Dell monitor not working , green light blinks.
Capacitors look like cylinders mounted vertically on the pcb.
If you look at the printing on the board, there should be a label close to the capacitors such as C201, or XC330.
Usually a C in the label will indicate a capacitor.
They will be wrapped in a plastic jacket. The jacket will have writing on it, and usually a stripe down one side. The stripe indicates the negative lead (each cap will have two leads, negative and positive).
If the cap has a rounded top (domed) instead of a flat top, it is likely bad. You may even see that the component has split at the top, into four pie shaped wedges. This is also an indication of a bad cap. Lastly, the jacket is "heat shrunk" onto the metal cylinder. This usually causes the plastic jacket to overlap the top of the cylinder, which will show up as a donut shaped ring around the top of the cylinder. Some times if the cap is leaking, it will heat up causing the ring to shrink further so that the top of the cap will be completely exposed metal, with no plastic ring framing it. This also indicates a bad cap.
You can get the value from reading the print on the side of the cylinder. The values should be printed down the side of the cap, such as: 1000uF 16V, or 470uF 25V.
This is read as one thousand micro Farads at sixteen Volts, or four hundred seventy micro Farads at twenty five Volts (the u will actually be the Greek letter mu).
You will need a solder ****** to remove the solder from the caps on the solder side of the pcb (under $20), a soldering iron and some solder.
**** the solder after heating it with the iron, use the tip of the iron to carefully unbend the legs of the capacitors if needed.
Install the new caps making sure to observe the polarity. There will either be a mark in the board indicating where the negative lead should go, or a small + showing where the positive lead should go. Solder the leads and cut off the excess.
Make sure you get caps that are not larger physically than the originals or you may not be able to fit them into the same spot. (older capacitors are bigger than the same value newer capacitors).
Hopefully, you will only have three to six caps.
The lucky people will find only one bad cap, unlucky people will find up to ten bad caps, some in the power circuit, some in the inverter circuit, and some on the main board.
Caps on the main board can be very tough to remove. I recommend adding some solder to the legs of the caps you are going to remove, then heat one leg as you push the cap to the side to try and pull that leg out of the solder hole. Then heat the other leg and try to pull the cap completely off the pcb. Once done, you can use the solder ****** to clean the old solder out of the holes. This may be necessary because the main board is multilayer and these layers can act as a heat sink, making the solder harder to melt and harder for your solder ****** to remove. It's slightly easier once the capacitor legs have been removed.
Also note. Some manufacturers will use slightly larger caps, and in order to mount them they will bend the legs and glue the cap to the board on its side.
Mar 27, 2008 |
Dell E172FP 17" LCD Flat Panel Monitor