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    Re: Dell 2407WFPb Monitor - Bad Cap

    Schorsch87, take a look at the circuit diagram, post 387, page 20. The only way R603 would get fried is if the PWM module (IC601) has failed and became shorted pin 8 to pin 4. This has been occasionally reported here (e.g. post 384). If you are changing IC601, might as well change the other IC (651, the PFC). And make sure you have good resistance across Q651 (measure from D down to S).

    Comment


      Re: Dell 2407WFPb Monitor - Bad Cap

      balkeep,

      Your failure mode is similar to most other's here. The corrosion of C605 terminal causes it to disconnect. It is this disconnection that causes a cascading failure of circuit components. You managed to achieve that with a bad solder joint.

      R670 is 0.22 Ohm, 1 Watt.

      Whether IC651 can have 42 Ohms between some pins, I can't recall; it's possible. Check your Q651 with an ohmmeter, D to S. If it's short, assume that both IC's are toast as well.

      Comment


        Re: Dell 2407WFPb Monitor - Bad Cap

        Originally posted by pkanar View Post
        Schorsch87, take a look at the circuit diagram, post 387, page 20. The only way R603 would get fried is if the PWM module (IC601) has failed and became shorted pin 8 to pin 4. This has been occasionally reported here (e.g. post 384). If you are changing IC601, might as well change the other IC (651, the PFC). And make sure you have good resistance across Q651 (measure from D down to S).
        But I do not measure any shortcut on IC601 pins. And on IC651 I also do not measure shortcuts or the suggested 42Ohms. It's all in the kOhms range or above.
        But to be sure I ordered IC601 and will swap that one.

        C605 doesn't show any damage also Q651 doesn't measure a short. If it were shorted I can't measure the 310V over C605, am I right?

        Regards

        Comment


          Re: Dell 2407WFPb Monitor - Bad Cap

          Hey guys,

          I found the faulty component. IC651 was defective. Even if it is not shorted pin8 to pin4 it can by faulty.
          So I changed R603, IC651 and IC601 just in case.

          Thank you guys.

          kind regards and a happy new year

          Comment


            Re: Dell 2407WFPb Monitor - Bad Cap

            Can you guys please make an step by step guide on how to replace the power board with an AC adapter?

            Thank you very much!

            Comment


              Re: Dell 2407WFPb Monitor - Bad Cap

              Hello!

              My 2407 also gone these Days but its not only the screen is black or power dont turn on .
              I was working normal but then this little "boom" and the complete Power of the electric curcuit was gone. After checking the fuse box the fi switch and the circuit switch where off.
              So for now i am not able to connect the Power Cable from the Monitor to an electric Curcit without activating the saving switch in the fuse box.

              So first i am happy to found this Forum because i think this is exactly was i was searching for . i dont know anything about electronic but know someone if something have to be fixed.
              So first thing i found after some research in that thread is that R 670 is definitly gone. For the C605 i am not sure its a little bit corrosion but not that much as on other pics in this thread.
              Also theres an component called BD601 that have some white "fluid" clue left and right that is not that hard one so pherhabs this is also damaged.

              I also have made an Pic of the Board with the Connections because there are also capacitors that seemed to be damaged of what i read so far on the internet. They are lightly "arched" (dont know if this is the right word) on the top .
              All other Capacitors seems to have no damage on the sides or on Top.

              So first because theres no measurement possible because no connection to the electronic curcuit possible should i try to change R670 and C605 first and then if that works check all other components .Or is a measurement always working (as i said i know nothing about electronics) so i have to check my friend first so he can test everything ?

              Or do you think this Monitor is really Dead because the save electronic switch turn on ?

              PS.: I am from Austria so i dont know if some replacement are working in Europe because we have a different Power Supply System.
              Attached Files
              Last edited by Vitec; 01-31-2016, 11:44 AM.

              Comment


                Re: Dell 2407WFPb Monitor - Bad Cap

                Hello,

                I also have a no powering 2407WFP. As for many, leakage can be seen on the + PIN of C605, and a damaged R670. I also have a completely destroyed IC 651 (L6561 D) + R669.

                Don't know what caused IC 651 destruction, maybe a sudden voltage increase at the CS PIN which may also explain R670 and R669 destruction due to C605 failure.

                I have many LCD power boards, but none has a L6561D, each use a different IC for power factor correction. And there seems not to be PIN to PIN equivalency.

                Hope that after replacing all 4 parts, it will work again.

                Comment


                  Re: Dell 2407WFPb Monitor - Bad Cap

                  Originally posted by endor View Post
                  I take no credit for below - all cred goes to "Chris Colborne", can't recall where i found it.. fixya or something?
                  http://www.fixya.com/support/t152933...uff_smoke_dead in follow-up comments on his initial answer.

                  Comment


                    Re: Dell 2407WFPb Monitor - Bad Cap

                    I have a 2405 monitor with a 48.L1E02.A03 power board. Does anyone know if the 4H.L2K02.A01 E1 boards for the 2407 monitor are a drop in replacement?

                    I ask this as a quick BOM of likely failure components indicate that its cheaper to purchase the 4H.L2K02.A01 E1 board off ebay.

                    Comment


                      Re: Dell 2407WFPb Monitor - Bad Cap

                      I desided the broken 2407WFPb SMPS would be a great project to fix, since the great amount of information found at this forum and it's well documented PCB (thanks Dell!). It started as an small one-evening hobby project and turned out to be an 6-months on-waiting-for-parts-off experience. It has been an joyful experience however, which I am now typing looking at a fixed monitor. I would like to thanks all for the information provided.

                      Reading shortlist:
                      A special thanks to the following posts for their usefulness and/or high entertainment factor:

                      The fix:
                      Replaced both ICs together with the 'usual' suspects, making it the listing of:
                      • IC601 NCP1200D60
                      • IC651 L6561D
                      • ZD601 15V 0.5W Zener diode
                      • C605 RUBYCON KXW 120uf 450v 120mfd Capacitor
                      • F601 4A 250V Quick Fast Blow Glass Fuses Fuze
                      • R669 0.22 ohm 0R22 2Watt Metal Film Resistors 2W Resistor 1% #0680
                      • Q651 2SK3502
                      • Q654 2N3906S



                      Ordered them all on ebay.com, it took me roughly 4-6 weeks for items to arrive (based in The Netherlands):
                      • 100pairs OR 200PCS Transistor SOT-23 ( SMD ) 2N3904/2N3906 MMBT3904/MMBT3906 = 1.40
                      • 100PCS 4A 250V Quick Fast Blow Glass Fuses Fuze 5mmx20mm = 2.99
                      • 10pcs Panel Mount PCB Fuse Holder Case w Cover 5x20mm = 1.85
                      • 5PCS L6561D L6561 ST POWER FACTOR CORRECTOR SOP-8 SOP8 SMD TOP = 1.23
                      • 10pcs 2SK3502 K3502 N CHANNEL SILICON POWER MOSET TO-220 = 6.58
                      • 50PCS 0.22 ohm 0R22 2Watt Metal Film Resistors 2W Resistor 1% #0680 = 2.50
                      • 2pcs RUBYCON KXW 120uf 450v 120mfd Capacitor -40~105℃ 18*40mm = 6.99
                      • 5PCS 200D6 NCP1200D60 SOP8 IC = 3.62
                      • 1280Pcs 0805 SMD 64 Values 5% SMT Resistor Chips Assortment Kit 0ohm-10Mohm = 2.89
                      • 280Pcs 3V-39V ZMM SMD Zener Diode LL34 1206 14 Values 20pcs each Assortment kit = 3.15
                      • 100pairs OR 200PCS Transistor SOT-23 ( SMD ) 2N3904/2N3906 MMBT3904/MMBT3906 = 1.40


                      The total costs of my project was roughly 35 EUR/USD. I ordered multiple quantenties allowing me to kill a few and more importantly use them as reference measurements counterparts to find out if my board component was still working. If somebody based in The Netherlands, is looking for the components, feel free to send me a message to get my remaining stock sent.

                      Lessons learned:
                      • Reading the whole thread (multiple times) proved to be usefull and nessasary, yet an lengthy process, I hope the post will be a nice summery to success.
                      • If you are unsure with the logic-board and/or inverter board is still working, use the quick hack of AdrianM to first verify they are still working.
                      • Mind your safety, it are high voltages after all, use common sense and tricks like the 'bulb' test to limit the amount of fuses you have to replace. Always measure voltage over C605 ensuring it has dropped to a safe level, before handling the board.
                      • SMD soldering is a 'art', if possible use an SMD soldering station, a cheap one in the range of 100-150 EUR will do the trick over here, and/or go to your local MakerSpace to get help with soldering.
                      • Be careful when soldering, it is very easy to make solderjoints, re-test all new components before powering on. Also verify the the pads of the ICs are not floating. Put one test probe on the leg of the IC (near the black casing, not on the solder) and the other probe on the component it is connected to, use the famous 'beep test' to verify the path is made successfully.
                      • Test the board without the inverter board and logic-board attached. If successful attach the logic-board, you will now see output of by the LED of the power-button. The board itself will then consume roundabout 20W (easy to use with the light-bulb test). Mine was flicking and the board was making 'clicking sounds' after repair, this was fixed by soldering an floating IC leg, and cleaning the board with isopropanol one extra time to remove left-over soldering paste 'mess'.



                      Bonus:
                      Two of my buttons was broken (not responding any-more) aka the Menu & Plus button. To fix this; a) expose the button PCB b) for the affected tactile button peeled off the plastic of the button c) rotated the metal disk inside 45 degrees and d) put an piece of tape on it to hold it in place. Use the multimeter (resistor mode) to verify the pads are working fine again. Note there is a protective plastic cover of the back of the PCB, such that you need to apply some pressure (or remove the plastic) for the test pins to be reachable again.

                      Comment


                        Re: Dell 2407WFPb Monitor - Bad Cap

                        Originally posted by tgv View Post
                        Hello electronics experts,

                        I've got classic 2 seconds to black problem with my Dell 2407WFPb: on turning on, it goes black after a very brief display of whatever supposed to be on the screen; power button stays green.

                        There's no audible hiss or buzz, PSU and inverter boards look absolutely fine - no blown caps, no leaks, nothing visibly wrong but one thing: the tin cover that goes over inverter board has six rusty spots inside, just where the lamps are plugged in. Not sure if it's relevant -- photo attached.
                        Ok no electronic expert but this is the same problem my 2407WFP had i.e. every time I switched it on I got video for 1-2 seconds. Like you I replaced all the caps on the PSU but I also replaced the 120uF/450v cap. This cap on my PSU looked bad and I feel fortunate it didn't take out the PSU. Before I found this thread I had no plans to recap the PSU. I was looking at the top of the caps not the bottom so thank you for this thread!

                        My video board had several very slightly bulged 220uF/35v and 220uF/25v caps. Further more when I removed this board from the monitor I noticed the back of it had a yellowish stain around the mounting points. After removing all the caps on this board I'm wondering if this stain wasn't from leaked dielectric. Maybe I'm wrong but I found the same yellow stuff under some of the caps. Anyway I decided to replace all 29 caps on the video board. This fixed my monitor .

                        Here's a list of the parts I used:

                        12 x 493-1864-ND CAP ALUM 220UF 20% 35V RADIAL $.30ea
                        11 x 493-1547-ND CAP ALUM 47UF 20% 25V RADIAL $.22ea
                        6 x 493-10411-1-ND CAP ALUM 10UF 20% 35V RADIAL $.55ea

                        NOTE: Some of the 220uF caps on my board were 35v and some were 25v. I decided to use all 35v.

                        Comment


                          Re: Dell 2407WFPb Monitor - Bad Cap

                          Originally posted by gheoss View Post
                          Can you guys please make an step by step guide on how to replace the power board with an AC adapter?

                          Thank you very much!
                          I am interested in seeing this too. Seems like AdrianM tried to explain it, but his pics and explanation are too vague. My 2407WFPb still comes on, buttons work as usual, turns amber to green etc, but no display. It went from zero issues to suddenly no display after 11 years of trouble-free operation. Not sure if the PSU is bad or not, or if the inverter or ccfl's have gone bad. Although I am a good at soldering, I also see that this psu is only 12.99 brand new. You could replace it, get your monitor back up and running (assuming the psu is the problem) and then repair the old one as a backup.

                          I see no physical damage on my PSU, every component "appears" clean, but I know that means nothing. This makes me wonder though, especially since the front lights still work as usual. Hmmm, lol

                          Comment


                            Re: Dell 2407WFPb Monitor - Bad Cap

                            Originally posted by Mouse Trap View Post
                            My video board had several very slightly bulged 220uF/35v and 220uF/25v caps. Anyway I decided to replace all 29 caps on the video board. This fixed my monitor .

                            Here's a list of the parts I used:

                            12 x 493-1864-ND CAP ALUM 220UF 20% 35V RADIAL $.30ea
                            11 x 493-1547-ND CAP ALUM 47UF 20% 25V RADIAL $.22ea
                            6 x 493-10411-1-ND CAP ALUM 10UF 20% 35V RADIAL $.55ea

                            NOTE: Some of the 220uF caps on my board were 35v and some were 25v. I decided to use all 35v.
                            I plan on doing the exact same thing too. Since the LEDs still come on, and I have at least 4 or 5 caps badly bulged on the video board I have to assume this board is at fault.

                            However, if anyone could point me to a common list of suspect components to replace on the PSU I would highly appreciate it. I might as well solder on higher quality pieces while I have this monitor apart, right?

                            Comment


                              Re: Dell 2407WFPb Monitor - Bad Cap

                              Will these work for the large cap on the PSU? Are they even genuine Rubycons?

                              https://www.ebay.com/itm/141467570852

                              Comment


                                Re: Dell 2407WFPb Monitor - Bad Cap

                                I posted here a couple of years ago, my monitor was fixed after a helpful man from Utah sold me a working power board at a reduced price if I sent my broken one back to him.

                                Fast forward a few years and the monitor still works, but it seems to be gradually getting darker/yellowing and there is also some uniformity issues cropping up where a patch just to the left of the centre of the screen is slightly darker than the rest.

                                Is this likely to be the inverter board for the backlight, or could it be the backlight bulbs themselves which are failing?

                                The monitor is about 10 years old now so it has certainly been a good buy.

                                Comment


                                  Re: Dell 2407WFPb Monitor - Bad Cap

                                  Sounds like a dying CCFL to me, but I'm no expert. At $10 a pop per CCFL (guessing), if you can even find them I am not sure it is worth replacing 6 of them, and that's what you would need to do, probably. I still have not found a supplier for those. If not a CCFL, then the TCON maybe? I'm not sure how the Inverter board could cause anything but the entire screen to go dark, but not dark patches??? CCFL or TCON is my guesses, or maybe the main video board.

                                  My monitor is 11 years old now and just died a few months ago suddenly, with still a perfect picture moments before it went dark. Only the screen went dark, but all the LED's and buttons still do their normal thing. So therefor I believe only my PCB input board went bad as many of the caps are bloated and busted open. I have the new caps, but not the time yet to try a repair. If that fixes it, then I am going to pre-repair or replace my PSU just because. lol

                                  Anyway, I hope someone with further knowledge replies to you, because I have been waiting months for a reply... and well... lol

                                  Good luck!
                                  Last edited by SkOrPn; 12-20-2017, 01:21 AM.

                                  Comment


                                    Re: Dell 2407WFPb Monitor - Bad Cap

                                    Hello -

                                    I found this thread because I have the same problem with the OP, way back in 2011. And although this conversation has been kept alive for all these years, I am tempted to be the one to resurrect the old problem of repairing this DELL 2407WFPb monitor power supply.

                                    I am posting pictures of my PCB, it looks identical with the OP's and I have the following questions.

                                    #1. It appears the culprit is again corrosion on the positive terminal of the C605 capacitor (245V 120μF). However, the rest of my PCB and components seems to be in fine shape: No discoloration, no fried components, no corrosion on the solder joints, it looks like new. BUT ... is this only, a good indication that somehow the C605 just blew up (that's exactly what happened, it made a small bursting sound at power-up) so the left of the circuit was -luckily- left intact? What I mean is should I just replace the capacitor and see it it works or there is a chance something else went with the capacitor and if I power up I risk frying something else? I know this is a loaded question, but is there a basic/safe procedure to test the surrounding components and if yes please do not bother rewriting it just point me to the correct link.

                                    #2. I am not an electronics wizard, other than I am a musician who likes to tinker with tube amplifiers. So, I understand the C605 is a decoupling capacitor which helps smooth out AC ripple and to provide a steady DC on the output. Now I happen to have at hand a 200μF and a 100μF capacitor (both rated @ 500V) but not a 120μF at 450V. My feeling is that the 50V of tolerance is not a bad thing (actually it's better) but I am not sure if I should go with the lower or the higher value. The smaller value is closer to the original spec but my gut feeling tells me that I should go with the 200μF and that the 80μF more is actually going to be OK, but not if I go with a lower value even only by 20ΜF. What do you guys think?

                                    #3. If I try the capacitor and it does not work, then most likely I have more damage on the PCB so I am leaning towards finding a replacement board altogether (can be had on eBay for about $15 ... albeit from ...China). I think that will be better than troubleshooting each component separately, even though the quality of the board might not be top quality, my goal is to fix this asap and get it back on my desktop.

                                    So what do you guys think?

                                    Thank you all for all the advice so far (tried to read as much as I could) and for the follow up posts!

                                    Take care everybody!
                                    Attached Files

                                    Comment


                                      Re: Dell 2407WFPb Monitor - Bad Cap

                                      Yeah it looks like that Cap started leaking, but no telling for how long. You could try finding that cap but it might be easier to just buy the entire PSU for it. It's only $12.99 plus free shipping.

                                      Oh and I am not sure what you meant by "albeit from ...China", 100% of Dells PSU's come from China. By the way, your Cap is a Panasonic cap, so I am surprised it went bad. Mine had all Elite Caps.

                                      https://www.ebay.com/itm/ORIGINAL-Br...B/272410466809
                                      Last edited by SkOrPn; 02-22-2018, 06:43 PM.

                                      Comment


                                        Re: Dell 2407WFPb Monitor - Bad Cap

                                        Wow, didn't know these boards were this cheap!

                                        I think I'll order one, 5 years after initially finding this thread, deciding the powersupply board was beyond economical repair and having run the monitor since then on a laptop supply...
                                        Last edited by r-p; 02-26-2018, 04:01 PM.

                                        Comment


                                          Re: Dell 2407WFPb Monitor - Bad Cap

                                          Originally posted by r-p View Post
                                          Wow, didn't know these boards were this cheap!

                                          I think I'll order one, 5 years after initially finding this thread, deciding the powersupply board was beyond economical repair and having run the monitor since then on a laptop supply...
                                          Well then I am happy I mentioned it to you.

                                          I wish that was the problem with mine but I have 9 blown caps on the video board itself and yet it lasted from early 2006 until late 2017 before it went black screen. I can't find anything wrong with the PSU, all the tests show its still working. I got a Rubycon kit for it but I have not bothered to solder them in yet.

                                          Comment

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