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What is wrong with my tv? Please Help!!! Thanks in advance

post #1 of 19
Thread Starter 
First off I am sorry if this is not the right place to post this as I looked over the site and this seemed to be the only place.

I have a LG 42LC7D UK.AUSTLJM TV. I was watching it the other day and it just stopped working and this showed up. I fix computers and cellphones but know very little about tv's. Any information would be greatly appreciated.
post #2 of 19
YOU are in correct thread no prob.
Removed SEE UPDATE BELOW post # 5

Edited by tubetwister - 9/20/13 at 12:45am
post #3 of 19
Thread Starter 
Thank you Tubetwister for your prompt reply, I have been watching alot of youtube about this issue I will check out your links. I am thinking it is the t-con board but wanted to see if anyone could tell for sure before I wasted money on the board. Just hoping i don't have to replace the whole screen.
post #4 of 19
I'm thinking a board just don't know which one for sure hopefully the videos will help .or maybe someone will come along that knows for sure.
post #5 of 19
UPDATE post # 2 COMMON DIY LCD TV AND PANEL REPAIRS

Manufacturer or extended warranty will cover panel and circuits but not physical or water damage unless otherwise specified for the term of the warranty if your set is under warranty Refer to /use that warranty .

SCREEN CARE always consult your owners manual otherwise read below.

Moisture can permanently damage panel bonded tab connections. Bonded Panel Connection Tabs are inside at one or more edges of screen.
so you do not want any water or liquid to drip or flow behind screen edges nada. Light gentile dusting with dry microfiber cloth is best.
Never spray anything on the panel use dry microfiber or 100%cotton baby diaper or undershirt . USE only slightly moistened microfibre or soft cloth to clean screen . Windex can kill them in a heartbeat sometimes symptoms do not show up right away panel connector corrosion can take some time , also they can malfunction on their own without help . Distilled water or a few drops very mild dish soap diluted in water used to dampen cloth is best Or whatever your owners manual recommends .
Also anti glare coatings usually do not like too many liquids
Lots of well intentioned housekeepers and owners can ruin panels with windex . See below for DIY panel repair info

. Bonded Panel connectors deal mostly with CCFL/LCD and LED/LCD panels but can also apply to Plasma sets
Symptoms are usually vertical or horizontal lines and or ,vacancies they *may affect only part of the screen
See further below for DIY panel repair info


Other common internal LCD/LED TV REPAIRS

TV Sets and PC monitors that shut off or will not turn on are usually having power supply failures some are easy to repair .see below
Common procedure is to replace faulty boards . *Some power supplies can be repaired by simply soldering in a few new capacitors* to replace failed parts . sometimes a visual inspection can spot bulging capacitor tops they must be replaced with like parts and correct polarity observed
plenty of You Tube videos about DIY "replace capacitors in LCD TV "
also other board parts can fail . Other boards are usually replaced due to embedded non serviceable parts /circuits .

Watch these YouTube videos especially the playlist from Grants Pass TV repair you might find your problem

LCD Display Symptoms and causes.
http://www.youtube.com/watch?v=DedJvyNm_s4

Then if needed watch playlist
http://www.youtube.com/playlist?list=PL7556A758748586E9


If You find a bad board get the number off of the board itself then Google that # something should come up also Ebay has lots of boards
or you can also search the part# at shopjimmy.com link =
http://www.shopjimmy.com/

Sets within a given model number* may use different boards so best to use actual board number when ordering replacements

.You can first gently wiggle board connectors maybe check panel connectors

Know that bonded tab panel connectors are fragile *some times* they can be fixed if not then panel must be replaced we have threads here regarding fixing bonded panel connectors sometimes it actually works ! (see below)

You can apply light pressure or do inspection of bonded tab panel connectors if those are suspected might not be a bad idea (see below)
Only thing is they *usually* all don't go bad at once they usually just affect picture in one or more sections some times vertical or horizontal lines
or vacancies depending if they are on top ,bottom, or side of panel that varies by TV model.

TV is basically an PC monitor with TV resolution and Tuner + HDMI connectors
and audio
symptom displayed on *All inputs yes /no ?


**************** Cautions *************************

LCD CCFL backlight TV Can have ~700 -1000 + AC working voltage to operate CCFL (florescent tube backlight) take appropriate cautions

Plasma TV also has similarly high working voltages

LCD/LED does not have high voltages other than (like the others) mains voltage at Power supply board as do sets other than battery potables .



***************Here is info on Bonded Panel Tab Connection DIY Repair ************ *Mostly LCD/LED *Some Plasma sets .
Panel connector fault Symptoms are usually vertical or horizontal lines and or ,vacancies they *may affect only part of the screen

*Some times* you can Fix the panel bonded tab connectors by putting a little foam tape or something maybe small rubber tubing under the pad retainer clip Know this is not a permanent repair but in some cases it can last for years.
Cheaper than a new set *most* sets are* usually not worth putting new panels in .
These repairs may or may not work.
There are more permanent repair methods requires more skill and special materials/parts you can google "LCD Panel Tab Repair " or same or similar search on You Tube or start here for more information on that. http://www.avsforum.com/t/1336237/universal-tab-repair

easier temp panel repairs
Here is a video http://www.youtube.com/watch?v=vCExlSnG4yY

Here is thread here at with detailed pictures of the the fix here at AVS scroll down to post 29
http://www.avsforum.com/t/1173106/kdl-xbr4-half-the-screen-dark-with-slow-pixel-refresh-all-inputs

Here is another thread same subject
http://www.avsforum.com/t/1311478/double-image-and-3-horizontal-lines-on-ln-t4069f-lcd

Don't forget a thumbs up if this has been helpful for you!
Edited by tubetwister - Yesterday at 12:33 am
Edited by tubetwister - Today at 11:55 pmost # 2 REVISED a little more information

Edited by tubetwister - 9/20/13 at 12:43am
post #6 of 19
post #7 of 19
Thread Starter 
So I went ahead and replaced the T-Comm board, and ..... No change at all looks exactly the same. So now I'm lost on what to do, I have this $30 t-comm board I can't return I didn't use and I'm not sure what to do with this tv. I hear a buzzing coming from the power board not sure if thats normal. I took all the boards off and looked for broken solders or "bulged capacitors" I know capacitors can go without bulging and look normal but I don't have the equipment for testing. So I am thinking the next step is throwing the tv out. Any suggestions anyone??
post #8 of 19
Thread Starter 
This is what I am looking at:






post #9 of 19
check out this tread maybe ? http://www.avsforum.com/t/1373343/problems-with-a-sony-kdl-46z4100-3-wide-vertical-bars-of-discoloration
or this one http://www.lcdparts.net/howto/symptom.aspx

could be bonded tab panel connectors ?
looks like you *may have * have AU Optronics panel not the best thing out there not worst either , Samsung ,LG ,Sharp,Toshiba panel would be better .although your panel connectors are vertically oriented so that makes sense of what is pictured .


OTOH you might want to google " wide black and white stripes on LCD TV " or You Tube search or even (I hate to say it but Bing ) *sometimes* comes up with different results than Google OTOH * usually * Google is better. if you put light pressure on the bonded panel tab connectors at panel or the board and it starts working better that *may be the answer ! You may have to remove front plastic bezel (usually do ) to inspect bonded panel tab connections the panel has it's own frame behind front plastic bezel. good luck!


TABs, or tape-automated bondings, are an integral part of any LCD monitor. These bondings connect the information they receive from the processor (T con board or other display control board ) and send it to the tiny transistors in the panel that create the electrical currents that ultimately affect which colors or if anything you see on screen. A TAB fault -- also called a TAB failure -- happens when these bondings are damaged or otherwise disconnected from the processor. When this happens, entire rows or columns of pixels go dark because they aren't receiving any messages from the processor to create their colors. TABs can usually be reattached by a professional TV repair person but over time may become so loose and so repetitively problematic that they may need to be replaced entirely.

*usually* tab failure will affect part of screen if only one connector faults but not always .

IS your replacement T Con board used and known to be good or just a salvage pull (safe to assume if it is not new ofc. ) ? does it have a warranty,? it *could * be faulty* still ,vendor willing to exchange for another ? If it is good he has nothing to loose , otoh if not and he corrects problem he has a satisfied customer .
If the board turns out good (maybe second one does not work) maybe offer to pay shipping if not vendor should pay, even brand new boards can fail.
Read more: http://www.ehow.com/info_12171138_causes-vertical-lines-lcd.html#ixzz2fUKj2ve2
good luck
Edited by tubetwister - 9/20/13 at 7:27pm
post #10 of 19
removed
Edited by tubetwister - 9/20/13 at 7:26pm
post #11 of 19
forgot about buzzing at power panel ordinarily I would say it is not supposed to Buzz are screws tight? there is however always the potential they can buzz lightly
because like the LCD back light inverter board they have transformers (The metal /copper coil things ).

OR you could have a capacitor drifting out of range and causing DC ripple or a faulty voltage regulator almost anywhere.
you would see that with an digital AC volt meter ( DVM .) likely on the 12V rails o rails for inverter , main board ,and or T con boards as an AC voltage component with DVM on AC scale.

You should not see more than .25 ACV if any or so on* other than CCFL back light and mains in*. You may also have NO 12vdc present at Tcon board that would explain white picture and point to power supply an inexpensive DVM maybe 10-15.00 Radio shack and amazon have them or maybe you have one and you can measure power supply rails.

Voltages are printed on power supply board at connector ( I think it's safe to assume backlight inverter board is getting voltage display lights up otherwise you wold have darness only.
your symptoms are looking like maybe T con board 12 Volt working voltage is absent (Power supply fault ) bad T con board or panel or connector I would investigate
voltage at T con board at this point and power supply outputs. that is the more likely outcome.no color can point to this.
post #12 of 19
Thread Starter 
Thanks for the info, I have googled everything I can think of and watch enough youtube videos on lcd tvs to make me sick lol. I guess I can end my Boycott of MSN and Bing and try to search there.

I have volt meters and such but honestly am not to familiar with tv's to even know where to check volts let alone to start soldering things. I would rather buy the board if I knew which one.
The buzzing Im hearing is definitely not normal I don't think, sounds like something is fried on power board maybe. I left it on for a little while, while I was cleaning up and noticed on the screen the Bar all the way to the left has Colored lines running down it.

I checked the tabs over and over again, there was one video on youtube where this guy had the same problem but only half of his screen was doing this. But the bars looked exactly the same. He tapped on his and it went away and came back, I have tapped on all of them and it doesn't change at all.

Again I appreciate your help, I gotta get this tv fixed somehow, It broke at the worst possible timing. ;(
I'll search again, and if I end up figuring something out I'll post an update to inform people of the fix.
post #13 of 19
needhelpny

You have a DVM you have a leg up there in this You tube playlist the poster ( he owns Grants Pass TV Repair btw so not a newbie) goes through basic power supply voltage checks in detail probably one the first few videos in the playlist it's not that hard the voltages are printed right on the boards you are only concerned with only a few working voltages
coming out of the power supply think of it this way power supply 12V to Tcon board present then you have a bad t con board or panel or tab connector . since both sides of screen are affected I'm thinking a board or board level component.
not present maybe power supply . I think it is a lack of voltage to Tcon board maybe power supply fault or where ever it gets 12v usually if another board is faulty the set will not turn on or display anything or it can shut off ! checking the voltages on power board is the only next logical step it's not hard just remember black wire or metal chassis is meter ground. Check out the playlist check the volts .

Looks like the mainboard supplies voltage to the tcon board ofc it has to come from the power supply so it is probably only a pass through
maybe circuit trace + main connector pin ,crappy design but thrifty ,( no offense ) hopefully not wired parallel with main board B+ always better to have each board with their own 12V pin at the power supply so I'm, hoping this is an independent 12V pass though just saying in any event no matter how they made it that's why power board outputs are key looks like they didn't use different colored wires but maybe colored stripes . in any event you can ground meter (black lead to metal chassis. (you sure this thing wasn't made in North Korea ?) biggrin.gif
Hopefully they printed voltages on power supply board could ne there is a 12V pin designated on T con board also as that is a AU Optronics panel they at least are pretty conventional usually unless that is a custom board for LG but more likely knowing LG it's a generic Panel.


again just take it slow check the volts .
Edited by tubetwister - 9/20/13 at 9:57pm
post #14 of 19
Thread Starter 
I started testing some of the connections going to the t-con board. they all tested good except one. The is the cord that has 10 connections ( 1,2=19v / 3,4=GND/ 5=6v / 6=GND / 7 = 3.4v / 8 = GND / 9=12v / 10=GND ) I was able to get the correct reading off all but #5 , I didn't get any reading at all which is supposed to be 6v. Not sure if this would be causing it or not. All the capacitors look good. I am unable to test in circuit at the moment. But will continue to investigate. I have had a gut feeling it was the power supply, I think if I replace the board it was solve the issue. I just really wanna make sure first ya know.
post #15 of 19
a missing 5- 6 volt rail can sure kill the control circuits on the board they typically use ~5v logic asic chips maybe ~ 3v pin 9 would be your 12v rail makes sense at least at the PSU if that is working without that nothing will happen ofc the tcon needs 12v also but the loss of any voltage anywhere is ofc a fault .

I wonder if 5VDC can be found elsewhere temporarily( not likely if that is the only 5v rail on the PSU) or if you have a 5vdc wall wart ?, USB is
5V and 500mA.also plenty and then some also if you have something phone USB charger? OLD USB cord? you could get current from ofc observing correct polarity maybe 5vdc from PC psu ? or 4.- 1.5 v batteries maybe do some surgery on an old remote or try to connect to the batteries somehow or connect it up somehow paper clip? or a 9v battery that only has 6 v left? and power up that circuit.

RU testing at PSU connector if so missing 5vdc is probably a good find . switching power supplies in most TV's aren't well made and often fail on at lest one or more rails 12v rail failure is more common but not always TV PSU fails more than PC PSU. the older the TV the more prone it is to fail any kind of TV ,electrolytic s fail as they dry out or drift out of tolerance . newer 2008 +solid caps are better . if you were lucky enough to get them that soon some sets did not solid caps are better .sound like you are making good progress. biggrin.gif
probably the majority of LCD or LCD/LED TV's at recyclers have PSU failure .
Edited by tubetwister - 9/21/13 at 3:08am
post #16 of 19
Thread Starter 
Please explain a little further on how I could test this with a usb cord wire? The cord is uplugged in picture, but it goes to the main board under neath t-con board. It states 6v next to it, its the only one I could not get to register on meter. Thanks again for all your help.

This is it:

post #17 of 19
Actually I meant to use an External USB power from another device to pin 5 on PSU and ground to get your 5-6 volts .some options below

The usb connector in the set *may not have power if your 5V PSU rail is not working .but you could verify with meter.if you have 5 volts there tap that 5vdc temporarily. actually that might even work longer because it is a 500mA spec and should run the board although a functioning PSU is preferable for the long term.red wire is +5vdc black is ground
you will probably need an old usb cord for thisĀ 

To make a temporary connection to pin 5 you van try a paper clip or pin from the wire side of connector when it is plugged in or maybe stick a straight pin through the wire to pin 5 and attach 5 -6 volts to that or maybe you will have to a strip a little insulation from the wire same for ground unless you can find a ground on t con board simple:D

Problem is if T con board does not have a 5-6 volt from power supply your usb *may * not have voltage present either that would be a good thing to measure ,
if you have voltage at usb again you can tap it temporarily.to pin 9 and ground for testing pourposes. see pinout below

OTOH *IF you can measure 5vdc at a circuit board jumper you might be able to temporarily make a connection from there to pin 5 on the PSU connector not for too long though only to verify if it makes your set work.
that should work temporarily for verification purposes or maybe you can bridge a 5-6vdc connection from another connector on another board if you can verify one with 5-6 volts present .temporarily I would not probably reccomend to operate the set long term like that because sometimes tapping another rail can over stress it but unused usb might work if it has voltage (if they made the power to usb to specified minimum usb standards )


For external usb power plug usb cord into another device or usb phone charger you could even try the USB port on on the TV in the off chance it has 5Vdc from another rail you (you can measure that and see )you may have to cut a usb cable and get to the wires
here is USB pinout 2 wires are 5vdc +/- the other two are data +/- anyway that would get you 5vdc you are missing one wire to pin 5 another to ground simple:D

USB pinout
Pin Name Cable color Description
1 VCC Red +5 VDC
2 D- White Data -
3 D+ Green Data +
4 GND Black Ground


Don't forget a thumbs up if this has been helpful for you!
Edited by tubetwister - 9/22/13 at 3:39am
post #18 of 19
Thread Starter 
GOT IT WORKING !!!! HAHA, I was fixing an ipad screen using my heatgun when I remember hearing on one of the videos that someone uses a hair dryer on tvs to get the capacitor working for a little while or something so I walked over, turned the tv on and as soon has the hot air hit the power board the picture came back in literally seconds. I have turned it off and on and waited, its been 20 mins and still working. The only problem I still got is that when there is no video playing just black screen you can still see them bars really faint if you look hard. Cant see them when video is playing at all, so not a big problem. The other problem I have is I don't know which component failed that is working now. So I'm thinking of buying a power board as I'm sure it will go again soon, Right?

And I looked but don't see where I can give you a thumbs up, you were defiantly very helpful. Out of all the forums I posted in for this issue you were the only one that continued to help me and give me hope to proceed on this repair. If it weren't for you I would have gave up already. Thank you very much.
post #19 of 19
ha ha glad you got it working ! could be a capacitor or thermal regulator maybe more likely a capacitor that is most common thing they have cold spray at radio shack or electronic repair supply store or website you can spray individual individual
parts and pinpoint /isolate that way and if you are comfortable soldering new parts to the board you can do that I wonder if the folks you bought the t con board would exchange
Tcon board and credit your $30.00 toward a PSU board ofc they would probably expect you to pay shipping .
OTOH if you find the fault on your PSU board it might be cheaper to fix the board sometimes I fix them for$3 or $4 US in parts
In any even ether way you decide ton fix it it beats paying $5- $600.00 usd for a new set to replace one that was otherwise working OK ..

CHECK THIS OUT Repair Kit, LG 42LC7D-UK, LCD TV, Capacitors, Not the Entire Board $15.95 us kit includes 9 capacitors some solder a desolder wick and link to on line instructions . about twice what you would pay just buying capacitors but convenient. LCD alternatives has web site you can find generic instructions on for free just another option if the prob is a capacitor or two (likely )
I bet if I had a dollar or euro or GBP for every CCFL/LCD and LED/LCD set that gets tossed out in one year for just a bad cap or two I would have millions !
repair shops here charge ~ $ 250.00 to fix that ofc they have their diag time + hourly rate and fixed overhead it's just what it is.
and when you can buy a decent tv for $250.00 - $600.00 now it's hard to justify a $250.00 repair on an older set so kinda tough for repair shops .
even a modern $3-$400.00 set can out perform an older set that costs 10 times as much .
one thing I'm glad of I went from CRT to flat panel and skipped DLP or RPTV altogether those thing had way to many issues !
I worked on a couple of those and decided they were not for me now you can't give them away.
I don't do it for a living but I fix stuff for friends now and then.

Oh I will need your postcode so I can invoice you for consultation services biggrin.gif just kidding !


It will probably go out again something is failing if you decide to replace any capacitors make sure to get same uf value voltage can be higher for example you can use a 30v where a 20v goes but voltage can never be lower t they must be low esr 105 degree spec
or they will not last . Panasonic and Nichicon are good brands amazon has them so do Digikey and Mouser on line Radio shack usually does not have 105 degree spec .
capacitors are polarised like a battery the stripe side is always negative and must be removed and replaced the same way it came out or it will fail.
caps typically run about .80 ea US from mouser and Digikey or maybe 1.50 on amazon but if you are in UK you probably have plenty of sources there. .
shipping is a lot cheaper at amazon though .

thumbs up are first the little green thing on the right bottom in the blue box here just left of the multi button

cool maybe the board is cheap also I'll take a look at shopjimmy.com


Looks Like about $80.00 us for a PSU board ofc if you do order one use the part # on the board itself the parts can vary within a given set model
might be cheaper maybe $5.00 -$10.00 + cold spray to fix your board if the filter caps are bad I usually replace the 3-or 4 next to the bad one also

Shopjimmy.com is out of stock of th 3 possible part #s but maybe someone in UK or on ebay has one I'm assu[/SIZE]ming that is your location by the set model #

EDIT
I thought I would post this so we can just point to it
I made a new thread about power supply diag and repair
if you get time and want to check it out maybe let me know what you think?
http://www.avsforum.com/t/1491814/common-diy-diagnosis-and-repair-info-for-plasma-led-lcd-and-ccfl-lcd-tv-sets-monitors-and-display-devices-mostly-power-supply-repairs
Looks like you are on third base no outs
so you will be on home plate soon.
Edited by tubetwister - 9/23/13 at 3:40am
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