LCD Desktop Monitor Fading to White, then Black
in [Repair]
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From: saber850 on 9 May 2010 18:04 On May 9, 11:12 am, saber850 <saber...(a)yahoo.com> wrote: > On May 7, 9:06 pm, "Dav.p." <davi...(a)tiscali.it> wrote: > > > Hi, i'm new here and sorry 4 my poor english, first of all this long flame seems to me much > > out of site (? exagerate..?), too much word maybe for a very simple problem, i'm not a tech > > but from the first agree with talks of J.Liebermann, the strange thing i spect from somone that > > suspected the main 5v line that ususally supply the graphic/video chip, so is not (for me) a bad > > idea to test the 5v line on the psu connector to the v.board since you don't found any bulged/ > > dirt capacitor, and if you find the v changes according to the fades then go to order caps, if not > > try at least to measure on the regulator on v.board to see if exit 3,3v fixed or some like it. > > I don't agree to what said, it's a luck that you have 2 equal monitor so in the last if you don't > > find culprit you can swap boards and see > > > bye bye. > > Yes, I've been considering swapping one of the boards between the > monitors. This seems like the easiest way to narrow down the problem. I swapped the power boards in the monitors. The "good" monitor immediately exhibited the problem that the previously malfunctioning one did, while the "bad" monitor works fine (at least, so far). So I'm confident that the problem is from the power board, and given this thread and some web sites, I'll start w/ the caps. Now that I had both power boards to examine, I also noticed that the C110 and C111 caps were replaced by Samsung when I sent the monitor in for repair earlier this year (the last month of its warranty). I'll get the specs of all caps today, find corresponding parts on DigiKey, and post back here for confirmation. I will research this topic on the web, but are the Polymer caps entirely superior to electrolyte ones? Are there drawbacks to polymer caps?
From: Jeff Liebermann on 9 May 2010 18:49 On Sun, 9 May 2010 15:04:59 -0700 (PDT), saber850 <saber850(a)yahoo.com> wrote: >Are the Polymer caps >entirely superior to electrolyte ones? Are there drawbacks to polymer >caps? This article covers most everything: <http://www.capacitorlab.com/capacitor-types-polymer/> Polymer caps solve just about every complaint I can think of with electrolytics. The major benefits are much longer lifetime, lower ESR, and better temp stability. The down sides are the higher cost and that they are available only in fairly low voltages. If you can find them, and can afford the cost, do it. -- 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
From: Dav.p. on 9 May 2010 23:00 > one did, while the "bad" monitor works fine (at least, so far). So you say the bad mon. with the good power board i think... > I'm confident that the problem is from the power board, and given this ok, 1-0 for me... :) (ah it's a soccer score sorry..) >both power boards to examine, I also noticed that the C110 and C111 >caps were replaced by Samsung when I sent the monitor in for repair from what you noticed? The shining solderings? >earlier this year (the last month of its warranty). I'll get the >specs of all caps today, find corresponding parts on DigiKey, and post >back here for confirmation. i think is not so vital to find the specs, only take uF and V and order a good brand of low esr type. (105c) >I will research this topic on the web, but are the Polymer caps >entirely superior to electrolyte ones? Are there drawbacks to polymer >caps? As above i'm not an expert at all but i think.. with a good brand like Sanyo, Rubycon, Panasonic etc, you can go quiet and live life in peace for at least 3-4 years intense-use, it's a good idea replace all area's caps, to be sure.. like i said it's safer and instructive to test the 5v line output for instability, or the 12v if 5v is stable.. but it is no so safe whitout precautions so it's up to you, if the boards stays screwed on the back and face outside is more safe.
From: saber850 on 10 May 2010 12:46 On May 9, 11:00 pm, "Dav.p." <davi...(a)tiscali.it> wrote: > > one did, while the "bad" monitor works fine (at least, so far). So > > you say the bad mon. with the good power board i think... > > > I'm confident that the problem is from the power board, and given this > > ok, 1-0 for me... :) > (ah it's a soccer score sorry..) > > >both power boards to examine, I also noticed that the C110 and C111 > >caps were replaced by Samsung when I sent the monitor in for repair > > from what you noticed? The shining solderings? > > >earlier this year (the last month of its warranty). I'll get the > >specs of all caps today, find corresponding parts on DigiKey, and post > >back here for confirmation. > > i think is not so vital to find the specs, only take uF and V and order a good brand of low esr type. (105c) > > >I will research this topic on the web, but are the Polymer caps > >entirely superior to electrolyte ones? Are there drawbacks to polymer > >caps? > > As above i'm not an expert at all but i think.. with a good brand like Sanyo, Rubycon, Panasonic > etc, you can go quiet and live life in peace for at least 3-4 years intense-use, > it's a good idea replace all area's caps, to be sure.. like i said it's safer and instructive > to test the 5v line output for instability, or the 12v if 5v is stable.. but it is no so safe whitout > precautions so it's up to you, if the boards stays screwed on the back and face outside is more > safe. Yes, I'm confident the the problem is w/ the power board, since that's the only thing that changed, and the problem followed it. The monitor w/ the power board from the non-malfunctioning monitor has been functioning properly for 24 hours. There are three reasons that I suspect the C110 and C111 caps were replaced. The first reason is that all caps across both power boards except those two have a hand-drawn black mark (line on the radius) on top. Those two have slightly shinier solder. And there are small scratches on the underside of the PCB around those caps' pins. As for testing the 5V or 12V lines, that's not easy because the boards are not screwed down. There is a metal plate which sandwiches these boards to the back of the panel, and which provides the mounting point.
From: saber850 on 10 May 2010 16:32
On May 10, 12:46 pm, saber850 <saber...(a)yahoo.com> wrote: > On May 9, 11:00 pm, "Dav.p." <davi...(a)tiscali.it> wrote: > > > > > > one did, while the "bad" monitor works fine (at least, so far). So > > > you say the bad mon. with the good power board i think... > > > > I'm confident that the problem is from the power board, and given this > > > ok, 1-0 for me... :) > > (ah it's a soccer score sorry..) > > > >both power boards to examine, I also noticed that the C110 and C111 > > >caps were replaced by Samsung when I sent the monitor in for repair > > > from what you noticed? The shining solderings? > > > >earlier this year (the last month of its warranty). I'll get the > > >specs of all caps today, find corresponding parts on DigiKey, and post > > >back here for confirmation. > > > i think is not so vital to find the specs, only take uF and V and order a good brand of low esr type. (105c) > > > >I will research this topic on the web, but are the Polymer caps > > >entirely superior to electrolyte ones? Are there drawbacks to polymer > > >caps? > > > As above i'm not an expert at all but i think.. with a good brand like Sanyo, Rubycon, Panasonic > > etc, you can go quiet and live life in peace for at least 3-4 years intense-use, > > it's a good idea replace all area's caps, to be sure.. like i said it's safer and instructive > > to test the 5v line output for instability, or the 12v if 5v is stable... but it is no so safe whitout > > precautions so it's up to you, if the boards stays screwed on the back and face outside is more > > safe. > > Yes, I'm confident the the problem is w/ the power board, since that's > the only thing that changed, and the problem followed it. The monitor > w/ the power board from the non-malfunctioning monitor has been > functioning properly for 24 hours. > > There are three reasons that I suspect the C110 and C111 caps were > replaced. The first reason is that all caps across both power boards > except those two have a hand-drawn black mark (line on the radius) on > top. Those two have slightly shinier solder. And there are small > scratches on the underside of the PCB around those caps' pins. > > As for testing the 5V or 12V lines, that's not easy because the boards > are not screwed down. There is a metal plate which sandwiches these > boards to the back of the panel, and which provides the mounting > point. Here's my first stab at finding replacement caps. I was not able to find any polymer caps to replace these on Digikey or Mouser. I opted for Panasonic if it was available. PCB Designation Farads (µF) Voltage (V) Temp (C) Length (mm) Potential Length (mm) Diameter (mm) Lead Spacing (Board) (mm) Mouser Replacement Mouser Replacement URL C105 150 450 105 41 45 20 7 661-EKMQ451VN151MP40 http://www.mouser.com/Search/ProductDetail.aspx?R=EKMQ451VN151MP40Svirtualkey66100000virtualkey661-EKMQ451VN151MP40 C107 47 50 105 11 24 5 5 667-ECA-1HHG470 http://www.mouser.com/Search/ProductDetail.aspx?R=ECA-1HHG470virtualkey66720000virtualkey667-ECA-1HHG470 C301 680 25 105 17 22 10 5 667-EEU-FC1E681 http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1E681virtualkey66720000virtualkey667-EEU-FC1E681 C302 680 25 105 17 22 10 5 667-EEU-FC1E681 http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1E681virtualkey66720000virtualkey667-EEU-FC1E681 C110 820 25 105 22 24 10 5 598-361R821M025EG0E http://www.mouser.com/Search/ProductDetail.aspx?R=361R821M025EG0Evirtualkey59850000virtualkey598-361R821M025EG0E C111 820 25 105 22 24 10 5 598-361R821M025EG0E http://www.mouser.com/Search/ProductDetail.aspx?R=361R821M025EG0Evirtualkey59850000virtualkey598-361R821M025EG0E C112 330 25 105 14 24 10 5 667-EEU-FC1E331 http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1E331virtualkey66720000virtualkey667-EEU-FC1E331 If this doesn't display well, I can upload the spreadsheet as a PDF somewhere. |