bad caps on samsung lcd display

[linux-works]

I found a 22" lcd monitor thrown away in the dumpster, at work.  hmm, maybe its a simple fix.  people throw stuff out and never give it a 2nd thought.

so, I took it home and searched online for any obvious problems.  it seems this model (Samsung 225BW) is nothing BUT trouble; I bet every single one has blown caps JUST past warranty time ;(  stupid samsung!  I'll never buy a samsung monitor after seeing how many people had blown caps in theirs.  it shows that samsung does not care about users and cares only about profits, making their products with KNOWN bad caps.  sheesh!  they'll last about as long as warranty period and then self-destruct after that.  STUPID SAMSUNG!

here's photos of the psu board and the bad caps that I replaced:





its now better than new, after the replacment.  and now I'll have 2 monitors at my desk, at work.  "how did you get a 2nd display?".  "well, I fished a broken one out of the trash and fixed it!  that gives me the right to now use it".  lol

what you see, for the fault, is that it powers up, shows a screen for a short bit and then the screen goes blank or dim.  power off and on again and the cycle repeats.

this was the first net search hit I found when searching:

http://www.ccl-la.com/blog/index.php/repairing-the-samsung-225bw-22-monitor/

it was clear to me that I needed caps.  that's all it needed, and that totally fixed the problem.

I'm not sure how bad other display vendors are; I have some dell displays that are more than 5 yrs old and still working fine.  but many of the samsungs in our test lab seem to have this display problem.  seems to indicate that samsung is a brand that should be avoided for lcd displays (maybe other things too, if this is their corporate mentality).

[robimarko]

Yeah they are known to use Capxon caps that are real garbage.
Before Capxon Samsung was using Samwha which are like light years ahead of Capxon altough they are not really top of the line.
Before my transistor tester arrived I recently replaced mains filtering cap and one that was filtering I think 135V dc rail in old Samsung CRT TV,and when I measured capacity and ESR they were in perfect condition,they were even gold series,and Samsung used those gold series ones for all important filtering.

And in the end it looks like the crappy FJL6920 transistor died

[retiredcaps]

My favourite monitor is a Samsung 226BW that I got for free.  It has the same obviously blown caps.

[Skimask]

Done a dozen or so of the Samsung 22-26" LCD monitors in the past year or so.  Same story every time.  Crap Capicon Caps (say that three times fast).
Got a decent stash of them in the bins just waiting for the next dozen or so.
And I make a fair amount of $$$ for each repair as well.

[robimarko]

Done a dozen or so of the Samsung 22-26" LCD monitors in the past year or so.  Same story every time.  Crap Capicon Caps (say that three times fast).
Got a decent stash of them in the bins just waiting for the next dozen or so.
And I make a fair amount of $$$ for each repair as well.

Its easy to fix them,but to get them here in Croatia it is damn hard.
Especially for free or really cheap

[GreyWoolfe]

That's a shame to hear.  I have a SyncMaster 940BW 19" wide screen that I have had for about 4 years now, I think.  I like the color on it very much.  It is my 2nd display monitor and it has served me well with no issues.  Sounds like Samsung got boards with the same Crapxon caps just like Dell did.

[linux-works]

I guess I'll stock a few 'sets' since the monitors in our lab are GOING to go bad, sooner rather than later.

[Prime73]

Well, I did the same repair on 19" display I had laying around for parts. It was working after the repair however 2 month later same problem:


Must be something else is going on on the power supply? or I just got bad quality caps? (yes, I bought these caps on ebay)

[wraper]

Well, I did the same repair on 19" display I had laying around for parts. It was working after the repair however 2 month later same problem:
Must be working else is going on on the power supply? or I just got bad quality caps? (yes, I bought these caps on ebay)

Because they are obvious fakes with wrong went on the top.

[Prime73]

Well, I did the same repair on 19" display I had laying around for parts. It was working after the repair however 2 month later same problem:
Must be working else is going on on the power supply? or I just got bad quality caps? (yes, I bought these caps on ebay)

Because they are obvious fakes with wrong went on the top.

ok fair enough. but how do you know these are fakes? more general question - how to tell/measure apart a fake cap from a genuine one?

[Skimask]

Keep in mind crappy caps aren't always the issue.
Take the case of an office that's warm in the first place, with the back of the monitor sitting on a desk in a west facing window.  Back of the monitor gets hot, can only get so much heat out of there from convection.  That'll kill any cap over time.
Or the idiots that put the exhaust fan from the PC blowing directly on the back of the monitor itself.
People, in general, are stupid...which is why I stay in business.

[retiredcaps]

ok fair enough. but how do you know these are fakes? more general question - how to tell/measure apart a fake cap from a genuine one?

Buy them from reputable distributors like digikey, mouser, etc.  Capacitors from ebay are 98% counterfeit.  Dealextreme has also sold fake Sanyo capacitors.

The "recommended" brands are Nichicon, Panasonic, United Chemi-con and Rubycon.  Each vendor has their own vent (top) style and bung (bottom).  The datasheets for each capacitor will show you a picture of what the vents/bungs should look like.

As mentioned, your Sanyo's are obviously fakes because they have an X vent.

[retiredcaps]

In addition, using the wrong series of caps will also cause them to fail prematurely.

In a SMPS, you will likely need low ESR caps.  Caps like Panasonic FM or FR series.

PS. Replacing only the obviously bulged capacitors and thinking it is "repaired" is another newbie mistake.

[wraper]

ok fair enough. but how do you know these are fakes? more general question - how to tell/measure apart a fake cap from a genuine one?

Measuring won't tell anything in many cases. Maybe if there is a huge capacitance/ESR inconsistency in one batch. One of the most obvious is wrong vent, maybe wrong marking, sleeve color. Capacitors should be bought only at reputable places as on ebay/aliexpress chances to get crap are close to 90-95%

[Kostas]

Sometimes sleeve colour is ok, but sleeve placement is random between capacitors of the same "batch". I had a batch from ebay, too good to be true price, where most of the capacitors had the sleeve either too high or too low on the barrel. They also had wrong vent type (X instead of K).

[What_NZ]

In addition, using the wrong series of caps will also cause them to fail prematurely.

In a SMPS, you will likely need low ESR caps.  Caps like Panasonic FM or FR series.

PS. Replacing only the obviously bulged capacitors and thinking it is "repaired" is another newbie mistake.

The Capacitor Bible - http://industrial.panasonic.com/jp/i/29880/2T_E/2T_E.pdf
or the cut down version http://industrial.panasonic.com/www-data/pdf/ABA0000/ABA0000PE285.pdf

[lpc32]

How closely do you need to match the specs of the original caps? Are power supply caps practically the only thing that breaks?

[wraper]

How closely do you need to match the specs of the original caps? Are power supply caps practically the only thing that breaks?

Generally just watch that ESR is around that of original or lower and max ripple current is the same or higher. If the replacement is from top manufacturer, it wouldn't be too bad even if parameters are a bit worse, just because they don't embellish them as crap brands.
They are not only things what breaks but a very common fault. Especially if psu is made around 2003-2008.

[retiredcaps]

Are power supply caps practically the only thing that breaks?

Having spent significant time on badcaps.net helping others fix their broken lcd monitors, the answer is no.

Other things that go bad are the bridge rectifier (usually after some power outage/storm), fuse, voltage regulators on the main/logic board, corrupt eeproms, bad ccfls, poor solder joints and shorted transistors.

[fluxcapacitor]

there are some sellers on ebay that i trust,ive never had any fakes from them .

http://stores.ebay.co.uk/PC-MotherBoard-Capacitors-Store

[lpc32]

Will a much lower ESR than the original caps destabilize the power supply output?

[David Hess]

Will a much lower ESR than the original caps destabilize the power supply output?

It is possible but also unlikely you will be able to lower the ESR enough to do this unless you change the capacitor type.

[lpc32]

You mean solid polymer instead of wet?

[David Hess]

You mean solid polymer instead of wet?

That could be enough to do it but it will depend on design of the switching regulator and how much phase margin remains with the very low ESR capacitor.  Usually this problem shows up when an aluminum electrolytic or solid tantalum capacitor at the output of a low dropout regulator is replaced with a large value ceramic capacitor.

It is easy enough to test with an oscilloscope by watching the output during a sharp load change.  In extreme cases the output will oscillate.

[lpc32]

What are the expected side effects of higher ESR, and of lower ripple current rating?

[David Hess]

What are the expected side effects of higher ESR, and of lower ripple current rating?

Higher ESR results in higher output ripple but counter intuitively it also usually increases the phase margin making the regulator more stable. 

Higher ESR also results in higher temperature operation because at a given ripple current, more power will be dissipated by the capacitor.  The higher temperature lowers the operating life.  This is reflected in the ripple current rating which will be lower and is the reason why low a ESR is associated with a high ripple current rating.

It is sometimes necessary to use multiple capacitors in parallel to achieve a high ripple current rating.  Multiple small capacitors are often better than fewer large ones because their greater surface area for a given volume allows greater heat dissipation capability.

[lpc32]

Thanks.

[HighVoltage]

One of the best Samsung monitors from the early flat screen days is the SyncMaster 214T
They sold for almost $2000 in those days.
And the beauty is that you can get them for almost free, when they are broken.
And each and every time, the problem was in the ESR of the Caps

It is unreal to me, that a company like Samsung would deploy bad caps for such a long time
It seems we are talking now of a period from 8 to 10 years of bad caps in SyncMaster screens

[linux-works]

the more I talk to folks who have dealt with samsung, the more I hear this thing coming up again and again.

samsung designs things so that they last JUST as long as the warranty and no more.  almost to a science.

I like samsung ssd's but I'm going to try to avoid that company for all other things if I can help it.  I see a trend, here, in the corporate culture.  I've heard and read too much about samsung for it to be a one-off problem.

[SeanB]

2 Samsung 24 inch monitors, bought new and with a 5 year warranty. Both failed about 2 weeks out of warranty. One was left running 24/7/365 and the other was switched off ( with a real power switch on the front of the unit, no soft switch here) at the end of each day. In both units the line output transistor was shorted, due to the line output transformer breaking down. The LOPT was no longer available as a spare part ( though I could actually get the 24 inch CRT complete with scan coils as a spare and they had stock of it) as it had been discontinued 4 years ago. Apparently they simply gave you a new monitor of the same or next bigger size if they failed under warranty and it was not a dead CRT. Burns were not covered, and these large CRT's were very easy to burn if you left the brightness high with a static image.

[P90]

I just fixed an LG monitor that had 3 bad CapXon caps. $3 and up and running again! woohooo! 

[Bud]

it seems this model (Samsung 225BW) is nothing BUT trouble;

Hmmm.... The one I am using typing this message is I think 7 years old, still working fine