Dumpsterdive TV repair - Page 1
Forum section: electronics / repair

author: KrisBendix
author_rank: Contributor
timestamp: December 17, 2016, 09:45:49 pm
content: Hi.Someone has decided to get rid of a TV. Seems to be in decent shape. Even remote is clan and shiny.Plugged it in, red LED turned on. LED does blink when trying to turn on, but TV itself is showing no life.Have been watching enough EEVblog on YouTube to know to check the caps. (Photo) Those three on the right has bulge. One had some brown crunchy stuff on it.I haven't really done any repairs like this. Just want to make sure I haven't missed anything. Could there be anything else to watch out for? And any advice when doing actual repair?

author: wraper
author_rank: Unknown
timestamp: December 17, 2016, 09:50:17 pm
content: Also replace 2 other black electrolytic capacitors on secondary side and small green cap on primary side. Use only LOW ESR types as replacement, regular capacitors won't survive more than a few months. And don't buy capacitors from China (ebay, aliexpress, DX), most of them are counterfeits.

author: Gyro
author_rank: Super Contributor
timestamp: December 17, 2016, 10:23:07 pm
content: It looks as if you've found yourself a nice TV there with a much better than even chance of fixing it.As wraper says, use decent low ESR branded (eg. Panasonic) 105'C capacitors from a distributor. You haven't got your country flag set so we don't know where you are to be able to advise. Hopefully you can use Farnell, digikey etc.I would also change the little startup cap on the primary side (C21 I think) it's too small to have a vent but it lives in a warm place and will tend to dry out. This can cause failure to start up at low temperatures. It's cheap and worth changing while you have the board out anyway.It's a single sided board so you should have no difficulty removing the old caps with a handheld solder sucker. Make sure that the main reservoir cap (C20) is discharged (by checking with a meter) before doing anything. Obviously double check capacitor polarities before powering back up.The other important step, you've already covered - take a photo before you start.P.S. Don't be surprised that there will be surface mount components on the back (for the two backlight inverters anyway).

author: KhronX
author_rank: Frequent Contributor
timestamp: December 17, 2016, 11:30:45 pm
content: Well, there's at least one (legit) exception re: getting caps from eBayhttp://stores.ebay.com/PC-MotherBoard-Capacitors-Store?_rdc=1I first came across recommendations for that on the badcaps.net forums, a few years ago. I've also bought several handfuls of caps on a few occasions.Surprisingly fast shipping (a week or so, definitely less than two) to Europe.Quote from: wraper on December 17, 2016, 09:50:17 pm

author: wraper
author_rank: Unknown
timestamp: December 17, 2016, 11:45:29 pm
content: Quote from: Gyro on December 17, 2016, 10:23:07 pmThat is the green cap I suggested to change. But it isn't a startup cap really. It's a smoothing capacitor for PWM controller power. Although it provides enough stored energy at startup (charged through the high value resistor with a small current), before rectified voltage from the transformer winding provides the supply voltage for PWM controller (charging the very same capactor), once PSU is running.

author: Fisher77
author_rank: Regular Contributor
timestamp: December 18, 2016, 03:56:34 am
content: Check all the fuses you see on the board as well. They will be labeled F1, F2, etc. There may just be the one I see on the bottom left corner, or several., or there could be several.

author: KrisBendix
author_rank: Contributor
timestamp: December 18, 2016, 05:24:23 pm
content: Ok.What if I salvage some caps from a PC PSU or some other device to test first? Would suck if I order new ones, wait a week and then it doesn't work.Heres is photo of other side. Is it common to have soldered ground wire? A bit annoying... cant take it out without soldering it off.

author: retiredcaps
author_rank: Super Contributor
timestamp: December 18, 2016, 06:16:47 pm
content: Quote from: KrisBendix on December 18, 2016, 05:24:23 pmThat is what I do with found or given bad equipment that have obviously bad capacitors. I put in used capacitors for testing and if and only if the item works, then I replace all the capacitors with high quality low ESR brands like Panasonic, Nichicon, United Chemicon or Rubycon.You never know if the TV has a cracked screen or some other physical damage that you can't see until you fix the power supply.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: December 21, 2016, 01:13:14 am
content: And please,post whether you succeeded/failed and some description of your work. I always like to hear success stories and also failures as a "lessons learned" scenario.Show a pic of the TV actually running if you get it fixed. (Or a pic pf you tossing into dumpster again...)PEACE====>T

author: BradC
author_rank: Super Contributor
timestamp: December 21, 2016, 01:55:34 am
content: Quote from: KrisBendix on December 18, 2016, 05:24:23 pmYeah. What I do is grab any low ESR cap with at least 50% of the required capacity and exceeding the voltage rating and just tack it across the back of the PCB over the existing cap. If it's the cap at fault that always gives it enough oomph to get things going and prove the viability of repair.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 21, 2016, 10:23:18 am
content: Technically, this is bothMains power supply with the inverter section included. See that multi-pin connector right next to the bloated caps? Yeah, that's the power going off to the mainboard.If you mean the TO-220-packaged part bolted to that aluminum heatsink, odds are way better that's "just" the double-diode rectifier.I sincerely doubt they would've bothered with synchronous rectification in something like thinsQuote from: aquamon on December 21, 2016, 10:21:15 am

author: wraper
author_rank: Unknown
timestamp: December 21, 2016, 10:28:52 am
content: Quote from: aquamon on December 21, 2016, 10:21:15 amThat is not a FET, just a dual Schottky diode, chances that it failed are very slim.

author: wraper
author_rank: Unknown
timestamp: December 21, 2016, 10:39:40 am
content: Quote from: aquamon on December 21, 2016, 10:31:14 amFirst of all, no one suggested changing the largest cap on the primary side. It doesn't fail often and is the most expensive among them. Why? Because spending additional $1 on the parts will avoid a high probability trouble of repairing it again in a year.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2016, 10:55:25 am
content: Quote from: aquamon on December 21, 2016, 10:31:14 amWhy would there be a FET there??? It's on the secondary side of the SMPS, not the primary. It's a rectifier.It's a simple (and typical) case of the secondary side reservoir caps having gone high ESR and vented. It happens to most consumer gear given time.Why change the other (cheap) capacitors (not the big mains reservoir which almost never fails)?... Because the OP is far more likely to damage connectors etc. (particularly the backight ones) if he goes back and pulls it all apart again later. Common sense!QuoteHuh?

author: KrisBendix
author_rank: Contributor
timestamp: December 21, 2016, 02:24:06 pm
content: Success!Didn't have to change anything else, just those 3 caps. Now only thing that is left is to get proper low ESR ones. May be change all of them while at it. No matter how expensive they are, it is still nothing for a decent TV.Don't know about that DVD player, tho. Don't have any DVDs to test. Peoples still using them?Btw, what's with the FET? Didn't see anything there apart from warped thermal pad or whatever it is.

author: wraper
author_rank: Unknown
timestamp: December 21, 2016, 03:04:31 pm
content: Quote from: KrisBendix on December 21, 2016, 02:24:06 pmWhere are you located? If in Riga, you could get Samxon caps at Salvats, which are decent enough. Or Ormixhttp://ormix.lv/lv/catalog/category/id/G0240113Elite are good enough too, they also have some Hitano and Samxon. They also have Samwha which will do either, just don't buy WB series. They also ship in Latvia at a few EUR cost.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 21, 2016, 03:12:18 pm
content: I could also recommend "egekecu" -http://stores.ebay.com/id=298040899?ssPageName=STRK:MEFSXS:MESST&_trksid=p2053788.m1543.l2653First found out about that on the badcaps.net forums a few years ago. Ordered a few times myself, and shipping (despite being free and from the Far East) was surprisingly quick, around a week or just a bit over thatI really wouldn't (want to) recommend anything less than Japanese electrolytics, though. Elite and Hitano are in the (large) "replace on sight" section, in my book, and so is Samwha, as well as Samyoung. Samxon are above average, but avoid the GF (and probably GT?) series, those are known to fail.That is, unless you want to repeat this exercise a couple years down the road

author: wraper
author_rank: Unknown
timestamp: December 21, 2016, 03:25:21 pm
content: Quote from: KhronX on December 21, 2016, 03:12:18 pmAbout Elite, I never heard anything failing except EB series on the motherboards (people tend to say crap, but don't provide any examples). And have EL series running in one of the recapped ATX PSU for about 8 years, I think. Samxon GT series were never failing, and they are long life series, GF failed a lot, but they are fixed as for now AFAIK. Of Samwha, only WB series were really unreliable, WL are pretty robust. If we remember the past sins, Japanese nichicon made a lot of HM, HN crap at certain point of time, nippon Chemi-con made failing KZG and KZJ. And please mention at least one example of failed Hitano.

author: KhronX
author_rank: Frequent Contributor
timestamp: December 21, 2016, 03:45:42 pm
content: One failed Hitano was the first filter cap on the 3.3v rail in a TC Electronic StudioKonnekt 48 i bought in 2014, if memory serves. The unit kept "tripping up" during the boot sequence. After replacing that (470u / 10v) with a Rubycon YXG (1000u / 6.3v), the thing booted up right away. I sold that on eBay soon after that, and haven't heard from it since (no news is good news)There's at least one other case in a similar unit, the same capacitor, that someone else had issues with. I recall advising them in PM's on the badcaps.net forum.Elites, i've seen crapped out in LCD inverters, most likely in computer screens - can't remember if in TV's as well.Yes, i know about the '06-'07 HM/HN debacle in Dell desktops, and i've grown wary / skeptical of KZG's. I don't think Elna or Panasonic have had any "lemons" though, if memory serves. I think i've read of some failed Rubycon MBZ's some time ago, but never seen any myself.

author: mariush
author_rank: Super Contributor
timestamp: December 21, 2016, 06:19:23 pm
content: And if you can't find some proper capacitors locally, I can mail you some capacitors and you can pay a few euro for them (and the shipping costs) through paypal or something like that. Probably less than 5 euro in total.I have Panasonic FM and FR series and United Chemi Con / Nichicon capacitors in various capacity/voltage ratings in my personal stock , ordered from Farnell and Digikey, and it's not a big deal to put them in a box and mail them to you.But if you're interested, the soonest would probably be after Christmas.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2016, 07:19:42 pm
content: Hi aquamon,After seeing your reply in the CRT repair... thread I began to suspect that that might be the case.In many cases these days, repairs are far easier to diagnose that what you are used to, even without schematics.. Power supply circuitry has become much more 'mundane' and standardised, the primary side high voltage areas have become much smaller and segregated (making most fault-finding safer), with very few, if any, adjustments to make. It has become much more of an 'eyeball' the board for bulged caps etc. on the low voltage supply rails than systematic tracing. It's has become more about built in obsolescence, you can be pretty sure that at least 50% of failures are immediately down to capacitor failure rather than semicondictor.Being smaller (but higher stressed) caps are much cheaper to just replace in bulk while the board is out rather than testing each one (apart from the 'big' primary side ones which tends to be low stressed). My concern is always much more about the amount of effort to get to something, the fragile nature of interconnects and connectors these days with small number of mating cycles. I spent a fair proportion of my career designing high volume consumer gear (set-top-boxes and digital TVs) and even with attention to detail, cost and available space makes this almost inevitable.Sorry, for my reply at least, if you felt 'put down'. It's a shame that you no longer repair consumer equipment (for a living?). Repar of modern items could be quite profitable, (though much less interesting) depending strongly on local conditions. Consumers in too many countries assume that if it breaks out of warranty (even within sometimes), it's an excuse to throw it away and buy a shiny new one. Very sad. I don't know what consumer habits are like in Belize.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2016, 07:43:57 pm
content: You have better eyesight than I do! I can't make out the part numbersI can see one so8 pkg on the primary side of the smps section, I assume a PWM switching controller (IC1), driving the primary side switching FET (TO220 pkg). There's also an 8 pin FET package driving each of the backlight inverter transformers. The only cap (other than the main reservoir) that I can see on the primary side is the small green one which smooths the bias supply to the PWM IC. I can't see any FET associated with the blown secondary side caps.

author: wraper
author_rank: Unknown
timestamp: December 22, 2016, 03:32:39 am
content: Quote from: aquamon on December 21, 2016, 06:24:54 pmAnd this seems to be the source of your weird suggestions. CRT repair practices do not apply to LCD at all, maybe primary side of SMPS but no more than that. You were suggesting that regular capacitors are fine. Yeah fine, if you don't mind repairing again in 1-3 months and cleaning the board from leaked electrolyte.

author: Monkeh
author_rank: Super Contributor
timestamp: December 22, 2016, 04:22:29 am
content: Quote from: aquamon on December 21, 2016, 07:26:43 pmYes, there's a controller (that is not the switching FET) down there for the backlight drivers. Yes, there will be two dual MOSFET packages, one for each transformer. However, they do not have electrolytic output caps and the CCFL driver does not work anything like any circuit you're used to from a CRT.The CCFL driver FETs do not typically go wrong unless something goes wrong with the tubes. This is all a 'regular PS' in this application (except CCFL's dead and buried these days).

author: Gyro
author_rank: Super Contributor
timestamp: December 22, 2016, 01:20:20 pm
content: Quote from: aquamon on December 22, 2016, 11:38:31 am@aquamon:I have already appologised if you felt thatmyreply made you feel bad. I genuinely can't identifywhichFET you were talking about, can you be more specific please.QuoteI've had a long career in design but am sure there are many things still to learn, I can't immediately identify what lesson there is related to this particular item though. Can you clarify?

author: Gyro
author_rank: Super Contributor
timestamp: December 22, 2016, 11:06:18 pm
content: @aquamon:Quote from: aquamon on December 21, 2016, 10:21:15 amEDIT:QuoteThat's the FET I was asking you about!I already said there was a FET driving each of the backlight inverter transformers:QuoteAgain, I was asking you where the FET associated with the failed capacitors was! I couldn't see it, still can't.

author: Monkeh
author_rank: Super Contributor
timestamp: December 23, 2016, 12:10:36 am
content: Quote from: aquamon on December 23, 2016, 12:08:56 amWe all know what a MOSFET looks like.

author: aquamon
author_rank: Newbie
timestamp: December 23, 2016, 12:12:27 am
content: My God...

author: wraper
author_rank: Unknown
timestamp: December 23, 2016, 12:20:10 am
content: Quote from: aquamon on December 23, 2016, 12:12:27 amTotally agreeAnd now how dual Schottky diode looks likehttp://docs-europe.electrocomponents.com/webdocs/0ed1/0900766b80ed1e39.pdf

author: Gyro
author_rank: Super Contributor
timestamp: December 23, 2016, 11:40:54 am
content: Quote from: aquamon on December 23, 2016, 12:08:56 amYes, I know what a FET looks like too, I've designed in plenty. In fact I can see three of them on the board, two SO8 pkg and a TO220 pkg, just not the one you "don't see" now.If you can't see it either and you can't explain what function it would be performing in the circuit if it was there, then there really isn't any more to be said, is there?

author: Gyro
author_rank: Super Contributor
timestamp: December 23, 2016, 06:16:21 pm
content: I've already indicated that there's no more to be said, by me anyway.

author: Gyro
author_rank: Super Contributor
timestamp: December 23, 2016, 06:50:16 pm
content: WTF are you talking about???You come to this thread, which was already providing the OP with all the help he needed, with your:Quote... and then keep going on about some mythical non-existent FET, even posting a link to what a FET looks like FFSI see you are also trolling the Westinghouse... thread, and the DL209L equivalent threads too!You are being reported, trolls are not welcome or knowingly fed here!

author: wraper
author_rank: Unknown
timestamp: December 23, 2016, 06:52:30 pm
content: Quote from: aquamon on December 23, 2016, 06:38:24 pmJust LOL.First you were seeing and suggesting replacing the FET besides swollen capacitors. When proven there is none, suddenly your memory became short of that. Now keeping your point by saying there are FETs in other places on this board. What a freaking discovery, CCFL inverter which is using MOSFETS. There are 3 MOSFETS on this board (two of them 2x in one package), none of them in the secondary side of the PSU, where swollen caps are located.

author: Simon
author_rank: Unknown
timestamp: December 23, 2016, 08:06:22 pm
content: Now the topic is closed!!!