Hanns-G HG281 dumpster find refurb

[c_muck]

Last weekend I spotted this 28-inch Hanns-G monitor sitting next to a dumpster and thought it would be worth it to take it home and see if it worked. At first I plugged it in and nothing happened, so I figured oh well, back to the dumpster. A couple hours later after it had been plugged in for a while I noticed that the power light in the corner had turned on! I hooked up my computer and was quite happy with my find. I then unplugged the monitor to move it to another room, and since then it won't turn on at all, not even the power light in the corner.

So I searched the internet for answers and found this amazing forum! After reading though some other threads concerning this same monitor I had the courage to tear into mine to try and see if I can fix it. Unfortunately, the easily identifiable solution of blown capacitors doesn't seem obvious in my case. None of the capacitors on either my power board or logic board seem especially bloated or leaking. I did, however, notice a suspicious-looking melted area in the middle of the power board on the copper spool thing. (forgive me for not knowing its name, I've attached a close up picture of what I'm talking about) Could this be the source of my problem, and if so would it be relatively easy and worthwhile to fix? Should I still plan on replacing all the capacitors as well?

Thanks in advance.

[Th3_uN1Qu3]

Re: Hanns-G HG281 dumpster find refurb

That's a transformer, and that's glue. It's fine.

You have a classic case of bad caps (they start working when they warm up). Replace the caps even if they're not bloated. What caps are they?

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

A couple hours later after it had been plugged in for a while I noticed that the power light in the corner had turned on! I hooked up my computer and was quite happy with my find.

This sounds like bad caps with high ESR. When the unit is plugged in, there is power going through the lcd. This warms up the capacitors and lowers the ESR (ohms) so that the power light comes on.

An easy way to verify this theory is to use a hair dryer and warm up the capacitors on a "warm setting" say for about 30 seconds to 60 seconds. So unplug the LCD and move the hair dryer around the caps on the power board.

Now plug in the lcd and try powering on.

Unfortunately, the easily identifiable solution of blown capacitors doesn't seem obvious in my case.

Capacitors die from age, heat, and shoddy build quality. Capacitors DO NOT have to be visibly bloated in order to bad. They can be out of tolerance uF (a 1000uF measures 20uF) and/or have high ESR (ohm). A multimeter will be insufficient to test for ESR. For that you need an ESR tester which costs between $50 and $300.

Most members here will recommend that you replace ALL capacitors with reputable brands from reputable sellers. Brands like Rubycon, Panasonic, and United Chemicon are suggested. A list of recommended caps can be found at

https://www.badcaps.net/forum/showthread.php?t=2280

I did, however, notice a suspicious-looking melted area in the middle of the power board on the copper spool thing. (forgive me for not knowing its name, I've attached a close up picture of what I'm talking about)

That is a transformer. The brown melted stuff is likely lacquer from the factory process. That looks normal.

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

This thread with the same monitor in posts #1 through #26 are relevant with "caps looking good" but turn out to have high ESR

https://www.badcaps.net/forum/showthread.php?t=11329

[c_muck]

Re: Hanns-G HG281 dumpster find refurb

Hey guys, so I successfully replaced all the caps on the power board, and now my monitor turns on again! Thanks to everyone here for the information that has been shared which helped me to do this.

I now seem to have another problem though. The monitor turns on fine, but the picture is shaky towards the middle, and after about 30 seconds or so the screen goes black. If I unplug and replug the computer, the picture will come back on, but goes black again soon after. Any ideas on why this would be?

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

The monitor turns on fine, but the picture is shaky towards the middle, and after about 30 seconds or so the screen goes black

1) What brand and series did you use for the replacement caps?

2) If you shine a flashlight onto the lcd screen, can you see your favourite windows wallpaper?

[c_muck]

Re: Hanns-G HG281 dumpster find refurb

I got my caps from digi key, and used the attached product list that I found in another thread as my guide.

I don't see anything when I shine a flashlight at the black screen, but my led does stay blue.

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

I don't see anything when I shine a flashlight at the black screen, but my led does stay blue.

Post a clear focused pictures using the manage attachment function of your logic, power, and inverter board and we can suggest test points.

[c_muck]

Re: Hanns-G HG281 dumpster find refurb

Ok, here are some photos. I tried to get some close of shots of a few of my less-than-stellar solder joints to see if you think any of those might be my problem. In a couple instances the metal ring that surrounds the hole for the capacitor lead broke off when I was taking out my old caps. In those places I just gobbed on some extra solder to make sure the connection would still be alright. The one I am particularly concerned about is in IMG_0117 where the connection I traced for the cap lead goes underneath #223. Is there a way I can beef up this connection, or did I ruin the board altogether when the metal ring broke off?

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

Picture of the inverter board?

[c_muck]

Re: Hanns-G HG281 dumpster find refurb

Picture of the inverter board?

Pardon my ignorance, is the inverter board one of these?

[retiredcaps]

Re: Hanns-G HG281 dumpster find refurb

Pardon my ignorance, is the inverter board one of these?

The long board is the inverter. The other is called t-con (timing control). The caps on the inverter board may be suspect as well and causing your backlights to go out after 30 seconds. Replace them with Panasonic FC equivalents.

Re: your soldering. See this video by CuriousInventor on soldering.

http://www.youtube.com/watch?v=I_NU2ruzyc4

[mockingbird]

Re: Hanns-G HG281 dumpster find refurb

Which dumpsters have you been visiting? Things have been pretty much slim pickings for the last while for me. Or is it that I can only ride for a few hours now that I started smoking a little bit.

[c_muck]

Re: Hanns-G HG281 dumpster find refurb

Just wanted to button up this thread-

I replaced all of the caps on both my inverter board and logic board. In addition to the new caps on the power board which I did before, My monitor is working perfectly! Thanks to everyone who helped me do this!