Samsung TFT 204b: extreme slow response

T

thomas albrecht

Guest
Dear all,

My Samsung 204B has a *very* long response time, black-white several
secs.. white-black ~0.5 sec. This happened instantly while in
operation, and persists ever since. Happens both on DVI and VGA, with
different graphic cards (NVIDIA GF 7600GS and ATI 7500) as well as
without any signal input at all, then showing the wandering "Check
signal cable" window. I opened the case, the caps look OK to me, no
bulging or leaking.

Here's a video showing the slow response. The graphics should be
updated instantly. Instead, it appears more like a fade-in
http://www.youtube.com/watch?v=8tcwLBV3jxs

Any hints are greatly appreciated.
Thomas
 
On Tue, 13 Apr 2010 02:01:11 -0700 (PDT), thomas albrecht
<taradi2010@googlemail.com> wrote:

Dear all,

My Samsung 204B has a *very* long response time, black-white several
secs.. white-black ~0.5 sec. This happened instantly while in
operation, and persists ever since. Happens both on DVI and VGA, with
different graphic cards (NVIDIA GF 7600GS and ATI 7500) as well as
without any signal input at all, then showing the wandering "Check
signal cable" window. I opened the case, the caps look OK to me, no
bulging or leaking.

Here's a video showing the slow response. The graphics should be
updated instantly. Instead, it appears more like a fade-in
http://www.youtube.com/watch?v=8tcwLBV3jxs

Any hints are greatly appreciated.
Thomas
Click to expand...
Did you try a different monitor to eliminate any possibility it is GUI
effects from Winders?
 
On Apr 13, 11:01 am, thomas albrecht <taradi2...@googlemail.com>
wrote:
Dear all,

My Samsung 204B has a *very* long response time, black-white several
secs.. white-black ~0.5 sec. This happened instantly while in
operation, and persists ever since. Happens both on DVI and VGA, with
different graphic cards (NVIDIA GF 7600GS and ATI 7500) as well as
without any signal input at all, then showing the wandering "Check
signal cable" window. I opened the case, the caps look OK to me, no
bulging or leaking.

Here's a video showing the slow response. The graphics should be
updated instantly. Instead, it appears more like a fade-inhttp://www.youtube.com/watch?v=8tcwLBV3jxs

Any hints are greatly appreciated.
Thomas
Click to expand...
Does the same happen once you are logged in? Did you try the monitor
on another computer (i.e. e.g. without GRUB)?
 
Thank you for your replies!

Does the same happen once you are logged in? Did you try the monitor
on another computer (i.e. e.g. without GRUB)?
Yes, same effect during POST, OS booting, logged in (text mode), and
Click to expand...
GUI running.
Connecting the faulty monitor to another machine did not help.

Did you try a different monitor to eliminate any possibility it is GUI
effects from Winders?
If I connect another monitor to my primary machine, everything shows
Click to expand...
up fine, so it's definitely a problem with the monitor itself.
 
On Apr 13, 4:32 pm, thomas albrecht <taradi2...@googlemail.com> wrote:
Connecting the faulty monitor to another machine did not help.
Why? If it still shows as faulty if you connect it to another machine,
Click to expand...
it is clearly a monitor problem.
 
Connecting the faulty monitor to another machine did not help.
Why? If it still shows as faulty if you connect it to another machine,
it is clearly a monitor problem.
Of course you're right. I just wanted to express that my problem with
Click to expand...
this monitor persists, even when I connect it to another machine. So
it's not a problem with that specific machine or graphics card or
such.
 
Why? If it still shows as faulty if you connect it to another machine,
it is clearly a monitor problem.
And I didn't mean to say your post wouldn't be helpful, of course!
Click to expand...
 
Hi!

It sounds like a signal processing problem. While I doubt that it will
help, have you tried just unplugging the monitor from power and
letting it sit for a while?

Anywhere from several hours to overnight would do. It doesn't cost
anything to try...

William
 
On Apr 13, 4:58 pm, thomas albrecht <taradi2...@googlemail.com> wrote:
Why? If it still shows as faulty if you connect it to another machine,
it is clearly a monitor problem.

And I didn't mean to say your post wouldn't be helpful, of course!
Click to expand...
No problem, Thomas. I was tired ;-).

Trying William's suggestion does no harm, and that could be tried. In
such situations, anything needs to be tried, particularly the obvious.

Habitually, TFTs monitors do or do not work. I mean... you turn them
on, and either everything's right or nothing works. That is my point
of view, but I am not the only one to preach in this.
 
Hi William!

have you tried just unplugging the monitor from power and
letting it sit for a while?
Click to expand...
Thanks for your suggestion! Actually, it has been sitting powered off
& disconnected for several months after it broke. I only recently
leaned about the many problems with bulging capacitors of this
particular TFT, so I decided to give it a try and look inside. The
youtube video, however, I took just the other day, so, unfortunately,
this seems to be more like a long-term problem...

Thomas
 
Hi William!

have you tried just unplugging the monitor from power and
letting it sit for a while?
Click to expand...
Thanks for your suggestion! Actually, it has been sitting powered off
& disconnected for several months after it broke. I only recently
leaned about the many problems with bulging capacitors of this
particular TFT, so I decided to give it a try and look inside. The
youtube video, however, I took just the other day, so, unfortunately,
this seems to be more like a long-term problem...

Thomas
 
Hi William!

have you tried just unplugging the monitor from power and
letting it sit for a while?
Click to expand...
Thanks for your suggestion! Actually, it has been sitting powered off
& disconnected for several months after it broke. I only recently
leaned about the many problems with bulging capacitors of this
particular TFT, so I decided to give it a try and look inside. The
youtube video, however, I took just the other day, so, unfortunately,
this seems to be more like a long-term problem...

Thomas
 
On 13 Abr, 11:01, thomas albrecht <taradi2...@googlemail.com> wrote:
Dear all,

My Samsung 204B has a *very* long response time, black-white several
secs.. white-black ~0.5 sec. This happened instantly while in
operation, and persists ever since. Happens both on DVI and VGA, with
different graphic cards (NVIDIA GF 7600GS and ATI 7500) as well as
without any signal input at all, then showing the wandering "Check
signal cable" window. I opened the case, the caps look OK to me, no
bulging or leaking.

Here's a video showing the slow response. The graphics should be
updated instantly. Instead, it appears more like a fade-inhttp://www.youtube.com/watch?v=8tcwLBV3jxs

Any hints are greatly appreciated.
Thomas
Click to expand...
This fade looks so nice it seems a feature instead of a fault. Have
you checked all menu options to ensure some weird option has not been
enabled?

Carefully observing the video reveals that going from white to black
is immediate but the opposite is not. The effect reminds me of a
digital clock with weak battery. It could be some weak voltage from
the power supply, probably a bad capacitor.
 
Hi Jeroni!

This fade looks so nice it seems a feature instead of a fault. Have
you checked all menu options to ensure some weird option has not been
enabled?
So maybe I should sell this monitor for it has this extremely rare,
Click to expand...
special feature? :) Nope, unfortunately, there are no menu options
like that...

It could be some weak voltage from
the power supply, probably a bad capacitor.
OK, thanks for the hint. That model is known for having problems with
Click to expand...
capacitors, but commonly described symptoms are different from what I
observe. I'm going to change the capacitors, anyway, and keep you
posted.

Thomas
 
On Tue, 13 Apr 2010 02:01:11 -0700 (PDT), thomas albrecht
<taradi2010@googlemail.com> wrote:

Dear all,

My Samsung 204B has a *very* long response time, black-white several
secs.. white-black ~0.5 sec. This happened instantly while in
operation, and persists ever since. Happens both on DVI and VGA, with
different graphic cards (NVIDIA GF 7600GS and ATI 7500) as well as
without any signal input at all, then showing the wandering "Check
signal cable" window. I opened the case, the caps look OK to me, no
bulging or leaking.

Here's a video showing the slow response. The graphics should be
updated instantly. Instead, it appears more like a fade-in
http://www.youtube.com/watch?v=8tcwLBV3jxs

Any hints are greatly appreciated.
Thomas
While it isn't obvious, an LCD monitor breaks down into several
Click to expand...
electronic sections. Power supply, inverter / backlight, logic
(signal processing) card, and LCD panel.

1. Check the output voltages of the power supply. Yes, I know the
caps look good, but a quick check of the actual voltages MIGHT pickup
a problem.

2. The logic card contains several voltage regulators to provide the
proper voltages for the processor and it's support components, and
often for the LCD panel. These are tyoically a three pin device with
tab. Byu Googling the part number on these devices you can determine
the output voltage. Verify those voltages. While it is unlikely an
incorrect output voltage would cause the symptoms you describe, it's
worth the try.

3. The LCD panel usually contains an electronics card (often conceled
under a metal cover) which generates the voltages and signals
necessary for the proper operation of the panel. I suspect one of
these voltages is missing. This is going to require a LOT of
detective work to analyse, so try the easier stuff first.

PlainBill
 
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