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Old 12-19-2010, 03:11 AM   #1
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Default Hanns-G HG281D 28" TFT - Multiple Problems


I have the above mentioned monitor and am attempting to repair it.

I bought it used, as is, and had a problem with it right from the get-go.

First, whenever I would use the RGB input with any computer, the video display would have lots of wavy lines moving around on it... much like one sees when viewing certain finely detailed patterns in HD TV broadcasts using an analog TV.

Then, I noticed that after the monitor would stay on for about 5-10 minutes, the pixels on the screen would start to... how would I describe it... well, the black areas would suddenly start getting speckled with more and more white pixels in a seemingly random pattern, and it would generate a faint buzzing/hissing sound, and then would power down into standby mode (power light still on, in the standby color - red/orange/whatever - I'm partially color blind so I just know it wasn't blue!). I would have to turn the power off and wait about 10 minutes or more before it would come out of standby mode.

So I attempted to use the DVI input. This remedied the wavy lines problem, and also seemed to lengthen the time that it would stay on before going into standby. (I should mention that whenever it did go to standby with a DVI input, the pixel issue described above would still occur just before shutdown, but not so pronounced, and without so much, if any, of the hissing as was the case in RGB mode.)

Sometimes I could keep the thing on for 12 hours or more without any problem. Other times it would go off after about 20 or 30 minutes. Whenever it malfunctioned, I would have to cycle the power several times to get it to come out of standby mode. And whenever I would power it down for any reason, even if it was working properly, it would rarely come back on right away (either by using the power switch or by cycling directly at the power cord).

Interestingly, the power button would often fail to work once it was off, and I would have to push it and hold it in, push it multiple times (and any variation/combination of such) to even get the light to come on at all (in standby mode). Once it did come on and come out of standby mode, sometimes it would go right back off again after a few minutes. Other times it would work perfectly for many hours.

The problem seemed to get worse over time. After I had it for about a year, it shut down on me one day and I finally just couldn't get the thing to come out of standby mode at all.

When this happened for the last time, it was a really, really bad time for it to... and I was having a really bad day... So, like a complete imbicile, I got angry and starting bashing the thing around (banging on the back/sides of it), as sometimes this seemed to have helped in the past. But I turned into a little baby throwing a temper tantrum and finally held it over my desk on it's back and dropped it from a height of about 7 or 8 inches multiple times. Finally the power light stopped coming on at all and it was, indeed, completely dead.

FFWD 10 months to today: I decided to learn how to fix it today because I don't want to pay Hanns-G the $200+ they want to replace the faulty board(s) for me. So after researching monitor repair and the layout of this particular model, I opened it up and found that, on the top of one of the heat sinks/covers on the PSU board, there was mark with melted metal where it had obviously shorted out to something. I noted that the casing to which it is installed has a matching mark on it as well

Upon trying to figure out how in the world this could've happened with a clearance of about 1/8" between the two surfaces, with the PCB firmly mounted to the case and the case being a very rigid metal, I noticed that the PCB has a bit of a bow in it - apparently from the excessive heat build up during it's use (this monitor always ran EXTREMELY hot).

So I've I hypothesized that when I dropped it on the desk, the PCB was very pliable due to it's temperature, and the G forces caused it to make contact with the case for a fraction of a milisecond upon impact, thereby causing the short.

So now I have a monitor with multiple problems, the second of which may or may not be related to the same board that was causing the first.

Based on my description of the initial intermittent forced standby problem, does that sound more like an issue with PSU board or with the main board?

And based on the short of the heat sink/cover to the case, is there a group of parts that would most likely have been affected by said short?

I am posting pictures of both boards for your review.

Thanks! And sorry for the long description - I just wanted to be thorough.


(sorry, these are the highest resolution images I can make right now)
Attached Images
File Type: jpg MainBoard-Front.jpg (448.7 KB, 271 views)
File Type: jpg MainBoard-Back.jpg (388.8 KB, 176 views)
File Type: jpg PSU-Front.jpg (650.6 KB, 252 views)
File Type: jpg PSU-Back.jpg (765.7 KB, 175 views)

Last edited by stevekasian; 12-19-2010 at 03:21 AM..
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