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Tech Chat Repairing "Colour" Televisions

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Hurty
(@hurty)
Posts: 99
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Topic starter
 

Thought I would bring the Television Repair subject up to date a bit. Terry and myself have been working through all the televisions used in the Sky News Office. There are about 40 in all and are 49" LG LCD televisions on the whole with two 60" LG LCD units. These where installed in 2017 and have been running 24/7 since. The pictures have all gone blue or somewhat blue with little or no red or green. They look just like dead red or green guns on a CRT. The problem is the LED backlight yellow filters that have cracked or dropped off leaving on the normal ultra blue of the LED shining through. The fix with these is to replace the backlight LED strips. I assume this will became a main topic on this sight in about 20 years??

Here are a few picture of Terry and myself working through these.

60 Backlight1
60 Backlight21
49 Backlight1
Terry1
Me1

The two old boys seen here are the last "Electronic" Engineers left at Sky, 60+ and 70+. Most of the work we do is power supply related, Terry doing most of the bench work and me joining in when things get a bit difficult. I spend a lot of time on UHD systems, Studios, MCR and TX. I also look after the station r.f. distribution systems and the Satellite dishes and their controllers.

Going back to the LG LCD Televisions I think we have about 8 left to do so nearly there. Yes my fingers get a bit sore.

Tomorrow it is back to the 1/2 inch tape cleaner rebuilt. Just got to calibrate the CCD sensor so it detects tape creases properly then Wednesday back to the backlight replacements.

Enjoy

 
Posted : 12/02/2024 2:23 pm
Alex728, Lloyd, Jayceebee and 1 people reacted
Jayceebee
(@jayceebee)
Posts: 2010
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No stranger to repairing LCD panels, all parts available for spares with Sharp TVs where the CCFL tubes being a common problem. The first signs were set would start but with odd colour then after a minute or so it would gradually become normal, later as they aged further the tubes would start but the backlight would shut down as the CPU would detect the current drawn was outside of tolerance.  I left the trade in 2011 just after LED backlights were introduced and were seeing problems early on then but not for the colour issues. 

I repaired a 43" LG a couple of years ago for a friend and was shocked just how thin the actual LCD matrix had become. Did the job on my own but wouldn't recommend it, the amount of flex it had i was sure it was going to crack. If anyone hasn't seen the effect I've attached a pic.

A neighbour a few doors away gave a knock a few days ago and asked if I would look at a set he had. Called round later that day, knocked and entered his lounge. TV was on had the same fault but not quite as bad. "Aha, the LEDs in your screen are failing I said" "What do you mean?" He said. "The faulty set is in the bedroom". He hadn't noticed the pronounced lack of green🤣. Thankfully he still had some warranty left.

before

John.

 
Posted : 12/02/2024 7:59 pm
ntscuser reacted
irob2345
(@irob2345)
Posts: 523
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Where I work we build network-connected information display units for public transport applications.

The LCD modules are gradually being supplanted by OLED modules. These display modules are about 4mm thick and of course require no backlight drivers. But LVDS as an interface has now gone.

Suspect this will keep me busy for a while, updating the PCB designs!

 
Posted : 13/02/2024 7:51 am
slidertogrid
(@slidertogrid)
Posts: 938
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I used to regularly travel to Paris and Amsterdam with XXJet I remember they updated all the check in desks and put a flat screen over each desk providing information. These screens displayed a predominantly orange display or background. Within a few years the displays looked terrible with the edges of the screens showing wrong colours some were worse than others with flickering and black areas. I suppose they had worn out, probably not designed for continuous use? They were eventually replaced with later gen screens which were much brighter and better definition. 

I am pleased to say I got out of the trade in late 2K before many flat screens were around! I repaired a couple for friends and neighbours in the early days. I didn't realise the later sets were even repairable. 

 
Posted : 13/02/2024 3:03 pm
Cathovisor
(@cathovisor)
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@irob2345 OLEDs can 'burn', strangely. Have a panel at work that has done it - the odd thing is that it burned 'positively'.

 
Posted : 13/02/2024 5:25 pm
Hurty
(@hurty)
Posts: 99
Estimable Member Registered
Topic starter
 

Hi irob2345, That is bad news replacing LCD sets with OLED sets!! OLED displays "burn" very quickly. Most illuminated LEDs go dim with time when they are on. Where I work they put up a load of OLED sets with permanent graphic displays on them and others displaying multiviewer outputs. 6 months down the line these have permanent images burnt into them. They came to do our area and most of these are again multiviewer displays so I had them all returned to be replaced with LCD sets except one which I use for the UHD channels. This shows off air pictures and is turned off when not needed. In the Master Control area we use Sony BVM-X300 monitors costing £30,000. These are OLED and after 3 years have now got burnt screens, predominately bars! It is £20,000 to replace the OLED screen. The new range of Sony Broadcast Monitors are now LCD with active matrix back lights, there is one on my desk, and these are what I recommend to use now. OLEDs are just bad news and in areas like Sky News and Sky Sports News the OLEDs burnt within a couple of years! Worst still was all the Calrec Apollo sound desks had OLED displays within the control panels and these burnt within a year and had to be updated with LCD displays and the same again with Wohler audio units which had two OLED displays on them, one for picture or data and the other showing sound level meters and yes they burnt extremely quickly and had to be updated to LCD displays.

If you purchase a new TV then the best pictures are indeed the OLED sets but if you predominately watch news or sports programs or anything witch a permanent logo then stick with LCD sets. You have been warned.

 
Posted : 14/02/2024 7:02 am
Nuvistor
(@nuvistor)
Posts: 4567
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@hurty Thanks for that insight, I know nothing about flat screen technology so it’s some more information in the memory.

My TV is a 2005/6 Sony 32 inch LCD it works ok at the moment but realise its getting on and will need replacing some day. After saying that I came to watch it a couple of day ago,  realised it was not plugged into the power socket, I unplugged it in the middle of January for some reason and not needed it since then. I am not an avid TV watcher.

 

i don’t know what I did to change the font size

Frank

 
Posted : 14/02/2024 7:16 am
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