EEVblog #347 - Bad Cap LCD Monitor Repair - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: September 07, 2012, 11:38:56 pm
content: Dave.

author: mariush
author_rank: Super Contributor
timestamp: September 07, 2012, 11:41:16 pm
content: No surprise there.Capxon is very well known manufacturer for making capacitors that don't handle heat. They all die eventually.ps. that one is probably from Mexico or somewhere that's NOT South Korea - the ones they assemble in Korea are usually made with Samwha capacitors - just as bad as Capxon imho.ps2. watched to the end... those S.I capacitors are worse than CapXon ... I don't think they'd last more than a few months if the monitors run several hours a day. I'd recommend replacing them as soon as possible with some United Chemi Con / Nichicon / Rubycon capacitors.

author: nicknails
author_rank: Regular Contributor
timestamp: September 08, 2012, 12:05:55 am
content: I would have just replaced them all since I was in there anyway. No point in taking it apart twice!

author: Rerouter
author_rank: Super Contributor
timestamp: September 08, 2012, 12:06:25 am
content: always fun getting near freebies just because of a blown cap or 2, even to the extreme of them failing in 30 year old test equiptment, still its sometimes hard to justify the cost of replacing all of them with top quality capsalso whats people opinion on not only getting higher temperature /life capacitors but also higher voltage for replacement?

author: EEVblog
author_rank: Unknown
timestamp: September 08, 2012, 12:08:18 am
content: Quote from: nicknails on September 08, 2012, 12:05:55 amNot when I don't have good brand ones to replace with.I just needed them up and running for the show on Tues.I wasn't about to pay $7ea for no-name 400V caps.Dave.

author: David_AVD
author_rank: Super Contributor
timestamp: September 08, 2012, 12:09:21 am
content: Well done Dave. A nice simple repair but satisfying because it only cost you a few bucks in parts.The main filter cap is rarely faulty. Almost always the only issue is the low voltage side.

author: EEMarc
author_rank: Regular Contributor
timestamp: September 08, 2012, 12:38:32 am
content: I wonder who got the big bonus for that decision...

author: jaycee
author_rank: Regular Contributor
timestamp: September 08, 2012, 12:49:35 am
content: Seen this so, so many times in all sorts of things...The line side is usually OK because it doesn't have to withstand a lot of ripple current, it only sees 100-120Hz from rectified mains. On the output though, they're seeing kilohertz from the SMPS output. This is where low ESR is a must.CrapXon ones just obviously aren't - i'd go so far as to accuse CrapXon of LYING on their spec sheets. They can't withstand the ripple current and they blow their guts. If you're lucky, a well designed power supply sees the failing caps as shorts on the outputs, and turns off. Similar story with pretty much all the other Chinese brand capacitors. The big names - Nichicon, Rubycon, Nippon Chemicon, BC Components, Panasonic etc... no problem.If you're unlucky you end up with major damage. I have a monitor where popped CrapXon capacitors unfortunately also took out the MOSFETs and control IC in the backlight circuit. Similarly I have an LCD TV where capacitor failure in the PSU seems to have damaged something on the mainboard, as even after replacing the caps and verifying the supply itself is working correctly, there's no sign of life.

author: Psi
author_rank: Super Contributor
timestamp: September 08, 2012, 01:01:00 am
content: Yeah, the mains filter cap is only 50hz and has bugger all ripple current compared to the switchmode caps which are probably 200khz with massive ripple current.It's the ripple current which kills them.When a manufacture decides to use dodgy caps they often put more caps in parallel and have a bigger total capacity than the design required, just to get a lower esr and higher ripple current.So when replacing crap 0.5A ripple current caps with awesome 6A ripple current polymer electrolytic caps lowering the capacity value a bit is ok.Never lower the temp rating or voltage though.Also,I was waiting for Dave to either short that big 450V cap with a screwdriver or accidentally touch the pcb and get zapped. Since it didn't power up the cap was probably still charged.When fixing appliances with bad caps its far far better to get it done before the device fully dies.Normally you start to get ripple and noise on the screen image as the caps start to fail. So you get some warning.Often, if the caps get so bad that the device wont even turn on, the switching mosfets short out and die, which then shorts the gate to vcc and often takes out the gate driver and a few other things.So it can be lots components to repair if you leave it too late.Luckily in this case they look to have designed the lcd so bad caps dont blow up other stuff.Editdamn, jaycee bet me to it for most of that.

author: JoannaK
author_rank: Frequent Contributor
timestamp: September 08, 2012, 01:12:05 am
content: Dave, you mentioned the ESR meter you have.. Would be nice to see it on video and to get some examples of good/bad caps with it..

author: Fir3Chi3f
author_rank: Contributor
timestamp: September 08, 2012, 01:15:10 am
content: Had mentioned elsewhere that I made a tutorial for cap replacements, so thought I would link ya to it!http://www.overclock.net/t/1076808/fir3chi3fs-new-indepth-capacitor-replacement-monitor-repair-tutorialAnother great video! I feel that most of what I know about electrical engineering has been learned from you Dave!

author: samgab
author_rank: Frequent Contributor
timestamp: September 08, 2012, 02:17:50 am
content: You asked about service menu over on the youtube page.I found this, written in Chinglish:http://www.fastrepairguide.com/monitor-and-lcd-monitor-problem-solutions/login-factory-service-mode-samsung-lcd-mo-2.htmlWorth a try, you may be able to find out how many hours those monitors have done, and maybe report back to us interested punters?

author: gxti
author_rank: Frequent Contributor
timestamp: September 08, 2012, 03:49:53 am
content: Definitely something about that particular generation of SyncMaster LCDs. I bought a smaller version for my mom for Christmas a few years back, and it failed maybe a year ago. Recapped with UCC 105degC caps, no problems since! Thanks, dickhead from the purchasing department, for giving me that rewarding experience.

author: David_AVD
author_rank: Super Contributor
timestamp: September 08, 2012, 04:38:06 am
content: Better than the Benq's though. The caps go bad, chopper IC (or FET?) goes bang and they're often a write-off.

author: SeanB
author_rank: Super Contributor
timestamp: September 08, 2012, 06:37:20 am
content: Samgab, thanks for the service menu guide. Mine has done 6700 odd hours, and been turned on 4700 times, with 9 power cycles........ Not bad for a 2 year old display.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 08, 2012, 07:22:32 am
content: When replacing caps in a PSU you should also replace the low-voltage one on the mains side - this is for the startup supply and a common cause of failure as on initial startup the supply comes through a high value resistor, and even a small amount of leakage on this cap can prevent the PSU starting.

author: hans
author_rank: Super Contributor
timestamp: September 08, 2012, 07:44:00 am
content: I fixed 2 Samsung 940BF last summer that had a faulty backlight driver. I think it's around the same age, the construction is very similar (annoying clips on the front size, annoying mouning of the shielding - the 940BF was even more annoying that it had the PCB boards on the backshield plate, and some cover plates to protect the HV outlets, isolation paper on the back).In my case I had 2 monitors from the same batch, same age, similar use time (well , 1 failed first - had more hours on it, used the second one, which failed 2 months later).And ofcourse it were those bloody caps! Same capacitance, same voltages, probably same PSU design. I only replaced the dodgy caps with quality low ESR 105C ones from Farnell.Can be a quick job though, if you're familiar with the model. The first one took longer (going to farnell etc), the second one 15 minutes.

author: tom66
author_rank: Super Contributor
timestamp: September 08, 2012, 07:51:27 am
content: Brand name caps aren't expensive from DigiKey.I have however seen the line cap fail on several monitors, none belonging to me (all on badcaps.net.) Samxon and Capxon line caps tend to fail with gunk coming out of one or the other terminal. On a monitor with PFC, this usually results in a dead switching MOSFET, diode, and blown fuse, all because they tried to save a few cents... I hate Samsung products now, they have nice pictures when working but they never last, unless you fix them by replacing the caps and other insufficient components they cut back on.

author: poptones
author_rank: Frequent Contributor
timestamp: September 08, 2012, 07:52:03 am
content: Back in the day when it was still common to find large surplus lots on ebay, I madeso much moneybuying large lots of decent quality electros and reselling them in motherboard sized batches.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 08, 2012, 09:02:13 am
content: As a result of so many bad caps, there are full replacement kits available for computer motherboards. You just specify the board model number and often there is a bag o parts packed just for you.

author: IanJ
author_rank: Unknown
timestamp: September 08, 2012, 09:22:13 am
content: Quote from: Ed.Kloonk on September 08, 2012, 09:02:13 amSame here in the UK........there is an abundance of cap kits available for SKY set top boxes.Lost count of the amount of boxes I've fixed for friends n family................but the thing is, every time they come out with a new model of box the same issues remain. It's a conspiracy, they design the boxes to last a couple of years only I reckon.Ian.

author: tom66
author_rank: Super Contributor
timestamp: September 08, 2012, 09:34:30 am
content: Quote from: IanJ on September 08, 2012, 09:22:13 amThe Samsung and Thomson boxes are rubbish and have bad cap issues.The older (and possibly newer) Amstrad boxes are very well built. I took one apart - full of Rubycons!

author: amyk
author_rank: Super Contributor
timestamp: September 08, 2012, 11:04:07 am
content: Possibly interesting trivia: That Genesis SoC contains an embedded 80186 processor.Rather surprising when I found that out (several years ago), as most monitor SoCs are based on the 6502 or 8051.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 08, 2012, 11:17:00 am
content: Quote from: amyk on September 08, 2012, 11:04:07 amThis is interesting.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 08, 2012, 11:19:59 am
content: Quote from: tom66 on September 08, 2012, 09:34:30 amI had either a samsung or HP monitor, sorry I really can't remember which, that had a known fault of a poor sodder joint around one of the components in the psu. I googled the problem, found it was quite documented. Opened it up and sure enough, bad joint. A little sodder and I was away.

author: IanJ
author_rank: Unknown
timestamp: September 08, 2012, 11:51:19 am
content: Quote from: tom66 on September 08, 2012, 09:34:30 amI have one of the very original boxes when SKY HD first came out (Thomson box I presume)...........still going strong after all these years. Have always meant to get around to opening it up and seeing what brand caps it has.PS. It's either ON or on STANDBY 24/7.Ian.

author: tom66
author_rank: Super Contributor
timestamp: September 08, 2012, 12:52:07 pm
content: Quote from: IanJ on September 08, 2012, 11:51:19 amI have a spare Thomson skydigibox (not HD, or sky+) which has two bad caps. It has worked with them for at least 6 months but has some problems tuning into certain channels. I have got to get around to replacing them but we're using the HD box now.

author: cheepokleebo
author_rank: Newbie
timestamp: September 08, 2012, 06:25:34 pm
content: The rule is simple: Google the product - the chances of someone having the exact same problem as you are high. Case in point - the second monitor having the leaky cap in the exact same position. Fixed my Philips DVD player in 15 minutes - one bulging 1000uF was replaced by 2 470uF caps and a gob of silicone bathtub sealer to hold them in place (very ugly). Three years later it still works.

author: madires
author_rank: Super Contributor
timestamp: September 08, 2012, 08:08:50 pm
content: That's why I always keep a good stack of low ESR caps (common values) of well known vendors in the drawer ;-)

author: SeanB
author_rank: Super Contributor
timestamp: September 08, 2012, 08:47:28 pm
content: RS SSM in many cases is 5, so i do tend to have some always, or i will nick them off a scrap board for a quick check. Helps before ordering to see if it in dying has not taken other parts with it as a farewell gesture.

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 08, 2012, 09:22:15 pm
content: As a repair tech I can attest that the high ESR causes regulation problems, forcing the output voltage higher, til the caps vent. Some PSU's have a zener diode across one or more output filter caps so the zener will short first and protect components downstream. Generally this forces the entire switcher to shut down, but sometimes the switching device will also die.The power supply unit in these Samsung's is a vendor part Samsung gets from someone else. Their home LCD TV's have has many problems in this area. Samsung has signed consent decrees to repair these at no cost even several years after the warranty expiration. A good portion of my income comes from these jobs.

author: FenderBender
author_rank: Super Contributor
timestamp: September 08, 2012, 11:35:56 pm
content: Quote from: David_AVD on September 08, 2012, 12:09:21 amI think that that cap is the PFC correction cap, which don't encounter too much stress..which isn't to say that it couldn't go bad, but it's less likely. The output caps are subject to a lot of high frequency ripple, so sure those of course matter.Yeah I was curious why you (Dave) needed to have it up and working so quickly, but it makes sense now. Electronex!As you've said, those monitors are probably otherwise very good. Might be worth to recap them with good Japanese caps if you get the chance. If you don't think you'll need them, you can probably get $50 out of them at least.

author: David_AVD
author_rank: Super Contributor
timestamp: September 09, 2012, 12:49:10 am
content: Quote from: FenderBender on September 08, 2012, 11:35:56 pmNo, I was referring to the reservoir capacitor which is has the rectified mains (340VDC) on it.

author: T4P
author_rank: Super Contributor
timestamp: September 09, 2012, 05:01:43 am
content: Pretty much most companies that we know not be to "reliable" or any consumer product NOT from japan will have CapXon caps ... still work better than some taiwanese caps from the P4 days i think?

author: TriodeTiger
author_rank: Regular Contributor
timestamp: September 09, 2012, 05:08:51 am
content: Or the other perspective - build them to run until the next line comes out, or the cycle when businesses tend to order new updated PCs. Why not have the monitors go too?I had a syncmaster once, a 24 inch CRT meant for medical work if I recall - they designed 'em well back then - and businesses would keep them if they didn't take up half a desk and leave a permanent depression in them.

author: Rerouter
author_rank: Super Contributor
timestamp: September 09, 2012, 05:12:03 am
content: well to add to the drone, today i had to go and replace one of the main filter caps in my modem, though it was branded ST, though oddly enough the ones of the same make that lived near the sodding hot processor where still in fine nick (really need an esr meter)for reference to anyone else, it was a SS4200 modem and was the 6.3V 1000uF cap, the rail its on sees spikes near 7V rather commonly, seems they thought they would group 2 caps rather than buy a seperate higher voltage one, or pay for 2 higher voltage ones,

author: SeanB
author_rank: Super Contributor
timestamp: September 09, 2012, 05:46:29 am
content: The 24 inch Syncmaster CRT units had a very well known failure mode, the line output transformer would die, either quietly short or spectacularly explosively, at around the 5 year mark, just out of warranty. Had one pop exactly 1 week after the warranty expired, to the day. The transformer is not available as a spare part ( discontinued 3 years before with the end of the range) so it was tossed. The way the agents did warranty claims in the last 2 years was to give you a new monitor of the same or bigger size if not available, they did not have the spares any more to fix them.

author: G7PSK
author_rank: Super Contributor
timestamp: September 09, 2012, 08:19:42 am
content: The First time I ever experienced catastrophic electrolytic failure was on an answer phone in the 1981, It exploded with such force that it displaced the bridge rectifier and voltage regulator, there was no switch mode on that machine just a mains transformer, but it was not even running of the mains as this machine was in a remote farm where there was no mains so the unit had been rigged to run from 24 volt battery when the generators were turned off, as it was I was sitting with my back to the machine when it exploded, I repaired the machine and a couple of years later it did the same thing again, The capacitor was 35 volt rated if I remember correctly the second time it happened I replaced with a 60 volt cap and it never went again, but the first time it blew it sounded like a shotgun being fired right behind me.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 09, 2012, 08:42:59 am
content: Quote from: G7PSK on September 09, 2012, 08:19:42 amHow do you know what that sounds like?

author: notsob
author_rank: Frequent Contributor
timestamp: September 09, 2012, 08:50:57 am
content: Ask his father in law

author: FenderBender
author_rank: Super Contributor
timestamp: September 09, 2012, 03:56:46 pm
content: Quote from: AcHmed99 on September 09, 2012, 01:39:25 amAlright then, my mistake.Oh darn, I have an Acer monitor...I've had it since 2007...Fingers crossed...

author: T4P
author_rank: Super Contributor
timestamp: September 09, 2012, 04:22:12 pm
content: I hope yours doesn't blow up like one of my Samsung monitors did, the fuse popped so hard and there were sparks!Turns out the transformer shorted out!

author: Slobodan
author_rank: Regular Contributor
timestamp: September 09, 2012, 04:36:48 pm
content: I have replaced electrolytic caps in ATX power supply few months ago with Jamicon brand. Are they any good?

author: T4P
author_rank: Super Contributor
timestamp: September 09, 2012, 04:47:19 pm
content: Quote from: Slobodan on September 09, 2012, 04:36:48 pmNA brand, but not really any good.

author: Slobodan
author_rank: Regular Contributor
timestamp: September 09, 2012, 05:01:40 pm
content: Quote from: T4P on September 09, 2012, 04:47:19 pmIf you could just tell me what does "NA" stands for?

author: mariush
author_rank: Super Contributor
timestamp: September 09, 2012, 05:14:46 pm
content: Probably North America.Jamicon is OK for general purpose capacitors... like remote controls, toy cars, radios, CRT TVs.. but not for places that heat up a lot like back of lcd monitors or for circuits that require low ESR due to high switching frequencies.They're not Low ESR, can't handle as much ripple as the Japanese caps... and overal their technical specifications don't match those of Japanese brands.So probably not, I don't think they'd last long in a power supply. But it depends on how much air flow you have there, how sensitive your pc components are to ripple and other things.

author: Slobodan
author_rank: Regular Contributor
timestamp: September 09, 2012, 05:27:16 pm
content: Thanks. I remember that I chose those beause they were the same specs (or a little bit better) as the ones I replaced. They are 105 C and 1.1 Arms ripple current rated. The power suply is "DTK Computers" brand, and as far as I remember, the "original" caps (output filter caps) were some chinese brand and not even "low esr".Edit: "Original" capacitors are Fuhjyyu TNR. Jamicon is better than them, isn't it?

author: FenderBender
author_rank: Super Contributor
timestamp: September 09, 2012, 07:44:17 pm
content: Wellanythingis better than Fuhjyyu. I still would not trust Jamicon in any medium to high stress environment. Honestly, the price difference between a Japanese brand and something like Jamicon is so small, just get the Japanese brand. Sure they probably don't sell them at the local electronics store, but it's usually worth it to wait 2-3 days for Farnell, Digikey, or Mouser to ship you a few.

author: Slobodan
author_rank: Regular Contributor
timestamp: September 09, 2012, 08:10:41 pm
content: Thanks. I will order better quality capacitors from Farnell then.

author: Slobodan
author_rank: Regular Contributor
timestamp: September 10, 2012, 11:56:49 am
content: Well what can I do, I was curious, so I couldn't help it... I have opened my SAMSUNG SyncMaster 920N (it had 6700 working hours) and I have found that all electrolytic caps where fine (at least not bulged), and they are Samxon GF(M). So my question, again, is are these caps any good and should I replace them with good quality ones, as a precaution?http://www.lckdanny.com/samxon/

author: G7PSK
author_rank: Super Contributor
timestamp: September 10, 2012, 12:03:18 pm
content: Quote from: Ed.Kloonk on September 09, 2012, 08:42:59 amWell being a former range officer and a shooter mostly clay's these days there has been occasions when I have been very near some firing a shot gun sometimes behind me such as when in a line and I fire to my left and the guy to my right fires forward or such like.

author: T4P
author_rank: Super Contributor
timestamp: September 10, 2012, 02:37:30 pm
content: Quote from: Slobodan on September 10, 2012, 11:56:49 amNo good, definitely not . i remember somebody here saying SamXon is samsung's capacitor manufacturing

author: Slobodan
author_rank: Regular Contributor
timestamp: September 10, 2012, 02:59:55 pm
content: OK, thanks. I have ordered some Panasonic, Rubycon, United Chemi-Con and Nichicon one's (for LCD monitor and for ATX power supply).

author: mariush
author_rank: Super Contributor
timestamp: September 10, 2012, 03:55:21 pm
content: QuoteNo, they're not. SamXon generally are OK, but the very low ESR ones (GF in particular) go bad often.So you're probably just lucky that it lasted so long, or you live somewhere colder than usual/you have air conditioning set at cold in the house.Samsung made capacitors and they were Samsung:but at some point they sold the business or rebranded their capacitor business as SamwhaSamsung likes to use Samwha in a lot of their monitors, because Samwha is also South Korean like them. There was rumor is Samwha bought manufacturing plants from Samsung or something like that, but Samsung advertises Samwha directly on their site so I guess they have something to do with them.At some point, some series from SamYoung and Samwha were OEM capacitors made by Evercon... who was previously known as Sacon who were previously known as GSC... (Sacon FZ series are guaranteed to blow up or die, the nightmare of video cards).GSC also did Capsun, Comet, Lelon OC-CON... seehttp://capacitor.web.fc2.com/special2.htmlAt some point, SamYoung also had some partnership with United ChemiCon - that's why their logo was very similar to United Chemi Con's. Later on there was some argument/lawsuit and scrapped the logo:SamYoung by UCC:SamYoung by them:

author: Slobodan
author_rank: Regular Contributor
timestamp: September 10, 2012, 04:08:35 pm
content: Thanks for the information.

author: tom66
author_rank: Super Contributor
timestamp: September 10, 2012, 06:03:18 pm
content: Samsung have had a major issue with Samwha capacitors going bad after a couple of years in their LCD TVs/Monitors (and to a lesser extent their plasmas, though they tend to use the worse C(r)apXons in them, which also go bad.)LG also used them and got bitten by the bad caps (the first LCD TV I fixed was an LG 42LC46 with four bad Samwha WB caps) but not half as bad as Samsung as LG mostly used Samxon and SamYoung which for some series are good, others they are average or poor.It seems that Samwha had a major issue with the reliability of the WB and XC series. It seems to have been more of an inconsistency in manufacturing (like the overfilled Nichicon HM/HN's) as I have seen some WB last ages, others die in two years. The caps generally bulge when fail, I've not seen any that just dry up and die.Older Panasonic plasmas were very well built with excellent caps but I've just seen inside the newer ones - full of crappy Aishi and Taicon caps!!

author: T4P
author_rank: Super Contributor
timestamp: September 10, 2012, 07:16:51 pm
content: Right, thanks for clarifying. Poor memory of mine

author: samgab
author_rank: Frequent Contributor
timestamp: September 10, 2012, 07:56:27 pm
content: Quote from: Slobodan on September 10, 2012, 11:56:49 amYes, but despite what was said above, have you ever heard the expression "If it ain't broke, don't fix it"? Wait until you have a problem, then fix it.But on the other hand, there is also the saying "An ounce of prevention is worth a pound of cure" - Benjamin Franklin... So, your choice.

author: mariush
author_rank: Super Contributor
timestamp: September 10, 2012, 08:23:43 pm
content: I'm actually on the other side on this one... you should definitely fix it if you have the money to get quality capacitors and are skilled with a soldering iron.Bad capacitors can do quite a lot of damage to a power supply - it can make transistors oscillate or overheat and die (and sometimes you have a hard time finding replacement ones), diodes can short... some power supply have zener diodes acting as a sort of protection so capacitors going bad can cause these to trigger and turn the power supply off.Dave would know a lot more about this and it really sucks Dave didn't have enough time to give some explanations in plain English (or better put Australian) about the role of the capacitors in power supplies.On my own monitor on my desk, Samsung T240... the backlight starts to ever so slightly flicker, most likely due to capacitors giving bad power to the inverters or the cfl lamps getting old. it's about 2 years old but I certainly won't wait until it dies completely to repair it, it's often more difficult to fix them.

author: tom66
author_rank: Super Contributor
timestamp: September 11, 2012, 06:21:24 am
content: A common issue on Samsung LCD TVs is for bad caps to corrupt the EEPROM (set won't boot if this is the case) which can be tricky to fix.

author: T4P
author_rank: Super Contributor
timestamp: September 11, 2012, 06:35:34 pm
content: My Samsung ... LA22A450C1 TV that was a free gift i use everyday as my monitor, first 2 years used quite a bit but i use it permanently since last year.Hasn't gone awry but when it does i'm pretty darn sure it isn't that bad as normal consumer equipment of the time, this was in 2008 where Samsung was considerably cheap and decent now it's just expensive and nastyAnd the TV that was first purchased in question only broke once on the 3rd year just BEFORE warranty, the entire LCD went bust.

author: JoannaK
author_rank: Frequent Contributor
timestamp: September 11, 2012, 08:58:35 pm
content: I'm not sure if I should blame or thank Dave... due this video I decided to order an ESR meter. Thankfully it's not a big investment and I do have hope that it'll pays back on some future repairs/hacks.

author: Pat Pending
author_rank: Regular Contributor
timestamp: September 11, 2012, 09:05:47 pm
content: Does anyone know why the connection to the driver PCB to the LCD panel is by individual wires as opposed to a ribbon or flex cable?

author: tom66
author_rank: Super Contributor
timestamp: September 11, 2012, 09:07:10 pm
content: They sometimes do it with ribbon flex too, my 24" 1080p monitor uses a flat flex ribbon but it's kind of rare. It probably depends on the signal speed, EMI requirements, cost, etc...

author: Pentium100
author_rank: Frequent Contributor
timestamp: September 11, 2012, 11:26:01 pm
content: Quote from: Pat Pending on September 11, 2012, 09:05:47 pmThe cable seemed to use twisted pairs. While it is possible to have a twisted pair ribbon cable (I have a couple U320 SCSI cables that are like this), individual pairs are probably cheaper.As for caps - the ones that operate on the line frequency rarely go bad, unless they were made in late 80ss early 90s in the USSR. Those dry up and look completely normal but are essentially an open circuit.

author: ebidk
author_rank: Newbie
timestamp: September 12, 2012, 05:47:59 am
content: There's a problem with the Samsung SyncMaster 226BW where the backlight flashes.The power supply board looks very similar if it's not actually the same one. It can be fixed by replacing 3 capacitors.I have apost about it, which also link to a post with pictures of the rest of the boards in the 226BW.

author: SeanB
author_rank: Super Contributor
timestamp: September 12, 2012, 05:46:23 pm
content: I have a new victim/patient from work today. 30 odd kilos of 24 inch Samsung Syncmaster CRT, DOA, but with the power light on. Will be stripped sometime when space and time is available to see what is wrong, or what died and stopped it working. Good life for this one, made in 2002, and on 24/7 for the most part since then, though there was a DPMS power switch that did work for the most part.

author: Chipguy
author_rank: Unknown
timestamp: September 12, 2012, 07:53:01 pm
content: Yay Dave you are so luckyIn both cases the little green fuse was still ok. I had to replace them when mine failed as well.Good work !Chipguy

author: sonic
author_rank: Regular Contributor
timestamp: September 12, 2012, 09:59:49 pm
content: On my SyncMaster 244T, the green power LED was only dimly lit. I also successfully replaced all caps (excluding the 400 V one) on the PSU in it and other gear. I documented my ESR readingshere.Quote from: mikeselectricstuff on September 08, 2012, 07:22:32 amThis happened to me with the Jentec JTA0302F-E PSU that D-Link liked to use often.

author: dda
author_rank: Contributor
timestamp: September 13, 2012, 03:37:59 am
content: So, what is a low-esr value (ohms) compared to a not low? What kind of esr should i be looking at when im capacitor shopping?

author: mariush
author_rank: Super Contributor
timestamp: September 13, 2012, 04:02:35 am
content: Look in the datasheets for impedance below 0.04-0.06 ohm .... the capacitors with such value are low esr... ultra low esr i'd say would be 0.006-0.025 ohm - but be careful, as some circuits are designed to have some impedance, they won't like ultra low esr capacitors.Also look for the amount of ripple current they can handle - you want the value listed at 100kHz or anything above 10 kHz at a positive temperature ... if the datasheet only lists 120Hz or some low frequency, that's a sign those capacitors are not suitable for switching power supplies or other high frequency stuff. You want a value as high as possible.Last, look at the temperature rating, make sure they're 105c and ideally 2000 hours or better - lcd monitors can be quite hot in the back, so you want capacitors that can handle heat well.Oh... and don't forget to check the diameter and height - you want capacitors that fit in the room you have and not touch the lid and cause shorts or other bad things.For a 470uF 25v like Dave has in the monitor, you're looking for something with at least 800mA ripple and about 0.04-0.06 ohm impedance - something like Panasonic FC series would fit this and would be the lowest from Panasonic I'd use.For a 820uF 25v, something around 1200mA and 0.04 or lower impedance would work.Good brands and series for monitor fixing would be (imho, i may be wrong with some, not really an expert in this):Panasonic FM, FR, FC (in worst case),Nichicon HM, HD, HE,United Chemi Con KZE, KY , LXZ ,Rubycon ZL, ZLH, YXF , YXJ etc

author: JoannaK
author_rank: Frequent Contributor
timestamp: September 13, 2012, 04:51:19 am
content: Quote from: sonic on September 12, 2012, 09:59:49 pmI think I'll need to check couple chepish Digibox power supplies nearby.. Those have the most mysterious startup-problems.

author: stryker
author_rank: Regular Contributor
timestamp: September 20, 2012, 11:38:43 am
content: Thanks for the inspiration and explanation Dave. I found an LCD monitor on top of the dumpsters under our building last week, by luck a Samsung with no power but a different model. Found the caps in that part of the power supply board were in some cases swollen, but not yet leaking. Took the punt and replaced them and can report a successful first dumpster dive!Bad news is while I've 'made' a monitor for $5, it has a fault in the LCD that shows a full height vertical single pixel line near the right side. Nevermind. Was a good exercise and it's something I wouldn't have tried without seeing your vid.Please keep em coming !Geoff

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: September 20, 2012, 10:23:47 pm
content: stryker stryker stryker stryker!

author: Unknown
author_rank: Unknown
timestamp: September 24, 2012, 01:15:48 pm
content: I just fixed my Samsung by replacing the bulged Capxon. I replaced it with a smaller sized cap but with the same Farad and Voltage. I then saw some posts that says different sizes probably mean different ESR (whatever that is).The monitor now works, but is it ok if I just leave it like that without checking the ESR? Assuming the ESR doesn't match, can somebody explain to me in plain English the consequences of a mismatched ESR?Thanks guys.

author: sonic
author_rank: Regular Contributor
timestamp: September 24, 2012, 01:31:23 pm
content: Quote from: bongiovi on September 24, 2012, 01:15:48 pmThe whole point of these caps is to filter ripple current. If theequivalent series resistance (ESR)is too high or it can't cope with the ripple current, the ripple current won't vanish but instead heat up the cap, which will in turn increase the ESR - the start of a positve feedback loop. It will then either fail prematurely by vomiting its guts (the electrolyte) through the vent holes on the top or bottom or explode if the vent holes don't break after the internal pressure has increased enough. Either case might cause secondary damage.So compare the ESR of your cap according to your datasheet tomy measurementsand replace it with a low ESR one if the ESR of your's is higher.Out of convenience, and because I also wasn't completely sure about all these parameters, I bought a kit fromLCDalternatives(also available viaAmazon).

author: T4P
author_rank: Super Contributor
timestamp: September 24, 2012, 07:10:37 pm
content: Quote from: bongiovi on September 24, 2012, 01:15:48 pmTaller caps, skinny caps = Low ESR Shorter, fatter caps = Normal

author: Cranky
author_rank: Newbie
timestamp: May 23, 2014, 12:02:39 pm
content: I am currently using 2 LG Flatron L246WH 24" monitors I repaired in the same way.They had 2 X 3300uF caps that had gone bad. Replaced with 3 X 2200uF (there was a spare spot on the board).They are still going after about 18 months or so.

author: TMM
author_rank: Frequent Contributor
timestamp: May 23, 2014, 05:08:58 pm
content: Quote from: T4P on September 24, 2012, 07:10:37 pmI can't say i have noticed that. If there is any 'rule of thumb' that is vaguely valid it would be that the physically larger the cap (regardless of aspect ratio), the lower the ESR. Even that doesn't always hold true. Panasonic FM series have very low ESR and they are fatter, shorter and smaller than most.edit:holy thread dig batman.

author: MrLostsoul
author_rank: Newbie
timestamp: November 16, 2017, 04:03:58 am
content: I have a question. I don't have all the caps in hand. When I got the monitor, it didn't turn on at all. I replaced two caps I had already in hand. Now the led power lights come on the monitor. But after a few seconds, the power light goes off and when that happens, it makes a sizzle/zip sounds before the led turns off.I think I just need to replace more caps. I would like to get your opinion. I have a Hanns-G HZ251HPB.

author: John Heath
author_rank: Frequent Contributor
timestamp: November 16, 2017, 07:10:15 am
content: I am writing to you on a Hannspree TV / computer monitor. You have my sympathy as you will not find remote control codes for this puppy let alone a diagram. They appear to be a flash in the pan company that has disappeared into the abyss. Most of the time you can google the model # and someone will have had the problem and found a solution. Not with a Hannspree as there are too few of them out there.The LEDs work for a while then stop , hmmm . I think your first guess is right for my 2 cents , more flat caps. As you have already looked your remaining flat caps do not have the classic bubble top. Step 2 use a ISR meter on the caps to see if you can sniff it out that way. And lets not forget any burnt looking resistors. 90 % of a LCD screen is low level electronics so it will seldom fail if not disturbed. This leaves only power supply issues of filter caps , resistors and such. Let it go for a while , sleep on it. You get up in the morning and you know where the problem is. The mind has an odd way of sorting things out while we sleep.

author: MrLostsoul
author_rank: Newbie
timestamp: November 19, 2017, 01:37:59 pm
content: Ok, I changed 2 caps. The led turns on then off then back on then off, and so forth. I'll check resisters too. Thank you - John Heath.Does anyone have a recommendation on where to buy caps? I've used ebay in the past, and that's fine. But I'd be interested in a source/supplier who I can ask questions. If there a friendly vendor online somewhere?

author: flumeboy
author_rank: Newbie
timestamp: March 12, 2019, 03:04:40 pm
content: Hi Dave - thanks for the video on re-capping these monitorsQuestion - when you encounter old capacitors that have leaked on your board, how do you recommend cleaning the board without damaging components?Cheers,

author: vk3em
author_rank: Contributor
timestamp: March 14, 2023, 11:31:33 am
content: For those like me who just watched the video and did a repair, please note that your capacitors may not visually look faulty.In my Asus VW222U, I had no visual leaking or bulging of capacitors, but after replacing them, the monitor worked perfectly.Unfortunately I was in a rush, so I ended up at Jaycar and the Samxon low ESR type, but if it gets me a few more years from this monitor (security cameras) I'll be happy for the $6 spent.