Author Topic: Dumpsterdive TV repair  (Read 9128 times)

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Offline KrisBendix

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Dumpsterdive TV repair
« on: December 17, 2016, 09:45:49 pm »
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?
 

Online wraper

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Re: Dumpsterdive TV repair
« Reply #1 on: December 17, 2016, 09:50:17 pm »
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.
 
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Online Gyro

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Re: Dumpsterdive TV repair
« Reply #2 on: December 17, 2016, 10:23:07 pm »
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).
« Last Edit: December 17, 2016, 10:31:50 pm by Gyro »
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Offline KhronX

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Re: Dumpsterdive TV repair
« Reply #3 on: December 17, 2016, 11:30:45 pm »
Well, there's at least one (legit) exception re: getting caps from eBay :)

http://stores.ebay.com/PC-MotherBoard-Capacitors-Store?_rdc=1

I 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.

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.
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Online wraper

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Re: Dumpsterdive TV repair
« Reply #4 on: December 17, 2016, 11:45:29 pm »
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.
That 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.
« Last Edit: December 17, 2016, 11:55:50 pm by wraper »
 

Offline Fisher77

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Re: Dumpsterdive TV repair
« Reply #5 on: December 18, 2016, 03:56:34 am »
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.
 

Offline KrisBendix

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Re: Dumpsterdive TV repair
« Reply #6 on: December 18, 2016, 05:24:23 pm »
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.  ;D
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.

 

Offline retiredcaps

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Re: Dumpsterdive TV repair
« Reply #7 on: December 18, 2016, 06:16:47 pm »
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.
That 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.
 

Offline tpowell1830

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Re: Dumpsterdive TV repair
« Reply #8 on: December 21, 2016, 01:13:14 am »
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...  :horse:)

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Online BradC

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Re: Dumpsterdive TV repair
« Reply #9 on: December 21, 2016, 01:55:34 am »
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.  ;D

Yeah. 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.
 

Offline KhronX

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Re: Dumpsterdive TV repair
« Reply #10 on: December 21, 2016, 10:23:18 am »
Technically, this is both ;) Mains 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 thins :)

Whoa! Whoa! Whoa!

Hold yer Horses!

This is the Inverter Board!!!

Look at the FET just by those swollen Caps...

Change those 3 Caps AND that FET, let's go, already!

 |O
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Online wraper

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Re: Dumpsterdive TV repair
« Reply #11 on: December 21, 2016, 10:28:52 am »
Whoa! Whoa! Whoa!

Hold yer Horses!

This is the Inverter Board!!!

Look at the FET just by those swollen Caps...SAVE your money.

Change those 3 Caps AND that FET (test at least), let's go, already!

 |O
That is not a FET, just a dual Schottky diode, chances that it failed are very slim.
 

Online wraper

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Re: Dumpsterdive TV repair
« Reply #12 on: December 21, 2016, 10:39:40 am »
Yeah, I got that, already.

Why you guys telling him to change ALL Caps.???
 :-DD

It's from the dumpster!

He can go back and "invest" further after he's motivated - when it powers up!

I still see a FET...
First 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.
 

Online Gyro

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Re: Dumpsterdive TV repair
« Reply #13 on: December 21, 2016, 10:55:25 am »
Yeah, I got that, already.

Why you guys telling him to change ALL Caps.???
 :-DD

It's from the dumpster!

He can go back and "invest" further after he's motivated - when it powers up!

I still see a FET...

Why 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!


Quote
You would be surprised...
Huh?  :-//
« Last Edit: December 21, 2016, 10:56:57 am by Gyro »
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Offline KrisBendix

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Re: Dumpsterdive TV repair
« Reply #14 on: December 21, 2016, 02:24:06 pm »
Success!  :clap:
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.  :D
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.  :-//

 
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Online wraper

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Re: Dumpsterdive TV repair
« Reply #15 on: December 21, 2016, 03:04:31 pm »
Success!  :clap:
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.  :D
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.  :-//
Where are you located? If in Riga, you could get Samxon caps at Salvats, which are decent enough. Or Ormix http://ormix.lv/lv/catalog/category/id/G0240113 Elite 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.
 

Offline KhronX

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Re: Dumpsterdive TV repair
« Reply #16 on: December 21, 2016, 03:12:18 pm »
I could also recommend "egekecu" - http://stores.ebay.com/id=298040899?ssPageName=STRK:MEFSXS:MESST&_trksid=p2053788.m1543.l2653

First 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 that  :-+

I 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  ::)
« Last Edit: December 21, 2016, 03:15:57 pm by KhronX »
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Online wraper

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Re: Dumpsterdive TV repair
« Reply #17 on: December 21, 2016, 03:25:21 pm »
I could also recommend "egekecu" - http://stores.ebay.com/id=298040899?ssPageName=STRK:MEFSXS:MESST&_trksid=p2053788.m1543.l2653

First 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 that  :-+

I 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  ::)
About 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.
« Last Edit: December 21, 2016, 03:32:29 pm by wraper »
 

Offline KhronX

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Re: Dumpsterdive TV repair
« Reply #18 on: December 21, 2016, 03:45:42 pm »
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.
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Online mariush

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Re: Dumpsterdive TV repair
« Reply #19 on: December 21, 2016, 06:19:23 pm »
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.
 

Online Gyro

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Re: Dumpsterdive TV repair
« Reply #20 on: December 21, 2016, 07:19:42 pm »
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.
Chris

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Online Gyro

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Re: Dumpsterdive TV repair
« Reply #21 on: December 21, 2016, 07:43:57 pm »
You have better eyesight than I do! I can't make out the part numbers :D

I 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.
« Last Edit: December 21, 2016, 07:45:46 pm by Gyro »
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Online wraper

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Re: Dumpsterdive TV repair
« Reply #22 on: December 22, 2016, 03:32:39 am »
To "clear the air':
Guys & Girls, I have been repairing anything with a CRT since the 1980's.
It is true that when LED/LCD flat panels replaced most of the CRT's, I had long shut shop (in that area).
And 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.
 

Offline Monkeh

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Re: Dumpsterdive TV repair
« Reply #23 on: December 22, 2016, 04:22:29 am »
Okay,
I looked at the underside of the board, there is your DUAL FET INVERTER I.C. [smd--->8 legs].

I don't see its cap, though.

Tell me, this doesn't use any FET?

Since the bad caps are in the regular PS, he has no problem there...

Yes, 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).
 

Online Gyro

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Re: Dumpsterdive TV repair
« Reply #24 on: December 22, 2016, 01:20:20 pm »
Flame on, guys.
@aquamon:
I have already appologised if you felt that my reply made you feel bad. I genuinely can't identify which FET you were talking about, can you be more specific please.

Quote
You will find out, one day.
I'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?
Chris

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