Repairing a Samsung 940N with a blinking power light.
We have been getting more and more of these units in our service center with bad power supplies. If you have a 940N with a blinking power light and no display, is slow to show a picture, or has a wavy picture then this guide should help you get your monitor back going again. The most common power board used in this model is the Bizet-17 power supply board, also know as BN44-00123A. There is another board too, so check your board model number. We will post the parts detail on that board too. The typical problem with the monitor is a failure of capacitors on the power supply board. The repair is fairly easy, just requiring replacing 6 capacitors to bring the unit back to life.
The complete the repair you will need the following tools and parts:
Lead free solder
and the capacitor kit that contains the following:
qty(2) 1000uf 25v capacitors
qty(2) 1000uf 16v capacitors
qty(1) 470uf 25v capacitors
qty(1) 47f 50v capacitor
Be sure to use good quality low ESR, high ripple current, high temp capacitors or you can damage the power supply board. More information on getting the correct capacitors can be found on our capacitor page.
This is not guaranteed to solve all problems but in most cases this is the issue with this model.
If you don’t want to do the repair yourself, use the service request link. Most monitor repairs run $35-40 plus return shipping.
Be sure to check out our forums section where you can ask questions about this repair or find information about other topics.
Ok, the first thing to do is remove the power cable, video cable and monitor stand. Be sure all the screws shown circled below have been removed.
Next turn the unit over and grasp the front bezel. if you lift the bezel and flex it a bit the front will start separating, just work your way around the side until the front and back can be removed.
With the case removed you can to remove the RF shielding covers. The first cover to remove is on the left side and it covers the back light connectors, it is held in place by metal tabs. To remove it just pull the cover towards the end of the monitor and the first tabs will release so you can pull it off the other set of tabs. You will also need to remove the Panel control cable as shown on the upper right. This connector has release tabs on both sides that need to be squeezed to release it.
Under the RF shield cover you will find the back light plugs. Disconnect the four connections by squeezing the connector and pulling, they have a clip that has to be released before they will come off.
You will also need to disconnect the front panel control cable as seen here. It also has the clip so you will need to squeeze the connector to remove it.
You can now remove the RF shield cover and flip it over to access the power supply board as seen here. There should be three screws to remove and then unplug the power cable that plugs into the video drive board.
Now you can remove the power supply board to get it ready for the repair. The board is shown here with the problem capacitors circled. You will need to desolder the bad capacitors using the soldering iron and desolder wick. The capacitors have the value printed on the side so as you remove each one just insert the new one in its place. Also on the one side of the capacitor is a gray stripe, this is the negative side, on the board where the capacitor goes is a circle with one side shaded, this is the negative side. Insert the new capacitor with the negative lead going into the negative marked hole and then solder the connections.
After replacing the 6 capacitors just reassemble the monitor and test it, You should now have a fully functional monitor.
Post a comment below to let us know how your repair went!