LCD Desktop Monitor Fading to White, then Black
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From: Grant on 2 May 2010 18:07 On Sun, 2 May 2010 14:14:33 -0700, "William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote: >As I mentioned in the OP, when the monitor is malfunctioning, I have >swapped the DVI cables between the monitors. When doing so, the >malfunctioning monitor continues to malfunction while the other >monitor (the one which has never malfunctioned) continues to function >properly. So from this, I believe the computer & video card are >functioning properly. Am I making a valid assessment here? > >Yes, of course -- that's Troubleshooting 101. > >What's going on is that the video information is being lost, and the pixel >"twist" is being forced all the way one way, then all the way the other way. >As to the cause... > I like the 'crazy LCD controller' idea -- bad connection somewhere making it cycle through the brightness range -- doesn't seem like faulty components could make an LCD smoothly cycle brightness how you describe? So I think the culprit is the controller PCB in the LCD, unless bad power is provoking the thing to craziness? Grant. -- http://bugs.id.au/
From: Grant on 2 May 2010 18:13 On Sun, 02 May 2010 14:10:47 -0700, Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Sun, 2 May 2010 07:22:40 -0700 (PDT), saber850 <saber850(a)yahoo.com> >wrote: > >>Both monitors are a Samsung SyncMaster 204B. > >Thank you for supplying the maker and model number. > >This might be of interest: ><http://pavel.kirkovsky.com/2009/03/samsung-syncmaster-204b-repair/> ><http://www.djhome.net/tips/samsungsyncmaster204T.htm> >I've seen both problems on the bench with similar Samsung models. > >My usual method is to replace *ALL* the large value electrolytic >capacitors. The labour is less to do it at one time, than to spend >any time finding which one or two is the culprit. Make sure you buy >105C or 125C replacement caps as the 85c variety don't last. Larger >values and voltage ratings are fine, but watch out for package sizes >and lead spacing. Agree with you, there's usually room to squeeze in higher voltage caps, and, with switching regs you could drop capacitance a little bit[1] and not harm the circuit performance -- ripple current rating of the caps is more important than the capacitance value of replacement cap. [1] Got some 390/63 and 820/25 105'C low ESR caps I'd use instead of 470/35 and 1000/16 in a repair. Grant. -- http://bugs.id.au/
From: Pete Bertini on 2 May 2010 18:34 "Jeff Liebermann" <jeffl(a)cruzio.com> wrote in message news:qvprt5hb6kgboh7hs40153neg5nismmipk(a)4ax.com... > On Sun, 2 May 2010 07:22:40 -0700 (PDT), saber850 <saber850(a)yahoo.com> > wrote: > >>Both monitors are a Samsung SyncMaster 204B. > > Thank you for supplying the maker and model number. > > This might be of interest: > <http://pavel.kirkovsky.com/2009/03/samsung-syncmaster-204b-repair/> > <http://www.djhome.net/tips/samsungsyncmaster204T.htm> > I've seen both problems on the bench with similar Samsung models. > > My usual method is to replace *ALL* the large value electrolytic > capacitors. The labour is less to do it at one time, than to spend > any time finding which one or two is the culprit. Make sure you buy > 105C or 125C replacement caps as the 85c variety don't last. Larger > values and voltage ratings are fine, but watch out for package sizes > and lead spacing. > > -- > Jeff Liebermann jeffl(a)cruzio.com > 150 Felker St #D http://www.LearnByDestroying.com > Santa Cruz CA 95060 http://802.11junk.com > Skype: JeffLiebermann AE6KS 831-336-2558 I was thinking capacitor too. In the old analog days one would searching for a leaky coupling cap in the video amplifiers :)
From: saber850 on 2 May 2010 20:09 On May 2, 11:46 am, "David" <some...(a)somewhere.com> wrote: > >> >saber850 <saber...(a)yahoo.com> wrote in message > >> >news:2468c376-1884-4039-af3a-55c41cedb3c6(a)k29g2000yqh.googlegroups.com... > >> >> Hi, > > >> >> My LCD desktop monitor has been exhibiting a problem > >> >> for over 1 year. > >> >> It is out of warranty and I would like to fix it. > > >> >> The problem is that the monitor displays the picture, > >> >> and then > >> >> gradually fades to white, and then gradually fades to > >> >> black. > > >> >> The monitor does not exhibit the problem all the time. > >> >> It comes and > >> >> goes. I do not have a procedure which triggers the > >> >> problem; it seems > >> >> to be random. Sometimes it will behave this way for > >> >> only a few > >> >> minutes, while other times it will behave like this > >> >> for weeks. > > >> >> I do not do anything to trigger the problem, other > >> >> than have the > >> >> monitor powered on. > > >> >> I have two of these monitors. I bought both monitors > >> >> at the same time. > >> >> Both monitors are connected to the same video card > >> >> (nVidia) via a DVI > >> >> connection. Only one of the monitors exhibits the > >> >> problem--the other > >> >> continues to function properly. When the monitor > >> >> exhibits the > >> >> problem, I can swap the DVI cables and the other > >> >> monitor continues to > >> >> function properly. So I do not believe the problem is > >> >> my video card or > >> >> computer. > > >> >> I do not know of a method to get the monitor out of > >> >> this problem > >> >> state. I've tried cycling the power to the monitor, > >> >> and I've tried > >> >> rebooting the computer. Neither method fixes the > >> >> problem. The only > >> >> thing I can do is wait for it to fix itself. But > >> >> eventually, it > >> >> malfunctions again. > > >> >> A video of the problem occurring is available here: > >> >>http://www.youtube.com/watch?v=W7YpFZVRjcE > > >> >> Best regards, > >> >> Nick > > Does this monitor have buttons on the front to control > brightness? Could one of those be stuck or shorted? > > David It has buttons on the front, but not to control the brightness or contrast directly--those are available a couple levels deep in the menu. When the problem returns, I will try adjusting the brightness & contrast via the monitor to see what happens.
From: Mike Tomlinson on 2 May 2010 20:13
In article <2468c376-1884-4039-af3a-55c41cedb3c6(a)k29g2000yqh.googlegroup s.com>, saber850 <saber850(a)yahoo.com> writes >The problem is that the monitor displays the picture, and then >gradually fades to white, and then gradually fades to black. Erk. That video you put on Youtube is kinda creepy! Are you sure it's not demonic possession? I don't think it's a backlight problem. It looks more like a contrast issue. I have a similar Samsung monitor (SyncMaster 2343 widescreen) with touch controls and It looks like yours has those too. In your situation, the first thing I would do is whip the back off and disconnect the touch control board from the main board and see if the problem stops. I'm wondering if a "button" is stuck. Then I'd probably move to gently heating some of the chips, particularly those on the back of the LCD panel, with a hairdryer to see if the fault is temperature-related. I know you say you want to try and fix it, but if it's a panel fault, the monitor's fit only for scrap. -- (\__/) (='.'=) Bunny's thinking about giving Windows 7 (")_(") a go despite what he's said about it... |