A LCD screen repair: popped capacitors

A LCD screen repair: popped capacitors

Electrolytic capacitors are famous for failing when you are subjected to long time use, temperature and stress, swelling and popping the top where free part of the liquid electrolyte inside. Many motherboards from old computers that had this type of capacitors ended up failing within the year, and are now replaced by capacitors electrolytic aluminum polymer, resistant and more durable.

Important: before throwing a trash screen because you think that it doesn't repair, asks before budget in an electronic shop, may be little (every day they are cheaper and sometimes costs more to repair them, but provided that not worth more than a new repair, it is convenient to repair them, you are recycling, generating less waste and investing in hand of local work).

In this case left me a screen which the two seconds turning on lamps emitting a sound similar to a very low hum "zzzzz", is turned off. The sound was probably the vibration of the capacitors in the stage of transformation at the frequency of 50 Hz which is the AC, which emitted the sound to be in poor condition.

Danger, high voltage: the screen inverter much amplifies the voltage so it is dangerous, always walk with care, and although the circuit is not powered, keep in mind that you can have energy stored in capacitors and transformers, which in case of touch, can give you a good scare.

Replacing capacitors bloated
As you can see in the following image, 6 capacitors in the stage of transformation and investment to feed the 4 lamps of this screen were traps, so before looking nothing more, changed them by others of the same capacity (470 uF) value or something higher (not more than 40% more or could not do well their work); important to respect the voltage and never put other new capacitor of less voltage than requests (but can be of higher voltage).
What values to choose? It is important to respect the capacity (uF), the voltage can be increased but never less. There are times we fail the of same value (uF) and voltage; in that case try to put the same uF and higher voltage (even will endure better use), and if not, slightly higher capacity (up to 40% more there is usually no problem). We can also make such as batteries (not more than very small rechargeable batteries), build one of the capacity and voltage necessary combining several in series or in parallel; If we put them in series to find total capacity must add capabilities and divide by the number of items, and the voltage is added each one (always put the same voltages in series). If you put them in parallel then you must add capacity and voltage will be the lesser of the components. Differences between series and parallel.

To remove what I do is, with a soldering of 40W minimum, heat one of the connections of the two having capacitor and pull slightly on that side, then heat the other leg until the Tin is fluid, and proceed the same way with the other side. Do not use too much because we cannot stand with the capacitor in the hand and the leg still on the plate, although we can then remove it with a pair of pliers and heating the solder well. So I do, but if you do it often buy a balloon desestanador ex.
Notice before removing the capacitor if coincides with the serigraphy of the plaque marking if this was wrong (ever has already happened).

I changed the damaged and then replaced the circuit in place, with the good luck that when tested the screen came to life working perfectly. Luckily no other element was damaged. The I left a few hours turned on to check that everything was ok, and gave back it to its owner.

Opening the screen
To disassemble the screen (a Hannsfree) I let go all the back screws,

making your site stand then and making use of a screwdriver or knife to pry, go by separating the front cover grey, and view all the internal components. Raise the LCD display to access the stage of transformation and inverter which feeds the lamps, and after loosening the screws and cables in lamps,

We let the data cable by carefully pulling (there are different types Strip connectors, some require removing a CAP to release it, in this case the image is going to pressure simply):

And lifting can access the damaged part to loosen a few screws and separate the piece from the side connector to the Board which is responsible for the process of the image received by the VGA; in the image already with the hole where it was the piece that we have repaired:

And that's all for today! Happy repairs!