Hanns-G HG281D, LCD Monitor no power

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

I only replaced the power supply board caps (except for the large one).

I'm thinking of maybe going back and doing the other board as well. Probably I would order them from digikey if I had a list of all the caps I needed. There are also some larger caps running along the edge of the board attached to the screen, I wonder if I should replace those as well,... although I don't the cap values for that either.

I've repaired about 10 of these. It's always the same caps. The ones on the power board. And the two on the main/logic board as Budm mentioned. If you replace just those 2 you'll probably be fine. Many, many, of the other caps are still good. And it's a waste of time and money to even replace them. Try replacing these 2.

[invenio]

Re: Hanns-G HG281D, LCD Monitor no power

So did you replace the two caps by the voltage regulators on the logic/main board since most kits have the caps for the power supply repair but not the caps for the main board?

I only replaced the power supply board caps (except for the large one).

I'm thinking of maybe going back and doing the other board as well. Probably I would order them from digikey if I had a list of all the caps I needed. There are also some larger caps running along the edge of the board attached to the screen, I wonder if I should replace those as well,... although I don't the cap values for that either.

[rspendl]

Re: Hanns-G HG281D, LCD Monitor no power

Sorry, the numbers of problematic capacitors on the main board are C80 and C83.

[rspendl]

Re: Hanns-G HG281D, LCD Monitor no power

Just finished repairing four (4) HG281D monitors that all failed after approx 5 years of use. Two did not turn on at all, both had fluctuating +5VSB. Replacing the capacitor C603 of the power supply (22 uF / 35 V) fixed both of them.

The other two did turn on and +5VSB was stable, but did not get the signal (displayed "no signal" message). Replacing capacitors C61 and C69 on the main board (100 uF / 16 V next to a regulator) fixed them. Just a hint for other people looking for a quick fix and not wanting to spend more than a dollar for spare parts :-)

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

So did you replace the two caps by the voltage regulators on the logic/main board since most kits have the caps for the power supply repair but not the caps for the main board?

[invenio]

Re: Hanns-G HG281D, LCD Monitor no power

Well... unfortunately I don't think it was a complete fix. I did notice that if I turn the monitor off after it's been awhile, then wait for it to completely cool down, and then turn it back on,... there was some flickering. It's definitely much better than it was before and I don't have to wait 10 minutes for it to "warm up." Maybe some other caps are going bad on the other boards? For now it's still very usable so I don't regret doing the work. If it gets worse I will probably try recapping the 2nd board.

[invenio]

Re: Hanns-G HG281D, LCD Monitor no power

I FIXED IT!!!!

I own a HG281D and for many months I had an issue that was described on here. It would basically take several minutes for my monitor to "warm up" and before it did it would turn on and off. After it was warm, it would then stay on. I basically tolerated this for a very long time (probably 6 months or so) and then on occasion it would temporary black out for a second or two depending on what was displayed on screen.

Started doing some research and found this thread. I was able to read through the first 20 pages,... sorry couldn't make it all the way. I ended up ordering a repair kit off of ebay for about $12 (free s/h). I was thinking of buying individually off of digikey but I was worried about the cap sizes not fitting where they were close together. Also, they included some solder remover braid which was helpful. I would highly recommend these kits as they save a lot of time in figuring out what exactly needs to be ordered (yeah, they may cost a few bucks extra).

I'm pretty bad with a soldering iron but I got through it and put everything back together. Magically, about 5 extra screws materialized in the process.

Anyway, the moment of truth came when I plugged it in and bang... it's fixed. I am really happy as I really like the monitor otherwise and saved me a few hundred dollars in replacement costs.

I should note that after examining the power supply and controller board I did not see any "bulging" or leaking caps. So if your having a similar problem but the caps "look good," I would still recommend trying to replace them.

Here are some pictures of the boards, although I couldn't see anything abnormal about them.

PS - Thanks for all the posters on here and the valuable info and pictures people have posted (it really helped when I took off two caps that looked the same yet were different ratings and I didn't know which one went where).

[r3z0nate]

Re: Hanns-G HG281D, LCD Monitor no power

I know there are different models of the logic board but are their different versions of power supply boards? I happened to order (1) 1000uF 35v and (2) 1000uF 25v capacitors going off a list, but have (2) 1000uF 35v capacitors on the power supply board.

I was told I could use the 25v capacitors but would rather repair it properly. If it is just an overkill I'd like to use what I have and get this thing fix.

On a side note, after replacing just the one capacitor my power issues went away but the screen was solid red. Unfortunately the flat cable that goes to the screen broke off on the corner. It should still make the connection, but does anything think that is most likely the culprit? Thanks.

[banem]

Re: Hanns-G HG281D, LCD Monitor no power

Hi folks.

Wow, 33 pages of posts... and I spent time reading all.

OK, to the point - I have Viewsonic 2835 which has same power supply as Hanss HG281D and a bit similar main board.

I had similar issue - first it would not turn on so I have to remove power cord, put back, remove, put back until it goes on, until 2 days ago when it goes silent dead.

1 year ago I had issue with house power supply. I lost 0V cable so in every wall connector I got around 400V. Since I know why that happens, I immediately switch off whole house power supply, but while I did that, monitor release lots of smoke so whole room was full of it. Since then problems with monitor started and I think something died (maybe part of some IC's). That time varistor protected a monitor and he released that magic smoke.

So I found advises here and I give a try to fix it. A little background - I am into electronic for more than 30 years, few years worked professionally, otherwise mostly as every day hobby, so I have no issues to fix almost anything that does not require heat gun.

First I was about to replace 2 caps on main board in power supply - they were inflated suggesting they lost the value. I can measure capacitance only so I did - both are around 10 uF instead 470!! And monitor worked 3 days ago. I assume they are similar in value and position as in monitor in subject:



I had on hand 2 470/35V not low ESR so I put them instead. I put all back together, not working.

Here is where they are and how they look:



OK, then I went to change those 3 suggested in this thread, 2x22 uF and 1uF. When I took them off I measured capacitance and found 1/4 of capacitance on all.

Since I was lazy to order and wait, I took old Akai CD player, it is like 15 years old and found 2 capacitors 22uF. Measured by capacitance, they are OK (I do not have equipment to measure ESR though) and it appears they are not low ESR. Also I took one new 1uF/160V that I had on stock and replaced all 3. Put all back together, its working! It even turn off / on on every power button click.

Thanks you all! I love the picture this monitor have, actually I hate all those LED litted with cold blue picture (that cannot be set not to be bluish). I am very happy to have this thing working again!

Finally, here is what I replaced, cost is close to zero. I do not think you must use top quality capacitors although it is best to use them to avoid any future issues, as tolerance is very high. My monitor worked with above values!



And all back together in place.

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

I would recommend 50~60 Watts iron, and the trick to remove old component is to add more solder to the joint first.

+1
The Radio Shack desoldering iron is not very powerful - probably just barely enough to remove caps on the logic board. Okay, don't get me wrong, it's a nice desoldering iron, but it's better suited for removing ICs on older single-layer boards.

[budm]

Re: Hanns-G HG281D, LCD Monitor no power

I would recommend 50~60 Watts iron, and the trick to remove old component is to add more solder to the joint first.

[mj2301]

Re: Hanns-G HG281D, LCD Monitor no power

Here are some pictures of the boards. Also, would this suffice to repair the logic board: http://www.ebay.com/itm/Hanns-G-HG28...item2339edb9a5 (the new soldering iron would be nice, my current iron is a Weller SP23L). Suggestions for an iron/caps/solder etc would be greatly appreciated!

The scratches are from my iron slipping while I was attempting to remove the old caps.

Don't get the cheap irons on eBay. Go to Radio Shack, they have the desoldering iron and the soldering iron for about $15 each. These will last you for several years of use compared to the cheap ones.

As for the capacitors, I would recommend Panasonics or Nichicon, as they were highly rated for quality on this thread. I bought them through DigiKey, again recommended on the thread. These are the capacitors for both the logic board and the power supply.

Here I have attached the parts list along with the ratings and the quantity. Hope it helps. **Verify your logic board and the power supply capacitor ratings before purchase, as each monitor has slightly different versions.**

[mj2301]

Re: Hanns-G HG281D, LCD Monitor no power

Got my monitor fixed! Thank you to everyone who set this forum up and the people who helped along the way.

The Problem
Originally the monitor was flickering off then on, and on top of that it would start developing white vertical lines.

The Struggle
I replaced every capacitor on the logic board and the power supply. The logic board was the most difficult, because the leads are so close to one another. Plus, when I started I didn't have a desoldering iron, lesson learned, and I got one. In addition, I had two of the capacitor's traces on the power supply lift, so that was hell.

The Added Headache
Finally when I put everything back together the damn thing had green dots everywhere. I took it apart one last time, thinking that it must be a bad connection somewhere on the logic board.

The Solution
Sure enough I went over the capacitors with a bit more solder, verifying the contacts were completely covered. For added measure, I used my heat gun to round out the soldering, moving quickly as to avoid damage to the ICs and the processor. Once that was done, I put the damn thing back together for the last time. Finally this time around it worked!

The Prize

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

The scratches are from my iron slipping while I was attempting to remove the old caps.

Do you have to press very hard on the iron to get the solder joints to melt? If yes, my guess would be that you're doing so because your iron doesn't get hot enough. I used to do that too when I first started encountering lead-free joints. Higher wattage iron helps. As I mentioned, 40W is a minimum. 50W to 60W will make it much easier on these multi-layer boards with lead-free solder. Adding flux to the joints before trying to melt them with your iron also hels a lot.

Here's a few inexpensive ones (recommended if you solder rarely):
http://www.ebay.com/itm/60W-IRON-SOL...item2c8828fff7
http://www.ebay.com/itm/Delcast-60W-...item233ce20c70
http://www.ebay.com/itm/YongFeng-Dur...item4868efe0c8
These aren't very high quality, so don't leave them unattended. But as Lumberjack777 noted, they should work.

I don't recommend getting that kit you linked to. For one thing, you don't know the brand and series of the caps included in the kit - they could be good quality or they could be cheap generics that will fail very quickly. Moreover, these are for the PSU/inverter board. Also, the soldering iron is only rated for 30W - that is barely enough to do the job. I just tried to change a small cap on a very old graphics card (GeForce RivaTNT) with my 35W iron, and it barely got hot enough to pull the old cap out.

Lastly, based on the picture of the power supply board you included, I do see some green Taicon caps that may be responsible for causing no-power issue. In general, Taicon caps aren't exactly bad (compared to other crappy capacitor brands), but they aren't exactly reliable either, if heat is involved (which is often true in LCD monitors).
Here's a list of caps on the power supply board that may be responsible for causing no-power:
C8, C31, C32, C33
Although, if you are replacing those, you might as well do CS18, CS20, and all of the other green Taicon caps.

As for the logic board, looks like you have the caps put on the right way now.
So it could be that the power board is not providing power to the logic board or could be that a regulator on the logic board is bad (but I doubt it). This, you can check with a multimeter. First check if there is 5V comming from the PSU board. Should be present on a pin or two on either connectors CNS2 or CNS3 (or both?). Measure voltages with the black probe on your multimeter connected to ground (i.e. any metal part on the case of the monitor, as long as the power supply is installed in the monitor). If there is 5V, then check the voltage on the tabs of the two regulators on the logic board - U7 and U8 (top left, in this picture).

Let me know what results you get. BE CAREFUL when taking measurements on the power supply. In particular, take note of the white line on the bottom of this picture:
https://www.badcaps.net/forum/attach...8&d=1407544792
It separates the primary and secondary sides. Anything on the primary side is dangerous to touch when the monitor is plugged in.

[Lumberjack777]

Re: Hanns-G HG281D, LCD Monitor no power

Ok. First of all that "kit" is for the power/inverter board. Not the main/logic board. The Soldering iron is an el-cheapo that you can get on eBay for around 5 bucks. But they usually work. And burn out after a few hours.
You could buy a similar iron on eBay. (5 bucks or so) Buy your caps from Digi-Key. Buy the solder anywhere (leaded with flux core). And you'd be set.

In the 4th picture the 2 holes look rather large. Did you pull out the metal plated core by chance? Like a metal tube. If so, you'll need to bridge to the components they were connected to.

Also, when soldering, sit up close and brace the front of your body against the bench. And put your elbow on the bench (the one holding the soldering iron). This will keep the iron from moving while soldering.

[davisgarth09]

Re: Hanns-G HG281D, LCD Monitor no power

Here are some pictures of the boards. Also, would this suffice to repair the logic board: http://www.ebay.com/itm/Hanns-G-HG28...item2339edb9a5 (the new soldering iron would be nice, my current iron is a Weller SP23L). Suggestions for an iron/caps/solder etc would be greatly appreciated!

The scratches are from my iron slipping while I was attempting to remove the old caps.

[johnwin909]

Re: Hanns-G HG281D, LCD Monitor no power

Actually yes I did clean the screen with a liquid cleaner. I will try that, thank you.

[selldoor]

Re: Hanns-G HG281D, LCD Monitor no power

Its along the bottom -yes? Do you clean the screen with liquid/foam cleaner?

Could be a damaged panel

First thing to try would be to remove clean and replace the lvds cable.

[johnwin909]

Re: Hanns-G HG281D, LCD Monitor no power

Hello, my monitor recently started showing rows of blacked out pixels and corruption. Anyone have any idea if this may be a problem with bad capacitors?

http://tinypic.com/r/14b3rll/8

[momaka]

Re: Hanns-G HG281D, LCD Monitor no power

I had a hell of a time trying to get the old caps off, It took 10-15 minutes before my iron was hot enough to get the solder to melt.

Sounds like you have a weak iron. What wattage is it rated for? If less than 30W, you'll need something better. "disposable" 40-60W irons can be bought for cheap online (like less than $5 shipped). If you are not going to do repair too much, it's probably better to get one like that (although, I will also caution you to never leave such irons unattended, since they are not exactly high quality).
Also, try going for something with a big, chisel or bevel -type tip. Small tips loose their heat quickly and make it hard to solder with. They are usually more suite towards small surface mount components.

Lastly, I recommend to add a tiny bit of fresh solder to your iron's tip before trying to solder or desolder anything - this will yield better heat transfer between the tip of the iron and the component's lead, and will make the soldering much easier. Should take no more than 2-5 seconds to heat a joint to get the solder to flow smoothly.

I believe one of the two caps replaced may have been in backwards, that is correct.

Those caps may be damage now. Possibly something else too. But we will see with the pictures, and if you have a multimeter, we can troubleshoot.