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Posts: 6
Member Since: ‎05-20-2009
Message 1 of 17 (16,007 Views)

L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

Lucky you - You bought an L1906 Monitor from HP and one day all of a sudden, the Green Power LED just didn't turn on anymore. The Monitor appears to be dead!


Well I suspect it is because HP decided to save a few pennies by buying "second tier" electrolytic capacitors. You can read all about them on wikipedia, just look for "capacitor plague". In your monitor, several of them have burst, or are about to, and they have vomited the contents of their stomachs onto the PCB of your power converter. Mmmmm - yummy.

Not to worry. (A) For a "nominal" fee, the good folks at HP will gladly swap your monitor out for a replacement unit( with a few minor scratches).

Or (B) you can follow these handy steps to fix it yourself, while flipping HP a collective "bird", now and forevermore.

Personally, I went with option B.

Option B:

1) Face HP world headquarters and extend the middle finger of your right hand in salute, while uttering the words "BITE ME!" with menacing conviction.
2) Remove the power from your monitor and allow it to sit overnight so that all capacitors can discharge, thus making it safe to work on.


3) Insert a very small flat bladed screwdriver in the gap between the silver front bezel and the black plastic back (do this at the bottom of the monitor so if you scratch the bezel it will be less noticeable.)
4) Gently push the black plastic inwards which will deflect the black plastic retaining tabs inwards, and will release the silver bezel.
5) Once you have the bottom off, work up the sides and release the top. Then remove the bezel completely. Then unscrew the ON/OFF + Menu Button panel and move it aside being careful not damage the wires that attach it to the unit
6) Place the monitor face down on a towel (or other soft surface, for example a scantily clad super-model will also work)
7) Gently compress the top cap of the tilt stand to disengage the locking tabs that hold it on, and remove it revealing the "third screw" of the tilt mount. (I had to use a lot of 4-letter words to find this, your mileage should be considerably superior)
8) Unscrew the three screws holding the tilt stand to the monitor back and remove the tilt stand. These screws have loctite, so use a good screwdriver and press hard. If using a super-model, she should be squealing with each torque thrust.
9) Remove all 8 screws on the rear panel - 4 One in each corner, and four more on each corner of the raised section in the center of the monitor.
10) Remove the back cover
11) Remove the two screws on either side of the AC power receptacle and the 4 wires that plug into the monitor chassis, noting the order in which they are connected.
12) Remove the 4 screws that hold the LCD panel to the chassis
13) Gently remove the panel enough to get access to the power board, being careful not to damage any wires or their connection points.
14) Remove the 4 power board mounting screws, note that one is different, and remove the power board.
15) Remove all defective electrolytics (especially 5V 1000uF near the +5V outputs). The defective ones are bulged or have burst.
16) Mutter expletives under you breath. If young children are present, alternate "Darn!" and "Fudge!"
17) Clean off the HCl residue left by the burst electrolytic using board wash or 99% ISOPROPYL.
18) Replace the defective electrolytic capacitors. In fact, just replace all of them, that way this will be your final repair on this POS.
19) Suppress your anger.
20) Re-assemble and test.

Please post your repair experience on this thread. If you have any sentiments that you would like to express to HP, please use this forum as a place to indulge in an immersive catharsis. Feel free to vent from the orifice of your preference.

The capacitors did.

Posts: 1
Member Since: ‎06-01-2009
Message 2 of 17 (15,883 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

Hey, Thanks a ton! This is exactly the problem I am having. However there is one problem. I just CANNOT for the LIFE OF ME figure out how to open my L1906 monitor. I have removed all 4 corner screws and 4 center screws, and it will not budge. I have unscrewed everything possible. I noticed on the bottom left side there is a little slot with a picture of a Lock containing a K inside, do I need to unlock it somehow? How would I do that? Please Help.


Also, what type of Capacitors do I need to buy if I want to replace all of them? Thanks a ton! 

Posts: 6
Member Since: ‎05-20-2009
Message 3 of 17 (15,934 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

1) Aaron Dude!  Did you do steps 7 and 8? I am guessing NO! 


2) What about step 6?  What was the super model wearing?  What about step 1?  HP refused to replace the Monitor even though it was under warranty and I sent them photos of the defective parts vomiting the contents of their intestines onto the PCB; because they said I tampered with he product.  I'd like to tamper with them! (but I would settle for tampering with the super model, heh-heh)


3) They are the FedEx of the electronic component world. Here is what you need to know:

       Type: Low ESR Electrolytic

       Body: Radial

       Voltage: Whatever is written on the side of the ones you need to replace (the bulgy ones)

       Capacitance:  This is like how much beer can you hold before you have to, erm...void.   Only with electrons instead of beer.  It is also written on the side.  It is in microfarads.  uF.  The little u is pronounced "mu" as in "eeww" with an m in front.


4) Aaron, are you sure you are up for this?  In the next step, two things of varying badness can occur:


a) You could electrocute yourself on the larger capacitors, and possibly die (yes even when unplugged) or get some molten solder in your eye and

b) You could eff up the delicate wires connecting the various components together in your rush to unearth the power PCpack.


If you have any nerdy friends, maybe get them to help you.  Just offer them a PB or equivalent for payment.  Hell, just show them this letter.  That oughtta suffice.


OK Good luck.  Write back when you are not dead.  Crap, you got me worried now.   Also check out "capacitor plague" photos in Wikipedia so you know what to look for.




Top Student
Posts: 4
Member Since: ‎08-10-2009
Message 4 of 17 (15,617 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

I recently found this post from a search, followed the instructions and everything worked fine until today(it's been a little over a month since I did the fix).


The monitor just went out while using it. When I turned it back on, it flashed the screen for a moment, but turned back off. I took it apart and checked the caps, but they are all fine. I put it back together to test it, the screen flashes a couple of times, but won't stay on, even though the power will now. The caps I used are from Radio Shack. they meet the power reqs, but they are a little big for the case because of the 1 screw housing in the back of the monitor. This has caused the board to set a little uneven, but everything has worked fine up until today as I said before.


When the monitor is on now there is a noise coming from it, like a hissing sound from the area where the new caps are. I think think the problem now is due to the caps, being larger in size than the originals, has caused 1 of them to feel loose (when compared to the other new caps) and thus it's not quite connected as it should be. Any thoughts and ideas on this will be appreciated.

Posts: 6
Member Since: ‎05-20-2009
Message 5 of 17 (15,613 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

[ Edited ]

Hi fioantar10




First of all congratulations on the repair! It is difficult to do, you are to be commended!. Regarding the hissing, that could be arcing from the high voltage supply. It could also be the electrolyte cooking inside one of the Radio-Shack Capacitors, but you would smell it. Since you say that one of the capacitors is loose, it could also be a cold solder joint, or a defective capacitor, perhaps you are hearing arcing there, but again I doubt it. Try using your soldering iron to reflow the solder joints around the capacitor.  If it is still "loose" then replace it. That probably won't fix it, but let's rule that out. Also, you need to track down the hissing noise.  The part that is hissing needs to be replaced.  If you wiggle it and the hissing stops, it still needs to be replaced. I recommend that you wear rubber gloves since some parts of that board (the fluorescent supply) are high voltage.


  • Is the power light next tot he power switch green?  Orange?
  • Green all the time?  Flashing?
  • If you shine a flashlight onto the display, can you see the picture that is on the screen?


If so, then it sounds like the high voltage supply or the fluorescent part of the display are defective. For the fluorescent tube I think you can replace them, but it might not be worth the cost, please post here what you find out about that. Since it lights up and then craps our right away, I suspect the tube is fine. Probably some high voltage part in the HV supply is failing over once the HV is built up. Possibly a high voltage electrolytic. You will have to open up the supply. If I remember correctly it is inside a metal can.

The HV supply is wherever the HV wires that come from the display back plug into. I took a bunch of photos when I was inside, so if you get stuck write back and I will dig them up and try to point you in the right direction.


Remember: Safety first: Rubber gloves and as much as possible, keep one hand behind your back. That way no current can cross your chest, which could be fatal. If you use a volt meter, it must be a special high voltage type rated for 1000V (or use a high voltage probe) If you are not comfortable working with high voltage, then please do not proceed.


Also, use your sense of smell, just do not get too close.  I would normally recommend wearing a condom on your nose for safety, but that would prevent you from smelling, and also, your mom might freak if she came in the kitchen while you were, erm...sniffing.


Whatever happens, please post the result for the benefit or others.


Thanks and good luck



Message Edited by MorallyBankrupt on 08-10-2009 04:09 PM
Message Edited by MorallyBankrupt on 08-10-2009 04:11 PM
Top Student
Posts: 4
Member Since: ‎08-10-2009
Message 6 of 17 (15,563 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

Trying it again this morning, it now cycles off & on after pushing the power button. I can see it try to light up for about 3 seconds if I look closely, then it makes a brief, low scraping-hissing type noise (that's the best way I know to describe it), then it power-cycles and tries to start up again. If I push the power button, it will shut off & stay off until I push it again. The light is green when it is doing this, no other color.


I'm going to take a look at the other components as you suggested. I'll take some pics & I can post them or pm them this evening when I get home. I'll try resoldering that 1 cap & maybe replace it if that doesn't work just to rule it out. I think it would be better if I could find some smaller diameter caps as well, but the same power as the ones that are in there now. That would eliminate that 1 cap from pushing against the screw housing which is what I think loosened it to begin with.


Thanks for all of the advise. I'll be back later with updates. 

Posts: 6
Member Since: ‎05-20-2009
Message 7 of 17 (15,587 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

Hi Fioantar,


You can contact me on "hp dot forum dot gordjones at dfgh dot net"


Also, try not to do any more power ups until you have it open.  The hissing might stop when the partially failing component decides to become a permanently failing component, and then you will have a lot more difficulty locating the problem.  Also, what do you mean by "it power-cycles"?  Since the Green LED remains lit, I assume that you mean that the Florescent Display Backlight turns off then turns back on again. 


What is the voltage rating of the capacitor that is failing?


By the way, for future reference, Radio Shack is not the best choice for components.  And that is putting it kindly.  Try next time, you will not be disappointed.  Or, since you appear to be in SJ, you could go to Frys if you don't mind shoddy customer service, and being strip-searched when you leave the store.

Top Student
Posts: 4
Member Since: ‎08-10-2009
Message 8 of 17 (15,547 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

[ Edited ]

**POOF**  Smiley Mad


It stinks in here now...Smiley Sad


The little black (it was black before the **POOF**) object w/ the copper wrapped around the spool in the center of it is what went **POOF**

Message Edited by fioantar10 on 08-11-2009 10:18 AM
Posts: 6
Member Since: ‎05-20-2009
Message 9 of 17 (15,531 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

[ Edited ]

OK. Well I think we can safely conclude that it is a defective part. How many wires come out of it and what is the component designation on the printed circuit board silkscreen?


e.g. L1 or T3 etc.


Did you touch it when it went poof or did it go poof autonomously? Is the hissing sound gone?


Assuming "No" and "Yes" I am guessing that the switching inductor or flyback transformer toasted themselves as a result of dielectric breakdown. Could be easy to fix, assuming you can get the right part. Try to dust off the soot and see if there are any part numbers. Also, was this coil touching anything that it should not have been touching as a result of your repair? If yes, then it is possible that some of the insulation got displaced (it is just varnish) and that caused the failure. Also, any other sooted parts on the board now? Should be a big black diode (two wires, plastic case) near the coil. If you have a volt meter do this:




3) Measure voltage across the diode Should be 0V. If not, STOP.

4) Use "DIODE" Setting on meter (Symbol is a triangle with a bar normal to one vertex and centered on it.)

5) Apply leads to the two diode wires. Read the meter.

6) Switch the leads and do it again. Report both readings please.


Let's see if the diode is POOF too.


Also the switching transistor might be (is) poof. Black plastic case with three leads and will smell bad. May be attached to a heat sink (big block of metal with fins)  Again, we will need part numbers.


It is always difficult to put the smoke back into these components. That is why we should try not to let it escape in the first place. Some manufacturers coat their entire circuit packs with silicon sealer (called conformal coating) for this very reason, to prevent the smoke from coming out of the components.


By the way, if this terminal is still under warranty, this would be a good time to pack it back up, play dumb, and send it back to HP.


Also regarding FRYs, check Wikipedia under FRYs customer service. Hilarious! Reminiscent of HP Customer service!!!!

Message Edited by MorallyBankrupt on 08-11-2009 12:05 PM
Top Student
Posts: 5
Member Since: ‎08-11-2009
Message 10 of 17 (15,502 Views)

Re: L1906 Monitor - No Power FIX IT YOURSELF or Pay HP $$$ YOU DECIDE

If u got some $$$ buy SumSung or Sony L monitor, if u have no  $$$ you can get LG L-monitor for 130$ , fuk the HP, just say buy buy to HP in your LIFE, samething like DELL, ill spread the words for HP's Products, u guys just get rid of HP n buy new one.

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