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Author Topic: PROJECT: HOW TO FIX AN LCD TV FOR LESS THAN $5  (Read 9112 times)
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cOOter
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« on: October 01, 2012, 04:01:52 PM »

<a href="http://www.youtube.com/watch?v=8l0AUj8QUkg" target="_blank" class="aeva_link bbc_link new_win">Samsung TV - Power on Problem - Capacitor Replacement</a>

The above video shows how to fix a Samsung TV that won't power on.

WARNING: HIGH VOLTAGES INSIDE THE TV THAT CAN KILL

Yesterday I was given the same brand TV for free - it had the same issues as the one in the video.
http://www.samsung.com/au/consumer/tv-audio-video/television/archive/LA40A450C1HXXY


Here's my LA40A450 with the back off.



Hello 2x blown capacitors on the power board.



Outdoor electrics is great - but watch out for the bird shit.
Quick trip to J-Car to buy 2x 25v 1000uF capacitors.
Here I'm removing the old ones and installing the new ones.



2x new capacitors installed in less than 5 minutes - a little bit bigger but are jiggy.



Free 40" LCD TV  ($1200 when new four years ago) fixed for $2.60
The lady I got it off was quoted $200 for the same repair.

 toothy4
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Thunderbird
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« Reply #1 on: October 01, 2012, 04:27:18 PM »

Well done! I hope Jaycar gave you low ESR cappies to replace those blown up ones. If the repair doesnt last very long that will be the issue, the cappies will get too hot and boil all their innards out.

Enjoy your new "programming"  Tears
 cya
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"If a clutered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign."  Albert Einstein

Well, I have the cluttered desk, I guess that's a start!
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Reply #1 on: October 01, 2012, 04:27:18 PM

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« Reply #2 on: October 01, 2012, 04:40:48 PM »

Rodger that. I should have gone to 35v I think. Ow well.



$1.30 each almost broke the bank.



 happy8
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« Reply #3 on: October 24, 2012, 10:29:53 AM »

<a href="http://www.youtube.com/watch?v=z0jiIyb-ivg" target="_blank" class="aeva_link bbc_link new_win">LCD TV FAULT FINDING &amp; REPAIR</a>


Brand: Hicon (aka Conia)
Model: HLCD2238DHD
Specs: 22" 16:9 1920x1018p LCD screen.
TV rated at 60 watts and runs off 12V 5A
Inbuilt DVD, DVT, HDMI etc.

I was given this TV for free because the screen was playing up. This was my first attempt at fixing a TV. Confidence to even attempt such a repair came from users on YouTube and their helpful videos I've been watching over the years.

Fault Symptoms: Unit would always power on ok, but colors were blurry with fuzzed out edges in some settings like DVD. Other settings like TV a black line would appear down the center of the screen, Before pulling it apart it had all the signs that it was stuffed. Turned out to be an easy 2 minute fix that cost nothing. It's now working perfect and serving as my first ever HDMI computer monitor and DTV unit.


Top middle - Still working fine with cool picture.
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Reply #3 on: October 24, 2012, 10:29:53 AM

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Thunderbird
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« Reply #4 on: October 24, 2012, 12:08:15 PM »

Looks good, stops yet more crap going to landfill.

Dont tell too many of those CB dickheads though otherwise we will have none for ourselves  Tears not that CB dickheads even own soldering irons let alone know which end to use  Smoking
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"If a clutered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign."  Albert Einstein

Well, I have the cluttered desk, I guess that's a start!
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« Reply #5 on: October 24, 2012, 12:32:32 PM »

Good thing about the Hicon - all it needed was a whack on the top, and all good.

[add Fonzy icon here]
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Reply #5 on: October 24, 2012, 12:32:32 PM

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« Reply #6 on: October 24, 2012, 01:41:59 PM »

Ahh 'percussive maintenace' I use it when my 'self repair' shelf isnt workin. No joke, I had one in my last computer business, some 'not economical to repair' cases were left on the shelf after customers rejected the quote to repair and instaed replaced their computers or other electronic doodad. Every now and again, I'd have a clean up of the workshop and try out anything I thought might be worth salvaging for bits or whatever, half the damn things would work and show no sign of a fault for ages! Even non computer items I repaired would do it! Sadly, the shelf wouldnt fit in my car when I moved by repairs to home base, so now my crap just gets worse on the shelf not better!  Tears
I even still have some of the items here at home, and damn it they still work. Ahh the myseries of the universe!
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"If a clutered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign."  Albert Einstein

Well, I have the cluttered desk, I guess that's a start!
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« Reply #7 on: October 24, 2012, 01:46:14 PM »

Good thing about the Hicon - all it needed was a whack on the top, and all good.

[add Fonzy icon here]

LOL   Wooooooooooooooooot!      Boobs
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« Reply #8 on: October 24, 2012, 03:34:20 PM »

Ahh the myseries of the universe!

Arrrhh, yes, like what came first, the Hicom or the Samsumg.  read2

Samsung guts are in a Hicom so some say.

director I've had my arvo nanna nap DaVo, and soldiering iron is on.  glasses11
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« Reply #9 on: November 05, 2012, 08:01:30 PM »

UPDATE: Bugger, the Samsung is on the blink again.

This time I think the backlight inverter is rooted, or the 24v from the power supply has stopped for some reason.

TV powers on OK, and has sound but a blank screen.

In a dark room with a light above the screen I can just make out images, so I guess the LCD drive board is OK.

I followed the steps in the below video to check the backlight inverter board, but I'm not getting any power to it.

<a href="http://www.youtube.com/watch?v=oE6K4xBVweA" target="_blank" class="aeva_link bbc_link new_win">Troubleshooting LCD Backlight Failure Samsung LNT-4066</a>




The bottom cable from the power board isn't sending any juice to the backlight inverter during or after start up.

The top cable is listed as 12v, but is doing about 11.5v

Any ideas all you smart nerds out there?  book1
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« Reply #10 on: November 05, 2012, 08:28:30 PM »

11.5 volts on the 12 volt rail is probably ok. Is there anything else hanging off the 24 volt rail on the PSU end? Did you check the 24 volt output at the power supply? If the power supply isnt putting out 24 volts, I'd be looking for a fuse, it might not look 'fuse' like, but will probably be marked F1 or F2 etc on the board. Next up, check the diode on the 24 volt rail on the psu see if its shorted or open. Cant think of anything else atm, but if ya dont get it going in the next coupla days, Ill bring over some special goodies to test it with.
I have some spare inverters as well.  cya
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"If a clutered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign."  Albert Einstein

Well, I have the cluttered desk, I guess that's a start!
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« Reply #11 on: November 05, 2012, 08:38:28 PM »

11.5 volts on the 12 volt rail is probably ok. Is there anything else hanging off the 24 volt rail on the PSU end? Did you check the 24 volt output at the power supply? If the power supply isnt putting out 24 volts, I'd be looking for a fuse, it might not look 'fuse' like, but will probably be marked F1 or F2 etc on the board. Next up, check the diode on the 24 volt rail on the psu see if its shorted or open. Cant think of anything else atm, but if ya dont get it going in the next coupla days, Ill bring over some special goodies to test it with.
I have some spare inverters as well.  cya

Special goodies are good  icon_cheers

The fuse at the 240v in is good.

The second fuse in the center of the board is good. TV wont start without it.

All cables have been unplugged and replugged to make sure connections are jiggy.

I'm out of the shed now (bloody mozzies) otherwise I'd pull the power board back off and have another look at the solder joints on the boards under side.

<a href="http://www.youtube.com/watch?v=XdsDxKkcesg" target="_blank" class="aeva_link bbc_link new_win">Samsung LCD backlight fix.</a>


I had it off today and noticed similar shaped solder joints like the one shown in the above video. (I hadn't seen this video then)

I'll do an update tomorrow. Cheers  thumbsup
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« Reply #12 on: November 06, 2012, 02:07:44 PM »

Update: Nah, soldering the joints didnt work either.

Still no power from the PCB to the bottom of the backlight inverter.

If I knew for sure it's the faut of the inverter, I'd just replace it, but if it's the PCB, then it's pointless buying an inverter.

I'll have to see if Chopper can fit me in for a service.  icon_sunny

 Bike
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« Reply #13 on: November 19, 2012, 04:12:22 PM »

UPDATE: The thing has been sitting in the shed pulled apart all week.

I was about to order a new back light inverter for $55 delivered from the US, but I thought, have one more looksie cOOter.  toothy3

It helps to make sure all 16x back light CCLF tubes are in their socket holders.

If only one is disconnected, none will fire up.

Tube #5 wasn't in it's holder, thus the high reading on #5 the other day.

Yeap, so I pulled transformers off the back light inventor board for no reason.

OK, it's working now  - I guess my re-soldering passed.

Chopper was a great help as well going over everything with his yoyo. No broken strings  thumbsup

It still might be a bit dicky on cold starts with a slight blink.

Brother Darren was using a power drill in the shed behind me today, and the 200 watt TV would go blank as if the PCB wasn't getting enough power. (we share the same 240v 10amp extension lead from the house 20 meters away)

Not sure about that yet.

Now it's back down stairs on the test bed. (oldies living room TV stand)

Smoking
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« Reply #14 on: November 19, 2012, 07:00:13 PM »

Good to hear that its working once again. I have no luck finding a service manual or circuit.  Only other thing I can think of is to try each tube out with a CCFL tester, an old laptop inverter might do the trick, and I have seen someone use the base of one of those compact flouros as a tester, pretty dangerous though, just how we like it  icon_jokercolor
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"If a clutered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign."  Albert Einstein

Well, I have the cluttered desk, I guess that's a start!
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