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Equipment Repairs => LCD TV forum => Topic started by: donnie1 on October 24, 2010,09:14:28

Title: LG 26LC46 multi coloured vertical lines
Post by: donnie1 on October 24, 2010,09:14:28

hi i have a lg26lc46 lcd tv which has developed a fault, when powered on with no input connected, i.e aerial, i get a grey screen with backlight on [see pic 1], once i connect the aerial i get vertical multi coloured lines all over the screen[see pic 2], with screen glowing [the glow moving from left, right, centre]

i have checked the tcon board fuse and 12v b+ supply, which i found to be there, i have replaced the board twice, and still no joy, i am wandering could it be from the main board

i have also checked the main board voltages, all seem ok except a 3.4 on which is slight low at 2.4v

any suggestion would be welcome the main board is EAX35231404, the emi filters were tdk, i have downloaded the factory manual ceratech filter solution, and from the information provided, i have discovered that the emi filters and resistors mentioned in the manual have already been deleted and shorted as advised

any suggestions would be welcome

thanx

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: sparky on October 24, 2010,10:16:48

hi
if you have changed t-con panel prob
 try connecting to another
tv from scart to scart if pic ok
then prob screen
dave

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: Turnip on October 24, 2010,13:22:20

Hi,

aWith a 26'' and that problem. T-con and Scart OP checked, there's a thought to twist the screen to see if things change.

Lost a few me'self to screen probs, usually Philips  - Chris.

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: donnie1 on October 24, 2010,15:45:00

hi
dave tried using the scart as an input with  a freeview  box, the multi coloured vertical lines still appear, if i am correct the purpose the the tcon board is to convert the LVDS signal to a TFT drive signal, which is then passed  to shift registers [memory chips] on the lcd panel and addressed to the pixels via the drive ic

ps.. with no data input i.e scart or aerial connection, or even removing the lvds cable from the tcon board, the screen is greyish / white with no lines

the fact that there is colour lines, but no video signal [picture], i would say means that there is continuty between the main board and lcd panel [ 24bit RGB signal], but for some reason the signal is shorted to ground or lost, and therefore is not processed, hence no data output to the panel.

I think maybe the replacement  tcon's could of been faulty or the mainboard is not transmitting  24 bit RGB signals

Any thoughts would be welcome

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: sparky on October 24, 2010,18:29:37

you have the tv thats faulty on showing the fault,
you then connect scart out from av1 to anther tv
thro scart not freeview box

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: Turnip on October 25, 2010,13:23:19

Hi Sparky - well said - like the first time - Chris.

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: donnie1 on October 26, 2010,09:19:48

hi

sparky tried connecting the tv to another tv, via scart, i got no picture just grey screen on the faulty unit, without the multi coloured lines, or audio [the other tv worked fine]i tried did swapping the aerial between the faulty tv and the working one, so one was the master and the other the slave, with the scart connected. still no joy

One thing i have noticed now, is that when i turn on the tv, the multicolored lines do not appear any more just grey screen with audio

regards

Title: Re: LG 26LC46 multi coloured vertical lines
Post by: daz on October 26, 2010,10:08:10

hi
had a similar problem on another lg,turned out to be a 3v3 reg on the signal pcb, voltage was correct but a lot of ripple, suggest you scope the outputs of all the regs.
good luck
daz