Panasonoc TX-L50BL6E Horizontal lines on left side of screen

[dicky96]

Hi guys
I have this Panasonic TX-L50BL6E here

The original problem was blown backlight LEDs and a short circuit power FET on the backlight driver PCB

I've replaced the whole set of LED strips and the short circuit power FET. The set now powers up but is has another problem

When first powered up I get an image with the wrong aspect ration (too narrow and too high to fit the screen). Also on the left hand side of the screen there are regular spaced black horizontal lines that fade away towards the centre of the screen. The right side of the screen looks fine. These can be intermittend, the black lines flickering in and out.

I can see the same horizontal lines on the onscreen menu and HDMI 1 message block before the image from the video source appears.

Then after 5-10 seconds or so the picture disappears and I have a mainly purple screen with vertical lines, but no horizontal lines. This stays on screen until I power off and back on again, in which case the same sequence occurs

What is likely to be causing this problem?

best regards
Rich

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

No one?

I tried the TV with no video source and menu on screen. It behaves differently with no video source, I don't get that purple stripy screen after several seconds.

The right hand side is OK, the left hand side has the horizontal lines which flash on and off at a regular pace and the brightness changes when the lines are on screen

Here is the video link
https://youtu.be/v6XzUUNA9kM

I've not seen anything like this before, How can I diagnose this fault???

best regards

[Biruslapio]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

The aspect ration i blame the motherboard,but it looks like your screen is defective also,at the first picture with the menus the bottom is trembling,common display fault,what a shit tv to have this many problems all at once.
Update firmware on main,and/or enter service menu,try to do a factory reset.
http://av.jpn.support.panasonic.com/...uk_cis_02.html
latest firmware link,i hope that this TV can output comprehensible display long enough for that to be possible.

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

OK a bit of history on this TV. It failed while still under warranty and the owner could not find the receipt so they dumped it in the garden. There it stayed for a few months until a friend of mine told me it was there and said I could have it for free if I went to fetch it. Fortunately it was very near to me and it had been put outside over the summer. It hadn't rained here since March until August when we had one heavy shower so it only got wet once. It had thoroughly dried out in the sun by the time I got my hands on it in September.

I thought seeing as it is only a year or so old and it's a nice 50 inch smart TV for nothing it would be worth repairing. So far it cost me under 30 euros to replace the back light strips from Aliexpress and the power FET from ebay.

So that's the history behind it.

Now I saw that ghosting effect you mention on the first photo but I think it is camera shake or something. I didn't notice it on screen

OK so from your suggestion I got into the menu (I don't have the remote for this TV by the way) and this video shows there is a good picture all the way to the bottom of the screen.

This video also shows the weird flashing with horizontal lines, ticking away like a metronome until all of a sudden........... whammmm wtf?

https://youtu.be/0VF-RTghi8o

Restart the TV repeats the process

Ideas?

best regards
Rich

[budwich]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

well, just because the tv "dried out" doesn't necessarily mean that everything is back to "normal". Water carries with it many things along the way such as dirt, chemicals (in the air for rain), smoke particles, etc which when the water dries, state behind as "contaminates" for electrical circuits. These can cause shorts or "stray capacitance" which are not good. Further, the water may ingress into the panel layers and may not actually dry out.

you should try to use an input of a known test pattern (color bars that fill the screen), then you will likely get a better idea of what is and what isn't happening. Having said that, some of the symptoms (black lines on one side), potentially indicate bad drivers / connections to those drivers in trouble. The "aspect issue" sounds more like a main board issue although it could be contamination on the lvds cable going from the main board to the tcon... try cleaning and reseating.
Vertical lines are usually not good unless they are uniform across the whole screen which then are likely a board issue.

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

So you did do a firmware update?

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

Could strip it down a little, see if theres any corrosion, rust or corruption under there. I see you have already been inside to do the led replace, did you take a good close look at the scan driver boards?

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

.

[Biruslapio]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

In this new video of yours seems like the aspect ratio problem is gone?
I say LVDS could be problematic and this flickering is main or t-con,the backlight does not become brighter etc.
This model has T-CON at the bottom of the tv,so if it got wet water sure ran down to the LCD board,open it up and look for oxidation,stop turning the tv on because if water is in it,electricity running through speed up the process a lot.

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

OK guys thanks

I had a look for corrosion or deposits on the main board and it looks really clean to me. I removed it and checked both sides. The only corrosion is on the HDMI and component/composite connectors and metal casing of the Tuner.

I haven't checked the TCON board for corrosion/deposits but I will have a look. I did try reseat the LVDS already at the main board end but not the TCON end

The Panel PCBs are dry and clean, I already removed the panel to replace the backlights as mentioned. And fixed the backlight driver PCB fault

I do agree - the aspect ratio looks OK with the menu on screen but not with a video source

Believe me it is very dry in there. This would have got wet in the heavy downpour we had in August (only once every three years or so do we get ANY rain at ALL between March and November so I remember that downpour well. Locals came out and danced in the rain!) We only see 3.5 inches a rain a year here. Its been in my workshop since September, which due to the air con is a very dry environment. So it's absolutely dried out for sure.

Also in the summer here the ambient temperature outdoors never goes below 20C (68F) even at night. Heavens it only gets down to 15C (59F) absolute minimum at night on the coldest days in the middle of winter!

I'll check for more corrosion/deposits and post the pics

Rich

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

So you did do a firmware update?

Sorry not tried that yet, not sure I can keep the picture on screen long enough to do it TBH

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

Well I'm jealous now, that's a dam fine climate, it's 26 F and windy as hell right now in the midwest of the U.S. puts the windchill at about 0 F.

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

Wonder if that strobing could be a faulty voltage regulator on the mainboard?

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

Thanks, yeah the climate is why I moved here from north west UK where it was dreadful

Wonder if that strobing could be a faulty voltage regulator on the mainboard?

Sounds possibly but seems very regular like tick tock. I think maybe a processor is doing that. I would have to check if I always get the same number of strobes before the purple screen

[dicky96]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

OK I can get a working main board for this TV for about £30 or so. Seeing as I paid nothing for it then it would be worth the repair cost, including the £25 I spent replacing the back lights, I would still be well in pocket if I then sell the TV.

Is there any way I can prove with reasonable certainty this is a main board fault before ordering?

best regards
Rich

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

I think the mainboard is worth a shot, price isnt too bad, could always resell it or its nice to have a backup board.

[nomoresonys]

Re: Panasonoc TX-L50BL6E Horizontal lines on left side of screen

Thinking if theres nothing wrong with the scan boards, should be main or tcon issue.