Repairing a Samsung 940N with a blinking power light.

February 26, 2012 by
Filed under: Uncategorized 

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:
Phillips screwdriver
Soldering iron
Lead free solder
Desolder wick
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.

We sell a repair kit with all of the proper value and size capacitors for $14.00 if you don’t want to worry about getting the correct parts.

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!


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Comments

8 Comments on Repairing a Samsung 940N with a blinking power light.

  1. Randall on Tue, 13th Mar 2012 5:49 pm
  2. This guide was perfect. I have a working monitor now.
    Employer is very happy!

    Cheers

  3. Rich from Australia on Thu, 12th Jul 2012 10:57 pm
  4. My 6 year old 19 inch Samsung LCD monitor died a few days ago and I was expecting to be paying up big for a new one…Ok , I can get a nice new 24 inch for a couple of hundred but being a compulsive fixer I managed to rip off the back panel and expose the PSU . Inside there was one swollen capacitor ! After searching my junk for a 470 mfd 25 volt all I could find was an unused 1000 mfd. Thinks me..too much of a risk , get back on the net and do some research !
    Googled the Bizet-17 power supply and got to your website and there’s my monitor !
    Cool…different model number ( mine is a Samsung 930BF ) but the inverter psu is identical.
    Learned something new about electrolytic caps …Low ESR !
    Thanks mate ! but too far away to order your repair kit . Found a local supplier and got all six caps for six dollars .
    Warmed up the soldering iron and got to work and changed ‘em.
    Put the beast back together and “hey presto” it worked……..well …sort of ?
    The picture did some strange psychedelics occasionally and there was a faint but annoying buzzing sound coming from within and then total blackness !
    Back to the drawing board !
    Pulled the monitor apart ..again ! Got out the Fluke and looked for shorted caps etc. Nuthing … Moving toward the garbage I noticed there was a different color on one of the little four pin plugs where the CCFL tubes are connected .
    Eureka ! there it was ! … One of the high voltage pins had failed …due to my hurrying it must have bent when I re inserted it and it arced out. !!
    Expecting all was lost as a new connector would be unobtainable I soldered some hookup wire between the pink wire and the circuit board , making sure everything was well sleeved and safe.
    Anyhow, to cut a long story short…it worked ! I still using my old piece of junk and it only cost me 6 dollars and probably 10 hours of my time ……….now if I was out working in my Air conditioning business I’d make about $70 bucks an hour so that means my monitor is worth $700 plus what it cost to buy in the first place and I really do want a nice new 24 inch screen……….It makes me want to cry !

    Regards Richy

  5. Asemota on Thu, 17th Jan 2013 1:36 am
  6. I encountered the same problem too when a friend brought his 940N monitor to me for repairs. When I openned the unit, I saw three swollen capacitors. But do I need to change the remaining capacitors since they are not damaged? And for the swollen ones, they are of the same ratings: 820uF 25v.

  7. in8sworld on Thu, 17th Jan 2013 12:51 pm
  8. Not really, in my opinion. The one’s that blew in my monitor were the one’s that take the brunt of the surge when the monitor is turned on or off so those are the only ones to worry about for me really.

  9. elktronic on Fri, 25th Jan 2013 9:08 am
  10. I tried to repair the Samsung 920N monitor with Power Supply Board BN44-00123A. When I opened it, I found a leaky capacitor 470-25V.
    I replaced all 6 capacitors but with no result.
    LED light turns on and from Power Supply Board comes the clicking sound but the screen is black.
    What else should I check or replace?

  11. CCL_TECH on Fri, 25th Jan 2013 1:13 pm
  12. Hello,

    What brand and series of capacitor did you use for the repair?

  13. elktronic on Wed, 30th Jan 2013 3:38 am
  14. 470 -25v jamicon TK
    47 – 25v jamicon TK
    1000 – 16/25v suncon WX

  15. Dedra on Mon, 22nd Oct 2018 1:33 pm
  16. Poor hunger or overeating. 1. Know His Landmarks.

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