LCD Desktop Monitor Fading to White, then Black
saber850
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
N_Cook
news:2468c376-1884-4039...@k29g2000yqh.googlegroups.com...
Can you observe discrete jumps in the fade, ie stepped.
Is it a backlight problem? if so perhaps find the brightness control line to
the inverter and break there and add your own subcircuit perhaps. First
monitor that line as maybe a fault inside the inverter chip
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm
saber850
> saber850 <saber...@yahoo.com> wrote in message
Thanks for the quick response. I do not observe discrete jumps in the
fading--it seems very smooth to me.
I do not know if it is a backlight problem; how can I tell?
bi...@love.ranch
I don't think it is a backlight issue
My bet is a circuit problem with something common to all colors.
The brightness increases to max, then it goes negative to black. Then
it pops back to normal.
A lot of monitors have everything wrapped up in one chip.
Some ICs may drive the monitor directly.
Look for unstable supply voltage.
If the voltage is going on/off abruptly but has a big cap on the line
that would explain it.
bi...@love.ranch
wrote:
A backlight gives general brightness to an image.
if it is out, the video will still be there and u can see the image if
u shine a light on the screen - effectively replacing the backlight.
your issue looks like the video is changing - not a backlight issue.
check the PS voltages first.
saber850
> On Sun, 2 May 2010 00:25:15 -0700 (PDT), saber850 <saber...@yahoo.com>
The problem isn't occurring at the moment. When it returns, I will
try shining a light at the screen to determine if the problem is the
backlight.
Regarding the supply voltage: both monitors (as well as the computer
itself) get their power from an APC UPS. When the problem returns, I
will try using the outlet directly on the wall.
saber850
One thing I forgot to mention about the video is that it is not
demonstrating the typical "end" of this problem.
Typically, the monitor fades to all white, then to all black (as
captured in the video), and that's it; it will stay black. It
typically does not cycle the way it does in the video, at least not
indefinitely. It may cycle several times, but within 1 and ~5 cycles
(usually just 1 cycle), it will stay in the "black" state.
saber850
> On Sun, 2 May 2010 08:21:04 +0100, "N_Cook" <dive...@tcp.co.uk>wrote:
>
>
>
> >saber850 <saber...@yahoo.com> wrote in message
> What brand/model card with NVidia chip?
>
> Does the monitor have a DSUB I/O?
> Does the video card have a DSUB I/O
>
> The symptoms don't describe an inverter problem to me
> but rather an LCD matrix drive, possibley PSU derived.
Both monitors are a Samsung SyncMaster 204B.
The video card is a ASUS EN7600GT.
The monitors have 1 DSUB I/O port and 1 VGA I/O port. I've only ever
used the DSUB I/O.
The video card has two DSUB I/O ports. Each one is connected to a
monitor.
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?
Is the PSU typically isolated from other circuitry in the monitor such
that it can be replaced?
David
Does this monitor have buttons on the front to control
brightness? Could one of those be stuck or shorted?
David
Sjouke Burry
ambient light, try different viewing angles and light angles.
If you can still sortof see a picture, it is the backlight.
The slow fade suggests the invertor,or its powersupply circuit.
hr(bob) hofmann@att.net
>
> - Show quoted text -
I don't have any suggestions, but it is definitely Not the backlight.
With a fading backlight the picture would just get darker and darker,
there would be no video reversal such as shown in the video.
Plain...@yahoo.com
wrote:
>On May 2, 9:40�am, Meat Plow <mhyw...@yahoo.com> wrote:
The problem indicates an problem with the video controller IN THE
MONITOR. The Samsung 204s (and other Samsungs) have a bad reputation
for this reason. A slow fade to white can be a problem with the power
to the LCD panel itself, a fast fade to black can be caused by the
inverter. A slow fade to black MUST originate from the video
controler.
Open up the monitor, using all applicable precautions. On the video
controller should be several three terminal devices, but labeled with
a U number (as a hypothetical example, U404). Those are voltage
regulators. It is remotely possible that one of those may be putting
out an incorrect voltage. The last two digits in the part number will
be the output voltage. Again, a hyprtetical part number - L117N33B is
a 3.3 volt regulator.
PlainBill
Jeff Liebermann
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 je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jamie
Are you connected to a Laptop ? is power saving kicking in an option
available in your LCD if the battery is getting low?
Maybe we went over that already, I'm too tired to look back.
William Sommerwerck
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...
Grant
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/
Grant
>On Sun, 2 May 2010 07:22:40 -0700 (PDT), saber850 <sabe...@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/
Pete Bertini
"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:qvprt5hb6kgboh7hs...@4ax.com...
I was thinking capacitor too. In the old analog days one would
searching for a leaky coupling cap in the video amplifiers :)
saber850
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.
Mike Tomlinson
s.com>, saber850 <sabe...@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...
Mike Tomlinson
>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. Sensible, logical fault-finding.
>Is the PSU typically isolated from other circuitry in the monitor such
>that it can be replaced?
It depends on the specific monitor. Some have an external PSU brick, if
yours are those then try swapping them over. If the PSU is internal it
will probably be on its own board which can be removed and swapped out.
How old is the monitor?
saber850
> On Sun, 2 May 2010 07:22:40 -0700 (PDT), saber850 <saber...@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 je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Skype: JeffLiebermann AE6KS 831-336-2558
This is great info; thanks. The website links you found refer to the
problem as "flickering". Is that the condition my monitor has, given
the video I posted?
saber850
wrote:
If it is the invertor or the power supply circuit, would either be
worth repairing/replacing instead of replacing the entire monitor? Is
there any part of an LCD monitor whose expense would not justify its
replacement, and to simply replace the monitor as a whole?
saber850
<jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:
No, this is one of my desktop monitors, and my desktop is not
configured to sleep or hibernate. The second monitor which is
connected to the same video card continues to function properly while
the other malfunctions. So I don't think it's a problem of effect of
the video card or computer.
saber850
> In article <2468c376-1884-4039-af3a-55c41cedb...@k29g2000yqh.googlegroup
> s.com>, saber850 <saber...@yahoo.com> writes
Yeah, I was also a bit disturbed by the video when the picture's color
inverts. I've changed my background so if I capture another video of
the malfunctioning problem, it won't contain a person.
If the problem were related to a "stuck" or "sticking" button on the
face of the monitor, I'd expect the problem to exist all the time, or
at least after I use the buttons. But neither is the case for me.
The problem will start at a seemingly random time, and stop after a
seemingly equally random duration. In particular, I rarely use the
monitor's buttons except for power.
I was also thinking about applying heat to the back of the monitor to
see if that triggers the problem. If that triggers it, does that
suggest a cold solder joint?
Thanks for the info about the worth of the panel.
saber850
> In article <ac15e6c5-a222-4cdb-a450-475b3d0a2...@s29g2000yqd.googlegroup
> s.com>, saber850 <saber...@yahoo.com> writes
This monitor does not have an external PSU brick; so I assume the PSU
is internal. According to the following link, this monitor's power
supply and inverter boards are integrated into one unit (http://
pavel.kirkovsky.com/2009/03/samsung-syncmaster-204b-repair/).
I purchased the monitor new in 2007.
Jeff Liebermann
wrote:
>On May 2, 5:10�pm, Jeff Liebermann <je...@cruzio.com> wrote:
>> 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. �
>This is great info; thanks. The website links you found refer to the
>problem as "flickering". Is that the condition my monitor has, given
>the video I posted?
No, it's not the same. What's probably happening is that as your
power supply warms up, the cazapitors are starting to also get hot. My
guess(tm) is that the power supply output voltages drop, causing the
odd changes to white and black. The symptoms of having the wrong
power supply voltage vary radically with the type of circuit and which
capacitors are a problem. I've seen flickering, fades, time delayed
sudden failure, smoke, fire, and most commonly, just plain no picture.
Given a specific single component failure, it's possible to predict
the symptoms. Given multiple partial failures, it's at best a guess.
Open up the monitor (it's a royal pain), replace all the big caps
whether they look bad or not, and live happily ever after. If you're
into being sure, I suggest you look into purchasing or building an ESR
(equivalent series resistance) meter, as you're guaranteed to run into
this problem in other devices that use electrolytics (motherboards,
TV's, power supplies, monitors, game boxes, router, etc). I use mine
far too often.
<http://www.ludens.cl/Electron/esr/esr.html>
<http://www.anatekcorp.com/blueesr.htm>
<http://www.flippers.com/esrktmtr.html> (I have this one)
<http://www.midwestdevices.com/index.html>
More good reading on LCD repair:
<http://www.ccl-la.com/blog/index.php/category/monitor-repair/>
Note how just about all the failures are electrolytic capacitors.
Here's your Syncmaster 204 page:
<http://www.ccl-la.com/blog/index.php/samsung-214t-repair/>
Note the they're symptoms include a "dark picture". Hmmmm...
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeff Liebermann
wrote:
>If it is the invertor or the power supply circuit, would either be
>worth repairing/replacing instead of replacing the entire monitor? Is
>there any part of an LCD monitor whose expense would not justify its
>replacement, and to simply replace the monitor as a whole?
The Samsung SyncMonster 204/214 is all one big board. There are
replacement boards available on eBay but they tend to have the same
problem that you're trying to fix.
Sending the monitor to the recyclers for such a simple problem will
surely bring down upon your head the wrath of all repairmen,
ecologists, and toxic waste handlers. To maintain your karma, you
must at least make an attempt at repair.
Incidentally, having two identical monitors is a bad idea. Sympathetic
failure and contagious failure modes has been known to propagate
between the bad monitor and the good. I would keep them apart just to
be safe.
Mike Tomlinson
<je...@cruzio.com> writes
>Incidentally, having two identical monitors is a bad idea. Sympathetic
>failure and contagious failure modes has been known to propagate
>between the bad monitor and the good.
Yeah, I know. Just had two Iiyama 20" TFTs (used side by side with a
spanned desktop) fail on me. Expensive lesson.
Mike Tomlinson
.com>, saber850 <sabe...@yahoo.com> writes
>This monitor does not have an external PSU brick; so I assume the PSU
>is internal. According to the following link, this monitor's power
>supply and inverter boards are integrated into one unit
Don't think so. The photos in your link show that the power board is
separate. It would be unusual for the PSU and driver electronics to be
integrated into a single board. It's also obvious that it's been
designed down to the lowest price possible.
>(http://
>pavel.kirkovsky.com/2009/03/samsung-syncmaster-204b-repair/).
Ugh. The state of these caps. Samsung have skimped on the components
and their users are now paying the price. Bad form.
>I purchased the monitor new in 2007.
I suggest as a first step you do what the link above suggests and
replace the few caps indicated, and see how it goes.
Jeff Liebermann
wrote:
>In article <h9est5dts76ogd6n7...@4ax.com>, Jeff Liebermann
><je...@cruzio.com> writes
>
>>Incidentally, having two identical monitors is a bad idea. Sympathetic
>>failure and contagious failure modes has been known to propagate
>>between the bad monitor and the good.
>
>Yeah, I know. Just had two Iiyama 20" TFTs (used side by side with a
>spanned desktop) fail on me. Expensive lesson.
That might be a different problem. The warranty timer chip found in
most electronic devices may have been triggered. The manufacturer
sets the warranty countdown timer to induce a failure immediately
after the warranty expires. When the power supply blows up, and
produces a continuous clicking sound, I tell the customer that's the
warranty timer still running.
<http://pinktentacle.com/2010/01/secret-sony-timer-kills-products-after-warranty/>
N_Cook
Could placing a small 12V fan temporarily, at least, in that area be a
diagnostic tool ?
William Sommerwerck
> Sympathetic failure and contagious failure modes has been
> known to propagate between the bad monitor and the good.
> I would keep them apart just to be safe.
Uva uvam videndo varia fit, right?
Adrian C
> Incidentally, having two identical monitors is a bad idea. Sympathetic
> failure and contagious failure modes has been known to propagate
> between the bad monitor and the good.
It's not only that. There is a grating feeling when two otherwise
identical items have one that shows signs of minor inferiority. It's a
sick child, something that is crying out for some attention.
Ye feel you should be doing something about the one that is failing, but
the affliction is so slight that technically it's not a worthwhile
process of either taking the cover off or approaching the service agent
with complaints.
However, that feeling is however a stress to be remembered and
eventually dealt with as with all the other stresses one unfortunately
collects.
Now, if you only had one of the item and that fault was so minor, you'd
probably be not so aware of the problem, and certainly not so aware of
the stress ...
Life is simpler. I'm going to disconnect one of my stereo speakers and
live with mono. ;-)
--
Adrian C
saber850
> On Sun, 2 May 2010 17:53:14 -0700 (PDT), saber850 <saber...@yahoo.com>
> Skype: JeffLiebermann AE6KS 831-336-2558
Very helpful, thanks.
saber850
> On Sun, 2 May 2010 17:58:59 -0700 (PDT), saber850 <saber...@yahoo.com>
> Skype: JeffLiebermann AE6KS 831-336-2558
I'm all for repairing it, but I just want to make sure the repair is
cost effective. From the information I've received from this group,
and websites, it seems the repair will be very inexpensive if it's
just some capacitors.
Is there a way I can gain confidence that the problem is w/ the
capacitors, before opening it up?
saber850
> Jeff Liebermann <je...@cruzio.com> wrote in message
>
> news:9edst5drns9dhhvmb...@4ax.com...
>
>
>
> > Skype: JeffLiebermann AE6KS 831-336-2558
>
> Could placing a small 12V fan temporarily, at least, in that area be a
> diagnostic tool ?
Yes, I considered this. Unfortunately, as I described, the problem is
very random. For example, it has not surfaced in over a week. So by
trying to cool it, I don't know if it's actually helping, or luck.
The same problem applies to the suggestions I've received to replace
the caps outlined on that website. While I'd be happy to do it, I
won't really know if it has helped for a couple months.
One thing I'd really like is to find a trigger for this problem. I
will try heat today. Is there a way to "stress" the monitor's
electronics, to try reproducing the issue? Would changing the image
rapidly have any effect? Should I display a solid color (perhaps
white) on it?
With a reasonably reliable repro procedure (even if it takes hours), I
can then get more info, and attempt to fix it, all while having some
confidence that my changes have either helped or not.
Jeff Liebermann
<http://alkek.library.txstate.edu/swwc/ld/ldex081a1.html>
I don't think Samsung uses grape juice in their capacitors.
Monitor failures really are contagious. In about 2004, I purchased 9
almost identical Dell systems, all with E173FPF(?) LCD displays. They
worked just fine for 3 years, when they started failing. The ones
that were the warmest and powered on the longest failed first. Within
about 2 months, 6 had developed bad capacitor failure symptoms. What
I found amazing was there was one monitor that was left in the box for
about 2 years. It was used to replace the first monitor failure, and
promptly died about 6 months later. Apparently, they age in the box.
When asked by the owner what was happening, I joked that such failures
were contagious. Unfortunately, my explanation leaked all over the
company with predictable embarrassment. I had to write a company wide
memo explaining what was really happening, what I was doing to fix it,
and apologize for my bad joke. (However, I didn't promise not to do
it again).
Jeff Liebermann
wrote:
>Is there a way I can gain confidence that the problem is w/ the
>capacitors, before opening it up?
Drugs work well for improving confidence. I find that I perform my
most heroic feats of daring and self-endangerment when thoroughly
doped to just below the point of going comatose. This steadies the
hand, improves on my diagnostic abilities, and opens me to a variety
of unusual approaches. The only problem is that I have difficulties
remembering what changes I've made while under the influence and have
therefore resorted to using a camcorder or digital camera. This helps
answer the inevitable questions "What was I thinking"?
I'll refrain from recommending specific controlled substances and
prescription drugs as each technician responds differently. For
starters, anti-depressants and anti-anxiety drugs work well for
elevating one's self-confidence.
<http://www.alphacalm.com/anti-anxiety-drugs/>
However, if the chemical confidence builder solution is not for you, I
suggest you purchase an ESR tester (see previous rant), and test the
capacitors in the circuit. Yes, it works without removing the caps.
Also, look for bulges, leaks, brown goo, and oozing rubber plugs.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
saber850
So I tried various techniques to try reproducing the problem today,
all to no avail. I tried heat. I displayed a solid white image--with
the brightness & contrast at their max level--for several hours
straight; nothing. I turned it off for ~4 hours, and when I turned it
back on, the problem repeated itself. So clearly heat is not a
trigger, not is prolonged use. Unfortunately, the "randomness" of the
problem persists.
Here's more observations:
When the monitor is in it's "black" state, it's not as if the monitor
was off--there is a very low level of light on the screen, so it's
more of a dark gray than black. Is this the backlight?
With the monitor in it's "gray/black" state, I pointed a flashlight at
the screen at all angles & at a close distance. I do not see any of
the image.
I noticed that as the problem was occurring, and the screen was fading
first to white, and then to gray/black, the image is not being
updated. I moved the mouse over to that screen while the fading was
occurring, but the mouse on that screen did not move. Does this
suggest a defective video board?
I also tried adjusting the brightness & contrast, but I couldn't,
because the on-screen menu does not show up.
Jeff Liebermann
wrote:
>So I tried various techniques to try reproducing the problem today,
>all to no avail.
I don't mean to be overly critical, but I think I see a problem. You
remind me of something I had to deal with when training technicians in
a past life. I referred to it as "Circle the wagons. The Indians are
attacking". This was in reference to the tendency for some techs to
march around the problem area, gain a little more insight, but burn
huge amounts of time going literally in circles. The Indians never
had a chance, after tiring their horses, by going in circles around
the wagons. Both you and the attacking Indians would be far more
effective with a direct assault on the problem. At some point, you
will need to dive into the LCD monitor and get your hands dirty. No
amount of additional insight or diagnostics are going to prevent this
from happening. Even if you isolate the problem to a single capacitor
and totally undestand the failure mechanism, you'll still need to
crack the case and do the necessary parts replacement. Might as well
get it over with now (before your horse gets tired).
<http://www.ccl-la.com/blog/index.php/samsung-214t-repair/>
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
William Sommerwerck
>> all to no avail.
> I don't mean to be overly critical, but I think I see a problem. You
> remind me of something I had to deal with when training technicians
> in a past life. I referred to it as "Circle the wagons. The Indians are
> attacking". This was in reference to the tendency for some techs to
> march around the problem area, gain a little more insight, but burn
> huge amounts of time going literally in circles. The Indians never
> had a chance, after tiring their horses, by going in circles around
> the wagons. Both you and the attacking Indians would be far more
> effective with a direct assault on the problem. At some point, you
> will need to dive into the LCD monitor and get your hands dirty. No
> amount of additional insight or diagnostics are going to prevent this
> from happening. Even if you isolate the problem to a single capacitor
> and totally undestand the failure mechanism, you'll still need to
> crack the case and do the necessary parts replacement. Might
> as well get it over with now (before your horse gets tired).
> http://www.ccl-la.com/blog/index.php/samsung-214t-repair
Excellent points, that need to be repeated often.
They're related to the issue of whether you're trying to figure out exactly
what's wrong, or simply getting the unit working again. Often (too often),
you have to abandon the analysis, and "dig in".
My guess is that this problem is related to the power-supply voltages for
the video driver circuits. Second guess would be a bad video driver. (I
don't know whether it's a board or a single chip in this unit.)
saber850
wrote:
Yes, I understand your point.
I think I'm more apt to approach this cautiously for several reasons.
One is that I don't have an urgent need to address the problem. This
is partly due to my other monitor working fine, and also because the
monitor does not malfunction frequently or for extended periods of
time (a couple hours of downtime over several weeks).
Another reason is that I'm not very knowledgeable or experienced on
this type of problem, so I'm ramping up quite a bit.
Yet another reason is that I'm a big proponent of measure twice, cut
once. From what I've read, opening the case isn't simple, and will
likely lead to blemishes. So I'd prefer to minimize the number of
times I have to open it, which can be accomplished by having some
confidence in the problem & solution. I understand that I won't know
or understand every detail. But I don't think knowledge will hurt,
and I'm not in a rush.
So given this list, I find it reasonable to perform some extra
diligence and learn a lot that I don't know, before digging in. I
realize some people have suggested that the caps are a common problem
w/ this monitor, but their problem doesn't seem to be the same as
mine. And I'd prefer to avoid unnecessary de-soldering & soldering,
given that I can actually make things worse. Given the symptoms of
the problem and all that I've learned from this group and the web, I'm
inclined to think the problem is the video board. But since I need to
open the case to get the video board's part & rev numbers, I'll have a
chance to inspect the caps before proceeding.
Thanks to everyone for your help, I really appreciate it. I'll post
back w/ my progress.
saber850
I opened the case and analyzed all the caps--none are bulging or
leaking/oozing.
Jeff Liebermann
wrote:
>> > >http://www.ccl-la.com/blog/index.php/samsung-214t-repair
>I opened the case and analyzed all the caps--none are bulging or
>leaking/oozing.
One small step... etc.
Look at the photos in:
<http://www.ccl-la.com/blog/index.php/samsung-214t-repair>
Do you see any bulging or leaks? Nope. Not all caps fail with
obvious physical evidence. That's where the ESR meter is used. You
can test the capacitors without removing them from the circuit.
Lacking that, just get some replacement caps, replace everything
listed in the article, and it should be back to working.
As for a better understanding of what's happening, it's difficult
enough to analyzer a circuit when all the parts are within normal
design limits. However, if you want to see what happens when you
insert a defective capacitor into the circuit, download a free copy of
LTSpice (formerly known as SwitcherCAD),
<http://www.linear.com/designtools/software/>
and buy a collection of SPICE switcher models:
<http://pagesperso-orange.fr/cbasso/Spice.htm>
<http://pagesperso-orange.fr/cbasso/Downloads/LTSpice/PWM%20Switch%20LTSpice.zip>
The author suggests you need the book to understand the models. I
agree.
Get the program working with a proper switching power supply. It
doesn't have to be exactly the same as the Samsung monitor. Then cram
in the equivalent of a bad capacitor, which would be a normal
capacitor, with the same capacitance value as on the label, but with
an added series resistance equal to about 2-5 times maximum ESR.
<http://members.ozemail.com.au/~bobpar/2003esrchart.txt>
<http://members.ozemail.com.au/~bobpar/graph1.gif>
<http://members.ozemail.com.au/~bobpar/graph2.gif>
<http://members.ozemail.com.au/~bobpar/graph3.gif>
A subtle hint is that with a switching power supply, the output
voltage almost never goes up when a component fails. It either goes
down, or massive amounts of high frequency ripple appears on the
output. How the rest of the LCD monitor responds to this is a bit of
a guess. Usually, it just shuts down, resulting in a black display.
Also, I forgot to caution you to *NOT* constantly power cycle the
monitor in an attempt to revive the circuit. It's bad enough having
the capacitors blow up. There's a chance that the associated
switching transistors will not appreciate the added load (which is
what's heating the capacitors) and blow up. For example, this loser
of a Dell monitor:
<http://www.ccl-la.com/blog/index.php/dell-e173fpb-17lcd-repair/>
usually takes out 6 xsistors, a diode, and anywhere between one and
eight electrolytics. I once tried to fix one, and didn't catch one of
the caps. Within a week, all 6 transistors were again blown.
Also, if you read the above instructions carefully, note that it
mentions resoldering the xformer leads. I do this whether it needs it
or not. What happens is that the xformers operate at about 40KHz(?).
Some of this 40KHz energy is transfered to the xformer leads,
resulting in cracked solder. It's very difficult to see without a
microscope. It was a problem with Tin-Lead solder but is really a
PITA with brittle ROHS Tin-Silver solder. The same thing can happen
at audio frequencies:
<http://www.clarkeaudio.com/nfinfo.htm>
Anyway, your next ordeal will be selecting the proper replacement
capacitors from the Digikey or Mouser online order pages. It's very
easy to pick the wrong part. Be careful, or ask for help. Also, buy
some spares. My prediction is that your matching monitor will soon
have the same problem.
saber850
> On Tue, 4 May 2010 20:15:46 -0700 (PDT), saber850 <saber...@yahoo.com>
> wrote:
>
> >> > >http://www.ccl-la.com/blog/index.php/samsung-214t-repair
> >I opened the case and analyzed all the caps--none are bulging or
> >leaking/oozing.
>
> One small step... etc.
>
> Look at the photos in:
> <http://www.ccl-la.com/blog/index.php/samsung-214t-repair>
> Do you see any bulging or leaks? Nope. Not all caps fail with
> obvious physical evidence. That's where the ESR meter is used. You
> can test the capacitors without removing them from the circuit.
> Lacking that, just get some replacement caps, replace everything
> listed in the article, and it should be back to working.
>
> As for a better understanding of what's happening, it's difficult
> enough to analyzer a circuit when all the parts are within normal
> design limits. However, if you want to see what happens when you
> insert a defective capacitor into the circuit, download a free copy of
> LTSpice (formerly known as SwitcherCAD),
> <http://www.linear.com/designtools/software/>
> and buy a collection of SPICE switcher models:
> <http://pagesperso-orange.fr/cbasso/Spice.htm>
> Skype: JeffLiebermann AE6KS 831-336-2558
Thanks. Is there a particular brand of caps which is considered the
best? From my reading, I should stay away from CapXon (which is what
the Samsung monitor uses).
Jeff Liebermann
wrote:
>Thanks. Is there a particular brand of caps which is considered the
>best? From my reading, I should stay away from CapXon (which is what
>the Samsung monitor uses).
Looking at my inventory, I've been using Panasonic-ECG, type A, Series
NHG, with 105C temperature ratings. For example, the Digikey part
number for 1000UF/16v is P5533-ND
<http://industrial.panasonic.com/www-data/pdf/ABA0000/ABA0000CE26.pdf>
<http://dkc3.digikey.com/PDF/US2010/P1643.pdf>
If you want to avoid the problem entirely, search for Polymer
Capacitors, which don't have any electrolyte. Fujitsu, UCC, and Oscon
make those.
<http://www.fpcap.jp/en/products/index.html>
I just tried to fix a Samsung Syncmaster 192N monitor. I replaced 6
assorted CapXon electrolytics but the monitor doesn't work. My ESR
meter is at home so I'll drag the pile home and report on the measured
ESR values. A bit of Googling seems to indicate the CapXon are junk.
More:
<http://pavel.kirkovsky.com/2009/03/samsung-syncmaster-204b-repair/>
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com je...@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Jeff Liebermann
wrote:
>I just tried to fix a Samsung Syncmaster 192N monitor. I replaced 6
>assorted CapXon electrolytics but the monitor doesn't work. My ESR
>meter is at home so I'll drag the pile home and report on the measured
>ESR values.
Hmmm... Weird and not according to my guesswork, as usual.
Value Max ESR Measured ESR
1000uF 25v 0.10 0.08
1000uF 25v 0.10 0.07
1000uF 10v 0.10 0.12
1000uF 10v 0.10 0.08
330uF 25v 0.30 0.10
330uF 25v 0.30 0.10
Max ESR from this chart:
<http://members.ozemail.com.au/~bobpar/2003esrchart.txt>
Out of 6 caps removed and tested, only one of them is somewhat bad. No
wonder replacing the caps didn't fix the monitor. Something else is
wrong. So much for the easy fix.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Dav.p.
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.
Dav.p.
sorry, i espected... i've made a jam.. the strange thing was: nobody has told to test 5v line..
saber850
Yes, I've been considering swapping one of the boards between the
monitors. This seems like the easiest way to narrow down the problem.
Dav.p.
saber850
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?
Jeff Liebermann
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.
Dav.p.
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.
saber850
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.
saber850
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.
Jeff Liebermann
<sabe...@yahoo.com> wrote:
>PCB Designation Farads (�F) 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
You probably do NOT need to replace the big 150uF/450V capacitor. It's
not the high voltage low ripple current capacitors that fail. It's the
low voltage, but high ripple current filter caps that get hot and blow
up.
>C107 47 50 105 11 24 5 5 667-ECA-1HHG470
>http://www.mouser.com/Search/ProductDetail.aspx?R=ECA-1HHG470virtualkey66720000virtualkey667-ECA-1HHG470
Tolerable. It's not a low ESR type, but it's low enough to work.
>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
It's low-ESR (although the data sheet doesn't clearly show this) so it
will work.
>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
Also low-ESR and good quality cap. No problems.
>C112 330 25 105 14 24 10 5 667-EEU-FC1E331
>http://www.mouser.com/Search/ProductDetail.aspx?R=EEU-FC1E331virtualkey66720000virtualkey667-EEU-FC1E331
Looks generally ok.
I'll leave it to you to determine if the case sizes and lead spacing
are the same as the originals. Neither is particularly critical as
there is usually plenty of room. One suggestion is to use the next
higher voltage rating capacitor. The 50v cap will probably remain
50v, but the 25v caps should be replaced with 35v caps. They last
longer, have a lower ESR, and aren't that much larger.
saber850
> On Mon, 10 May 2010 13:32:47 -0700 (PDT), saber850
>
> >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
>
> You probably do NOT need to replace the big 150uF/450V capacitor. It's
> not the high voltage low ripple current capacitors that fail. It's the
> low voltage, but high ripple current filter caps that get hot and blow
> up.
>
> >C107 47 50 105 11 24 5 5 667-ECA-1HHG470
>
> Tolerable. It's not a low ESR type, but it's low enough to work.
>
> >C301 680 25 105 17 22 10 5 667-EEU-FC1E681
> >C302 680 25 105 17 22 10 5 667-EEU-FC1E681
>
> It's low-ESR (although the data sheet doesn't clearly show this) so it
> will work.
>
> >C110 820 25 105 22 24 10 5 598-361R821M025EG0E
> >C111 820 25 105 22 24 10 5 598-361R821M025EG0E
>
> Also low-ESR and good quality cap. No problems.
>
> >C112 330 25 105 14 24 10 5 667-EEU-FC1E331
>
> Looks generally ok.
>
> I'll leave it to you to determine if the case sizes and lead spacing
> are the same as the originals. Neither is particularly critical as
> there is usually plenty of room. One suggestion is to use the next
> higher voltage rating capacitor. The 50v cap will probably remain
> 50v, but the 25v caps should be replaced with 35v caps. They last
> longer, have a lower ESR, and aren't that much larger.
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Skype: JeffLiebermann AE6KS 831-336-2558
Thanks for reviewing & the feedback. I'm glad I don't need to change
the large cap.
I'm looking for a cap w/ a lower ESR for the C107 cap (47uF, 50V). I
don't see 'ESR' in the data sheet. What do I look for? Would this
one be better:
http://www.mouser.com/ProductDetail/Panasonic/EEU-EB1H470S/?qs=sGAEpiMZZMtZ1n0r9vR22ZOBEZetCii%252b7xHyu04R92c%3d
?
Most of these caps were near, if not at, the physical size limit. All
of the 25V caps have <= 2mm of space to a neighboring component, and
in 2 cases, it's another cap (so only one could be bigger). So there
isn't much room for these (one will actually be a very tight fit as
is).
Jeff Liebermann
<sabe...@yahoo.com> wrote:
>I'm looking for a cap w/ a lower ESR for the C107 cap (47uF, 50V). I
>don't see 'ESR' in the data sheet. What do I look for?
If the ESR isn't specified, then look for loss tangent or dissipation
factor (tan sigma). Dissipation factor does NOT directly translate to
ESR, but it's proportional when comparing caps at the same frequency.
The lower number is better.
<http://en.wikipedia.org/wiki/Dissipation_factor>
ESR = DF / (Pi * freq * C)
You can calculate ESR, but there's a problem. The dissipation of the
dielectric varies with frequency where the ESR number specified is
only valid at the test frequency. When DF or loss tangents are
specified, it's sometimes at 120Hz, where the capacitor is intended
for a linear type AC power supply filter. When ESR is specified, it's
usually at 100KHz which implies that it's for a switching power
supply. The Panasonic EEU-FC series you included specifies ESR as
impedance at 100KHz. For comparison, a 47uF/50v Panasonic EEU-FC
series cap as below shows 0.6 ohms max ESR.
>Would this
>one be better:
>http://www.mouser.com/ProductDetail/Panasonic/EEU-EB1H470S/?qs=sGAEpiMZZMtZ1n0r9vR22ZOBEZetCii%252b7xHyu04R92c%3d
Well, for 47uf/50v the Panasonic EEU shows 0.15 DF.
The previous Chemicon KMQ series cap shows 0.12 DF.
I would call the Chemicon capacitor slightly better.
Unfortunately, the sanity check doesn't quite work. The ESR at 100KHz
grinds out to:
ESR = DF / (2Pi * freq * C)
ESR = 0.15 / (6.28 * 0.1*10^6 * 47*10^-6)
ESR = 0.15 / 29.8 = 0.0005
which is about 1000 times too small to be for real. When my brain
recovers from this cold or flu, I'll try to figure out what I've done
wrong. (I hate it when that happens).
>Most of these caps were near, if not at, the physical size limit. All
>of the 25V caps have <= 2mm of space to a neighboring component, and
>in 2 cases, it's another cap (so only one could be bigger). So there
>isn't much room for these (one will actually be a very tight fit as
>is).
Looking at the photos of the board, some of the caps look fairly
tight. I guess you should probably leave it at 25V.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
saber850
> On Mon, 10 May 2010 16:53:58 -0700 (PDT), saber850
>
> >I'm looking for a cap w/ a lower ESR for the C107 cap (47uF, 50V). I
> >don't see 'ESR' in the data sheet. What do I look for?
>
> If the ESR isn't specified, then look for loss tangent or dissipation
> factor (tan sigma). Dissipation factor does NOT directly translate to
> ESR, but it's proportional when comparing caps at the same frequency.
> The lower number is better.
> <http://en.wikipedia.org/wiki/Dissipation_factor>
> ESR = DF / (Pi * freq * C)
> You can calculate ESR, but there's a problem. The dissipation of the
> dielectric varies with frequency where the ESR number specified is
> only valid at the test frequency. When DF or loss tangents are
> specified, it's sometimes at 120Hz, where the capacitor is intended
> for a linear type AC power supply filter. When ESR is specified, it's
> usually at 100KHz which implies that it's for a switching power
> supply. The Panasonic EEU-FC series you included specifies ESR as
> impedance at 100KHz. For comparison, a 47uF/50v Panasonic EEU-FC
> series cap as below shows 0.6 ohms max ESR.
>
> >Would this
> >one be better:
>
> Well, for 47uf/50v the Panasonic EEU shows 0.15 DF.
> The previous Chemicon KMQ series cap shows 0.12 DF.
> I would call the Chemicon capacitor slightly better.
>
> Unfortunately, the sanity check doesn't quite work. The ESR at 100KHz
> grinds out to:
> ESR = DF / (2Pi * freq * C)
> ESR = 0.15 / (6.28 * 0.1*10^6 * 47*10^-6)
> ESR = 0.15 / 29.8 = 0.0005
> which is about 1000 times too small to be for real. When my brain
> recovers from this cold or flu, I'll try to figure out what I've done
> wrong. (I hate it when that happens).
>
> >Most of these caps were near, if not at, the physical size limit. All
> >of the 25V caps have <= 2mm of space to a neighboring component, and
> >in 2 cases, it's another cap (so only one could be bigger). So there
> >isn't much room for these (one will actually be a very tight fit as
> >is).
>
> Looking at the photos of the board, some of the caps look fairly
> tight. I guess you should probably leave it at 25V.
>
> --
> Jeff Liebermann je...@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Skype: JeffLiebermann AE6KS 831-336-2558
Thanks for all the info.
Which tool(s) should I consider getting to help w/ the desoldering?
I'm guessing there's something to help get the solder out of the PCB
hole. Braided copper? Solder sucker?
bz
news:16a07027-3ed3-420e...@37g2000yqm.googlegroups.com:
> On May 10, 5:42�pm, Jeff Liebermann <je...@cruzio.com> wrote:
>> On Mon, 10 May 2010 13:32:47 -0700 (PDT), saber850
>>
>> <saber...@yahoo.com> wrote:
>> >PCB Designation � � Farads (�F) � �Voltage (V) � � Temp (C
> ) � � � �Length (mm)
> tZ1n0r9vR22ZOBEZetCii%252b7xHyu04R92c%3d ?
>
> Most of these caps were near, if not at, the physical size limit. All
> of the 25V caps have <= 2mm of space to a neighboring component, and
> in 2 cases, it's another cap (so only one could be bigger). So there
> isn't much room for these (one will actually be a very tight fit as
> is).
>
ESR Equivalent Series Resistance
http://wiki.xtronics.com/index.php/Capacitors_and_ESR
ESR is usually NOT 'important' on new capacitors.
One 'common' failure mode for electrolytic capacitors in an increase in
ESR, especially in caps that have defective designs.
http://www.badcaps.net/pages.php?vid=4
--
bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
Jeff Liebermann
<sabe...@yahoo.com> wrote:
>Which tool(s) should I consider getting to help w/ the desoldering?
>I'm guessing there's something to help get the solder out of the PCB
>hole. Braided copper? Solder sucker?
Sigh. We're really down to the basics. You're probably dealing with
RoHS solder. That means an 850F tip and a temperature controlled
soldering iron. 750F will work, but takes a bit longer. I haven't
looked at cheap soldering irons for a long time, so I don't have a
specific recommendation. Note that if the soldering iron is rated
only in watts, not temperature, go find something else. It's probably
not temperature controlled.
I recently bought one of these conglomerations:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290434181031>
but haven't had a reason to use it yet. It looks big, clumsy, and has
a rather large tip, but looks useful for some things. I don't think
cleaning the pump is going to be fun while attached to a hot iron. We
shall see.
Some kind of vacuum solder sucker should work:
<http://www.parts-express.com/pe/showdetl.cfm?partnumber=370-030>
Radio Shack also carries these. Lots more on eBay. Solder braid
might also be handy, but not really necessary.
Most LCD power supply boards are single sided with no plated through
holes. Those are the easiest boards to work with. When I recently
replaced all the electrolytics on a Samsung LCD display (which didn't
fix the problem), I just heated up the leads, and pulled on the
capacitor case. No need for anything more elaborate. If the board
was double sided or multi-layer, which have plated through holes, the
solder sucker and solder wick would be needed.
If you haven't done much soldering, I suggest you practice with some
scrap boards before attacking.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeffrey D Angus
> Which tool(s) should I consider getting to help w/ the desoldering?
> I'm guessing there's something to help get the solder out of the PCB
> hole. Braided copper? Solder sucker?
Solder suckers seem best suited for vacuum tube sockets and
terminal strips. Solder Wick(tm) Seems best suited for lifting
traces.
I've had extremely good luck using one of these:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320523954535
Put the hole in the tip over the exposed lead, add a bit of
solder then when it all melts, push the button on the vacuum
and move the tool in a circular motion around the pin. Turn
the vacuum off after you've removed the tool from the lead.
Occasionally, I get a lead stuck in the hole, but a simple
chisel tip can get it free. Go back over, add solder and re-
vacuum the hole to get it empty afterwards.
The key to ANY soldering operation whether it is assembly or
desoldering is hot enough, fast and clean.
Of course, like the other Jeff I do this for a living, so
investing in the correct tools is money well spent.
Jeff
--
�Egotism is the anesthetic that dulls the pain of stupidity.�
Frank Leahy, Head coach, Notre Dame 1941-1954
Jeff Liebermann
<jan...@suddenlink.net> wrote:
>Solder suckers seem best suited for vacuum tube sockets and
>terminal strips. Solder Wick(tm) Seems best suited for lifting
>traces.
I just hate to agree with you, but you're right. Still, it is
possible to remove components with either device if you're careful.
However, for massive desoldering jobs, nothing beats a propane torch,
air compressor, and blow gun.
>I've had extremely good luck using one of these:
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320523954535
Retch. I suffered with one of those for about a year at a former
employer. About every 5 sucks, I had to clean the self clogging tip.
There were about 5 of them in the lab and all of them clogged exactly
the same way.
I switched to an overpriced Pace desoldering station and sucked
happily ever after.
<http://802.11junk.com/jeffl/crud/pace-desoldering-station.jpg>
Big and ugly really is better.
>Put the hole in the tip over the exposed lead, add a bit of
>solder then when it all melts, push the button on the vacuum
>and move the tool in a circular motion around the pin. Turn
>the vacuum off after you've removed the tool from the lead.
Circular motion? Won't that tear up the pad? If I don't get all the
solder in the first suck, I add some more solder and/or flux, get the
joint hot, and suck again. Flux is the key as you can't suck dross.
Moving the tip around the joint just seems to make a mess and more
dross.
>Occasionally, I get a lead stuck in the hole, but a simple
>chisel tip can get it free. Go back over, add solder and re-
>vacuum the hole to get it empty afterwards.
Yep.
>The key to ANY soldering operation whether it is assembly or
>desoldering is hot enough, fast and clean.
Yep, yep, yep.
>Of course, like the other Jeff I do this for a living, so
>investing in the correct tools is money well spent.
You call this living? I'm still agonizing over buying a hot air SMT
desoldering station. I was borrowing one for a while and became
addicted.
The other Jeff.
(I haven't mailed the Symbol junk yet. Sorry.)
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jeffrey D Angus
> <jan...@suddenlink.net> wrote:
>> Put the hole in the tip over the exposed lead, add a bit of
>> solder then when it all melts, push the button on the vacuum
>> and move the tool in a circular motion around the pin. Turn
>> the vacuum off after you've removed the tool from the lead.
>
> Circular motion? Won't that tear up the pad? If I don't get all the
> solder in the first suck, I add some more solder and/or flux, get the
> joint hot, and suck again. Flux is the key as you can't suck dross.
> Moving the tip around the joint just seems to make a mess and more
> dross.
I like to think of it as "circling the drain". Obviously
you don't press down on the pad, but I've found that doing
this circular motion makes all the difference in the world
sucking up enough solder to get an empty hole and exposed
lead.
> The other Jeff.
> (I haven't mailed the Symbol junk yet. Sorry.)
No rush.
Dav.p.
> holes. Those are the easiest boards to work with. When I recently
..and don't have a big ground area, for me can even work a poor 25W iron.. maybe
but depends on how big the board, to be sure start with a 50W one that
comes much useful for other works like recapping pc mainboards.. i say only to save
some money..
saber850
So the "working" monitor stopped working today w/ the same symptoms.
The only difference is that it has remained in this malfunctioning
state all day--the longest I've ever experienced. I can't help but
wonder if there's some truth to the theory that this is contagious.
Fortunately, I ordered 2x the caps a couple days ago. So hopefully
the problem is in fact the caps and I'll have both fixed soon.
Jeff Liebermann
<sabe...@yahoo.com> wrote:
>So the "working" monitor stopped working today w/ the same symptoms.
I warned you. Unfortunately, this one good guess does not make up for
all my other screwups.
>The only difference is that it has remained in this malfunctioning
>state all day--the longest I've ever experienced. I can't help but
>wonder if there's some truth to the theory that this is contagious.
This is the way rumors and religions are started.
>Fortunately, I ordered 2x the caps a couple days ago. So hopefully
>the problem is in fact the caps and I'll have both fixed soon.
Good move by planning ahead. What else can go wrong.... Well, work on
one monitor at a time, so that you have the other board as a sample
for which way to insert the capacitors, and where the connectors and
screws are located. It should be easy (famous last assumptions).
Mike Tomlinson
s.com>, saber850 <sabe...@yahoo.com> writes
>Fortunately, I ordered 2x the caps a couple days ago. So hopefully
>the problem is in fact the caps and I'll have both fixed soon.
It'd be interesting to hear how you got on.
--
(\__/)
(='.'=) Bunny's thinking about giving Windows 7
(")_(") a go despite what he's said about it...
ads...@wheeloyum.com
> In article <6b0a157b-e045-40eb-a7a9-cee3092a7...@h39g2000yqn.googlegroup
> s.com>, saber850 <saber...@yahoo.com> writes
>
> >Fortunately, I ordered 2x the caps a couple days ago. So hopefully
> >the problem is in fact the caps and I'll have both fixed soon.
>
> It'd be interesting to hear how you got on.
>
> --
> (\__/)
> (='.'=) Bunny's thinking about giving Windows 7
> (")_(") a go despite what he's said about it...
Absolutely! I intend on posting back with my next steps.
At this point, I'm still waiting for the parts (currently expected to
arrive tomorrow). I'll say I'm not thrilled to have paid >$8 to ship
a 0.4lb package which takes 5 business days to arrive. Perhaps I'm
spoiled by NewEgg's ship time & prices.
Fortunately, my monitors seem to be playing tag-team on functioning
correctly, so I can still function at this point.
saber850
I just completed soldering all the new caps to one of the boards! For
desoldering, I found it easier to simply heat each lead and gently
pull the cap out. The braided copper didn't really help, perhaps
because the pins are so small.
The good news is that the monitor functions fine (I thought I may have
messed up one of the caps). The unfortunate news is that only time
will tell if the problem is really solved.
I will post back with the status after a couple days. If all goes
well, I'll repeat the procedure on the other board.
Thank you all for your help thus far!
Dav.p.
what do you mean for 'working', them still had power boards swapped?
A monitor can't contaminate anything, it's a stupid thought..
maybe your monitors are produced same day as them has been bopught same day
and caps are equal and fails near same month or week.
saber850
Before and after I had swapped the power boards, only one of the two
monitors worked--and it contained the same power board each time.
Yes, both monitors were bought at the same time, and used roughly
equally. But one monitor started failing over 18 months ago, while
the other just started this month.
saber850
Bad news: the monitor w/ the new caps exhibited the same problem when
I first powered it on this morning. Ugh...
Dav.p.
Yes, both monitors were bought at the same time, and used roughly
equally. But one monitor started failing over 18 months ago, while
the other just started this month.
OK, the contamination doesn't exists then ...
i'm sorry for your bad news.. i would to think to monitoring
the pow.supply outputs and then evaluate if is a power board problem and
which part of it, it is useful to know if want to buy an used or new board or
continue to repair . If i'm not wrong the 12v line powers the inverter that by the
video seems to work well, there is a 5v and nothing more or a 3,3v,
test them, you can also supply 5v from another p.s.u. to have a verify. If 5v is stable
there is maybe a transistor that powers the panel, it makes the on/off function
for st.by mode, i have i Benq with this failed. you can test it, or test the supply pin to the
panel, u need the datasheet of the panel for pinout, it is possible to make
a bypass of this to supply the panel like i did for test.