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samsung syncmaster 203b

 
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davet
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PostPosted: Thu Nov 12, 2009 2:29 am    Post subject: samsung syncmaster 203b Reply with quote

I was told if the screen is black but you can see images when shining a flashlight on the screen, the inverter needs to be replaced. Is this true???
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jts1957



Joined: 24 Nov 2008
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PostPosted: Thu Nov 12, 2009 3:18 am    Post subject: Reply with quote

Or the inverter board is being told NOT to stay "ON." For example if a CCFL bulb is broken. Wink
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PostPosted: Thu Nov 12, 2009 7:02 pm    Post subject: Reply with quote

I am handy but do not have equipment to do diagnostics... can this blackout problem be easily fixed. I have the flat screen monitor case open but not sure what to look for.

Any help??
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FalconFour



Joined: 22 Nov 2009
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Location: Fresno, CA

PostPosted: Sun Nov 22, 2009 10:01 am    Post subject: Reply with quote

Wait, wait, before you go digging into the screen to replace the CCFL's or shoveling out money for an inverter... I've got a little (a lot, rather Wink) experience with this same issue. The monitor sitting on my desk right now was junk-piled for the same problem (flashes for a second then dim image), and the monitor I just repaired earlier tonight (also junk-piled for not turning on anymore) were both fixed by replacing capacitors.

Capacitors in LCD monitor power supplies are of very poor quality, it seems. Apparently quality power is of little concern for such damn expensive devices. Especially considering they have no fans and get no cooling... but anywho. Quite likely, the problem is that the backlight (which uses the most power) comes on, drains the (dead) capacitors, causing power ripple that disorients the inverter and shuts it off. When the backlight inverter goes into failure mode and shuts down, the power ripple smooths out and the image stays on the screen. But the light never comes back on - the inverter has no way to detect that the power smoothed out, and even if it did, it would go into the same cycle over and over.

Long story short, your problem is quite likely capacitors, as usual. Nasty little liquid buggers. Heat causes their value to subtly change while running, which in turn causes them to heat up (as the monitor continues to draw the same amount of power from them), and eventually bulge and leak. Most of the time, you can find the bad capacitors by the ones having bulging tops (which should be flat) or pressed-out bottom rubber caps (making it so you can't wiggle it from side to side - or leaking onto the board).

If you find one blown capacitor, it's entirely likely that all the rest need to be replaced as well. With capacitors as cheap as they are (often under 50 cents each), it's a good idea to simply replace all the filter capacitors in one go. Grab the values (volts and microfarad (uF) - like "25v/1000uF") from the capacitors - the filter capacitors are all large and grouped together. Just grab the values from the larger ones - don't worry about the tiny ones elsewhere, or the one really large capacitor by the AC jack unless it's bulging or leaking. Also, check for bulging/leaking capacitors on the LCD logic board if it has any (I had one with that once). Run to mouser.com to look them up. Capacitors are under "Passive Components" -> "Capacitors" -> "Aluminum electrolytic capacitors (Leaded)" (where "leaded" means they have wire leads - not that they have lead). Enter the values and search. I usually go for Nichicon or United Chemi-Con capacitors, but that's just because I'm cheap. If you find them, Panasonic capacitors seem to be a golden choice for a slight premium. Just add your choice to the cart, buy 'em, and wait for 'em to come in. Then, you'll have a new LCD! Cool

Hope this helps!
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davet
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PostPosted: Fri Dec 04, 2009 12:07 am    Post subject: samsung syncmaster 203b Reply with quote

I replaced the capacitors. It still will not light. Can still see the page if a light is flashed on screen. What is the next part to check/replace?

Thanks in advance
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Anupun
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PostPosted: Sat Dec 12, 2009 9:56 am    Post subject: Re: samsung syncmaster 203b Reply with quote

davet wrote:
I replaced the capacitors. It still will not light. Can still see the page if a light is flashed on screen. What is the next part to check/replace?

Thanks in advance


I have had exactly the same problem. I replaced all capacitors but still the monitor still won't light. I searched the internet and found that in one case the 3A fuse (green color adjacent to 820 uF capacitor) was blown out and needed to be replaced as well. In my case the fuse looks apparently fine but when I checked with the meter I found that the fuse was broken. So I replaced the fuse and my monitor has bot back to work normally again. I hope your case would be similar to mine.
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damic
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PostPosted: Mon Jan 18, 2010 3:47 pm    Post subject: Reply with quote

Hi, ive got the same screen and ive fixed the fuse but still no light from it. But it produces a high tone.
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Tortax



Joined: 02 Sep 2008
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PostPosted: Sun Sep 19, 2010 12:11 am    Post subject: Reply with quote

Mine broke too.

One thing is for sure, they have indeed inserted bad quality caps in this model. Replacing them will fix the monitor in some cases but not all.

Re-soldering the HI-Voltage pads can also be a fix.

Has anyone found the service manual for this monitor?
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