14/08/2014

Change the lamp CCFL and inverter of a TFT screen

Change the lamp CCFL and inverter of a TFT screen


Over time (last between 5000-30000 hours), the lamp of the LCD and TFT screens tend to lose brightness, so it is good to change it; It is an element cheap but the cost of labor most of the times the screen pulls (if you have a damaged send it to me; price to negotiate;-).

Level modding:
Caution: The lamp works with 600V-2000V AC, danger of electric shock.
Cost lamp 2mm width: 10 euros + shipping (Ebay).
Cost inverter and transformer: used on a neon transformer to regulate the voltage approx. 15 euros. (Mod-pc)
Difficulty lamp change: 9 (1-10) only for the more trotters.
Difficulty changing transformer: 4For those who have basic knowledge of electricity.Time: 3 hours lamp and inverter, 1 hour only inverter.

Note: For those who only want to repair the lighting: Here you have a complementary tutorial of how to replace the inverter and with basic knowledge of electronics to a TFT/LCD display.
 

Some time ago left me a laptop for repair, used by connecting it to an external display, since the built-in screen made time that did not work. So I examined the components, and I decided to change both the lamp and the transformador-inversor.


Attention: in the vast majority of cases is the inverter which fails; you'll know because the lamp stops working suddenly, but image remains on the screen. Lamps rarely merge, what often happens is that they are losing intensity with the passage of time until you hardly see. In that case you can simply rename the inverter, with screens up to 19 "can be used one small used for personalization of the PC (modding) lights.
Change the bulb was extremely difficult, is encapsulated on one side of the LCD screen, so that the emitted light across the entire screen and illuminates it equally. It is also very fragile and the hollow where the cartridge goes with the same is extremely narrow, so I bought another spare.

It also must be careful to return to join the wires because if we do welding, high temperatures that reach the ends of the lamp can do is release the Tin, so usually are linked to pressure. Thanks to the ends of the original lamp stops I could deliver better temperature and refer you naturally to the rest of the screen.

To release the bezel from the display should find "buttons" of rubber or stickers that cover screws and can be removed with a razor or knife.

The loose screen resting on the keyboard of the computer


The back of the screen is protected by a sheet of aluminum


We can appreciate the inverter and lamp as loose after having removed the trim, using a precision Phillips screwdriver.


In this image subject damaged inverter laptop.
In this image we tested the new lamp bought from USA for 15 euros in total with unarmed inverter from computers and 5V DC neon light. The inverter converts it to 550V AC.


The lamp is suitably protected in a tube.


We can appreciate the fine which is the original lamp, protected by 2 elements heat at the ends.


The new lamp already settled back into its case of steel; It carries two jelly beans to keep the distance alike in its entirety with the deflector.
The transformer that I finally used to feed the inverter. As the output voltage changes we must regulate the brightness of the screen. It must take into account that higher brightness, shorter duration of the lamp.


At the end the placement of the lamp was not perfect as you can see by the most enlightened lower, however the screen can be used perfectly.


The final appearance with the subject for a little velcro transformer.

Notes:
The investor is making to "reverse" the phase of the input electricity; It takes Continuous current (CC) and transforms it into Alternating current (AC).
These portable and similar lamps tend to work with about 600-1500 volts and AC, and modding inverter usually work at 12V (check with a tester), as grab the CC that provides you with the power supply, and as you can see are quite compact.
These lamps consume very little, of the order of 5-10 Watts at full power (milliamps), anyway to feed them it is better to start to give them low voltage (always alternating current), as they simply turns very little, but not damaged.
It is would spoil (making the effect of a huge flash) If you suministrarais eg. 2000 Volt... and (I have not tried it) If you give it a CC is blow in milliseconds.

What to change?
Inverter (inverter) is what usually breaks down before, by the long duration of these lamps. If not alumbra nothing certainly is that.
But if you see that it has simply lost luminosity over time is to simply have will have exhausted the useful life of the lamp, so it will reach a point that it is better to change it.

If that happens to you is that the screen is white, then the lamps and inverter are perfect; It is failing to screen data cable, or the circuitry or own LCD (from highest to lowest probability).

Investors tend to take a system of protection; If the LCD has several lamps and detects that one is molten may turn off all (lighting a few seconds and then off). In this case it is convenient to check the lamps with a cheap inverter which are used for modding CCFL lamps, as I said.

In this store in the United Kingdom they have everything for repair of LCD screens, if anyone knows of any in Spain appreciate it indicated it me.


Parts of an investor

Inverter to 6 lamps


In an investor may fail anything, but the most common is that one of the transistors control damage. Also the flat fuse carrying near the power supply may fail, but if it fails it is because there is a problem so it would have to review it.
What is less likely to fail are low voltage to high voltage transformer coils. To check for high voltage, I have read in some Forum that approaching the high voltage transformer, a small neon bulb as the next image will illuminate partially if it is correct, no need for tester:



What are the CCFL lamps
Cold cathode fluorescent lamps do not need heat to be fully lit, are instant lamps working as fluorescent lamps, and are used where necessary a long life lamp, instant light and definite form, such as the lighting of the TFT and LCD screens, that are much used in modding.

Usually they contain some type of poison (mercury vapour) inside gas by what must be handled properly once their useful life. In alternative waste tanks will be in charge of them conveniently.