitor just stayed black after reboot, it was perfectly fine before!
So my guess is that it isnt a problem with slowly drying caps rather than something that broke because of short hight voltage burst or something similiar. (Probably the monitor-cpu?)

Well, the caps going dry overtime could have caused something else to fail too.

Try this: get either a laptop or a second working monitor to hook up to your desktop (and hopefully, your desktop video card has two monitor outputs).

For laptop: after laptop boots, connect your Hanns-G monitor (try both VGA and HDMI if the laptop has one). See if the computer "recognizes" the monitor (Right Click on desktop and go into "Sceen Resolution" [W7] or Properties>Settings [XP]).

For desktop PC: let it boot to you desktop screen with the working monitor. Now connect the Hanns-G monitor, and repeat same procedure as above.

Basically, you're trying to see if the PC "sees" the monitor as connected.

Ive read that some guys put their graphicscard into the oven for a short time. Can i use this method with the mainboard or will the caps get damaged from the heat?

Electrolytic caps will certainly get damaged from the heat. You have to remove them all before trying this.

[_BtB_]

Re: Hanns-G HG281D, LCD Monitor no power

hey thanks for the help
the pics posted of the power board are not the same as mine, I managed to snap a few pics but they are not of the best quality. Its the best I could do without buying a camera.

So I will just recap the entire 2 boards and see how that goes. here is the cap list

logic board:
3 x 470uf 16v
12x 10uf 25v
5x 100uf 16v

power board:
2x 1000uf 35v
2x 680uf 25v
4x 10uf 50v
1x 33uf 35v
2x 1000uf 16v
1x 100uf 16v
1x 220uf 10v
1x 220uf 25v

and here is the digikey cart sharing (i think this will work)
http://www.digikey.com/short/7rb0vr

Is everything in the digikey cart accurate?

thanks

[fightforlife]

Re: Hanns-G HG281D, LCD Monitor no power

Does anyone think the low solder on this chip might be a problem?

What is the best way to make sure these soldering points make a correct connection?

Ive read that some guys put their graphicscard into the oven for a short time. Can i use this method with the mainboard or will the caps get damaged from the heat?

My problem is that i only have a rather large soldering iron. So I cant really solder on this small pins. i would only try to heat them i little without fully melting to give them a better connection...

[fightforlife]

Re: Hanns-G HG281D, LCD Monitor no power

Are these pictures after you changed the caps? If so, I see one potential problem: you used Teapo capacitors (or so it appears to be by their vents) - those are known to be quite unreliable. You might also have used the wrong series of Teapo (i.e. not low ESR or not low enough).

The voltage on the regulators you measured appears to be fine, but bad power/excessive ripple due to faulty caps (or caps not adequate for the job) could still cause issues. I had one LCD monitor where all voltages came up properly and appeared "normal". However, the image on the display would not always display properly - sometimes, I would just get a bloack screen, other times random pixels. I replaced just a few of the output caps on the power supply with proper caps and that got the monitor working perfectly afterwards. So it is important to use good caps.

What qualifies as good caps? - The major Japanese brands: Panasonic, Nichicon, Rubycon, and United Chemicon. And you also have to get the right low ESR series. So...
Panasonic: FC, FM, and FR
Nichicon: PW, PS, PM, HE, HD, HW
Rubycon: ZL, ZLH, ZLJ, ZLG
United Chemicon: KY, KZE, KZN, LXV, LXY, LXZ\

Do NOT use eBay if you are new to buying capacitors - there are way too many counterfeit capacitors on there, especially from China/Hong Kong. Local shops likely won't have what you need either. The best place to get capacitors is online through some of the better-known part suppliers, such as Digikey, Mouser, RS Online, and Farnell/element14.

I just saw your answer, thanks!
i got all the capacitors from Conrad here in Germany. Sadly they only provide one cap for a special rating (V and F). So there wasnt really a choice.
But shouldnt there have been at least a slightly change in symptoms after changing the caps?

Most of the people with bad caps in this thread first did have only little problems and with time they got bigger up to total failure of the monitor.
But my monitor just stayed black after reboot, it was perfectly fine before!
So my guess is that it isnt a problem with slowly drying caps rather than something that broke because of short hight voltage burst or something similiar. (Probably the monitor-cpu?)

If i find the caps mentioned by you, I probably will try them out!

[TVRepairNoobie]

Re: Hanns-G HG281D, LCD Monitor no power

Does anyone think the low solder on this chip might be a problem?

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

I hope somebody is still reading this

Problem: Always get "no signal" message when connecting or disconnecting hdmi.

I already changed all the caps on both boards.

Here are some high resolution pics:
1
2
3
4

Are these pictures after you changed the caps? If so, I see one potential problem: you used Teapo capacitors (or so it appears to be by their vents) - those are known to be quite unreliable. You might also have used the wrong series of Teapo (i.e. not low ESR or not low enough).

The voltage on the regulators you measured appears to be fine, but bad power/excessive ripple due to faulty caps (or caps not adequate for the job) could still cause issues. I had one LCD monitor where all voltages came up properly and appeared "normal". However, the image on the display would not always display properly - sometimes, I would just get a bloack screen, other times random pixels. I replaced just a few of the output caps on the power supply with proper caps and that got the monitor working perfectly afterwards. So it is important to use good caps.

What qualifies as good caps? - The major Japanese brands: Panasonic, Nichicon, Rubycon, and United Chemicon. And you also have to get the right low ESR series. So...
Panasonic: FC, FM, and FR
Nichicon: PW, PS, PM, HE, HD, HW
Rubycon: ZL, ZLH, ZLJ, ZLG
United Chemicon: KY, KZE, KZN, LXV, LXY, LXZ\

Do NOT use eBay if you are new to buying capacitors - there are way too many counterfeit capacitors on there, especially from China/Hong Kong. Local shops likely won't have what you need either. The best place to get capacitors is online through some of the better-known part suppliers, such as Digikey, Mouser, RS Online, and Farnell/element14.

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

To both of you. It sounds like the caps on the power board. If your power board is the same as this attached picture, replace the 3 circled in red. Those 3 are known to dry up. If after the power board is working, you notice any fuzziness or pixelation; replace the 2 caps on the main/logic board. (in the 2nd picture)

On this power board the manufacturer tended to bend the legs of the caps completely over on the pads. Making them a little harder to remove without lifting the pads. You'll want to remove the solder with desoldering braid, then heat the area with the tip of the iron and take a very small screwdriver and bend the pins up a little. The goal is to remove the cap without lifting the pads.

For BtB - There's some great videos on youtube on how to solder properly. I'd practice on an old spare board first. Then solder the new caps on the power board. Good luck

[Marauder2003]

Re: Hanns-G HG281D, LCD Monitor no power

My problem is similar to BtBs problem

Not sure which board in my HG281D needs caps. For a long time it took many presses of the on button before the screen came on. Then one day the power went out and when it came back on the monitor did to. Apparently the on-off system remembers the last state. This lead me to use a power cord with an on-off switch so I did not have to use the monitors switch.

The monitor takes over 15 seconds to come on. And the longer it is off the longer it takes to come on. But once on it is fine. All inputs work. No flickering.

Any idea which board needs caps?

[_BtB_]

Re: Hanns-G HG281D, LCD Monitor no power

Hello, have a question about this monitor.
When it is turned on, the blue light would come on but it would take a long time for the picture to show. I guess once it is properly heated, the picture would show and everything would be good until windows puts the monitor in sleep mode or I turn off the monitor.

Does this sound like a capacitor problem? I do not see any bulges in the caps, but the caps could be dried causing high esr correct? I will get some pictures when the sun is out later on today.

Also I remember this forum having a tutorials section where one could learn basic electronics through the links provided, is this still a thing? Maybe it was another forum or something... But if you could recommend books or video tutorials for the absolute beginner I would appreciate it, thanks

[fightforlife]

Re: Hanns-G HG281D, LCD Monitor no power

Yeah, i checked the cable and laptop on another monitor. There they are working fine.

Thank you very much. I think verifiyng the videosignals and processor is something i cant do with my limited electrical supply and knowledge.

I will wait another week if someone has another idea. After that its going into the trash if no one is interested.

perhaps i should mention that this problem did start after rebooting the pc.

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

"PS_On (the black cable between power and main) measures 0.02V when amber led and 2.84V when display on.... somewhere in this thread was said that it had to be over 3V?!" >2.5 = ON, <1V = OFF.
At this point it seems to me that the logic board is not sensing the Video signals (you have already verified that the PC and the cable are OK), you will have to use the scope to find out if the Video and sync signals get all the way to the processor or not and to do that you will need the diagram also.