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Dell 2407WFPb Monitor - Bad Cap

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    Re: Dell 2407WFPb Monitor - Bad Cap

    Originally posted by Tyan View Post
    thats mine, reading
    brown black orange yellow

    should be 10k ohm, mine has 9,85k
    many thanks Tyan. That was a great help.

    By the way, you did the resistance measurement onboard, right? what are the resistance value of R608 & R609 from your power board?

    I am suspecting something amiss because mine measured 600k (on board) for both the R608 & R609.

    Thanks again for your help. Appreciate it.

    Comment


      Re: Dell 2407WFPb Monitor - Bad Cap

      yes, measured on board.

      For the R608 & 609 i can´t tell a number, they show some "behavior". They started with ~500k rising, i stopped measuring at ~620k. Above 600k it rose by 3k, declined 2 and rose 3 again... both showed exactly the same behavior.

      Comment


        Re: Dell 2407WFPb Monitor - Bad Cap

        Originally posted by Tyan View Post
        yes, measured on board.

        For the R608 & 609 i can´t tell a number, they show some "behavior". They started with ~500k rising, i stopped measuring at ~620k. Above 600k it rose by 3k, declined 2 and rose 3 again... both showed exactly the same behavior.
        Thanks again Tyan.

        It seems my result is the same as yours. Ok then, i will replaced the burnt components first & will see how it goes.

        Comment


          Re: Dell 2407WFPb Monitor - Bad Cap

          HAHAHA i´m such an idiot

          can somebody tell me the specs of TR601? The round, green friend right next to the 4A Fuse? It seems it doesn´t like blue flashes very much. Has a nice, black crater now -.-

          edit:
          made a pic, see below. Sorry, this time mobile phone pic only.
          the green thing reads
          SCK
          056

          *sigh* this time i´ll ask the electric dept. at work if they can help me out with a spare one.
          Attached Files
          Last edited by Tyan; 10-10-2011, 11:57 AM.

          Comment


            Re: Dell 2407WFPb Monitor - Bad Cap

            Originally posted by Tyan View Post
            HAHAHA i´m such an idiot

            can somebody tell me the specs of TR601? The round, green friend right next to the 4A Fuse? It seems it doesn´t like blue flashes very much. Has a nice, black crater now -.-

            edit:
            made a pic, see below. Sorry, this time mobile phone pic only.
            the green thing reads
            SCK
            056

            *sigh* this time i´ll ask the electric dept. at work if they can help me out with a spare one.
            That's a NTC (negative temperature coefficient) thermistor made by THINKING ELECTRONIC INDUSTRIAL CO., LTD. It limits the inrush current when the monitor is first plugged in. SCK is the series, 056 is an abbreviated form of the part number. Unfortunately, their datasheets only show the full part number.

            PlainBill
            For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

            Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

            Comment


              Re: Dell 2407WFPb Monitor - Bad Cap

              Hi, I have sourced a L6561D for replacement in the SO-8 package, but I can't for the life of me determine which is pin 1. How do I tell?

              Comment


                Re: Dell 2407WFPb Monitor - Bad Cap

                Originally posted by sirzur View Post
                Hi, I have sourced a L6561D for replacement in the SO-8 package, but I can't for the life of me determine which is pin 1. How do I tell?
                Look at the datasheet. It will have a dot on it.

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                Comment


                  Re: Dell 2407WFPb Monitor - Bad Cap

                  I have looked at it through a magnifying glass with a bright LED light on the surface and I can't see any dot I can only assume that pin 1 is the bottom left when the words are the right side up

                  Comment


                    Re: Dell 2407WFPb Monitor - Bad Cap

                    Originally posted by sirzur View Post
                    I have looked at it through a magnifying glass with a bright LED light on the surface and I can't see any dot I can only assume that pin 1 is the bottom left when the words are the right side up
                    That is usually correct. There are other indications, however. Usually one end will have a notch. Another is a dimple by pin 1. A third is a chamfer (bevel) along one side of the IC.

                    PlainBill
                    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                    Comment


                      Re: Dell 2407WFPb Monitor - Bad Cap

                      I finally went by the bevel. Looked up the dimension of the SO-8 package and wikipedia showed the bevel. Pin 1 is on the bevel side, on the left

                      Comment


                        Re: Dell 2407WFPb Monitor - Bad Cap

                        Usually, one should be happy watching FIREWORKS up in the sky! The reverse can be said when you encounter it on the HV pin of an SMPS controller..

                        update.

                        Replaced the burnt R603 with a 10K ohms 0.5W (thanks Tyan for the resistor value). Also replaced the SMPS again & Q654 with PMBT2907 as stated in the Russian website mentioned by WillyBobz (See post #88) Plugged the monitor. Sparkle & FIREWORKS again occurred on the SMPS controller IC NCP1200D.............. With an aroma of magic SMOKE, to accompany it with.

                        In summary, the below were replaced.
                        Replaced both LD6561D & NCP1200D (twice & both caught fire), together with
                        1) C605 120uF/450V
                        2) Q651 with STP10NK60ZFP,
                        3) R669 1k ohms SMD
                        4) Q601 2SK3548
                        5) ZD601 15V 0.5W Zener diode
                        6) R623 4.7ohms (4R7) SMD
                        7) R670 & R615 (0.22ohms)
                        8) Q654 first with MMBT3906 then with PMBT2907, (on both occasion SMPS got burnt)
                        9) R603 10K ohms 0.5W

                        ... and still no joy..

                        So, do you guys think i have replaced any of the components wrongly causing the sparkles & fire? I have attached a schematic taken from the same Russian website in hoping that someone can point/lead me to where is the faulty component/s that is causing my 2 newly replaced IC to get burnt. The problem now is i can't even measure any voltage reading due to the fire, which i saw started at the HV pin (Pin 8) of the SMPS controller ( NCP1200D). I can only measure resistance, etc with power unplugged.
                        Attached Files
                        Last edited by newbie1; 10-19-2011, 10:17 AM.

                        Comment


                          Re: Dell 2407WFPb Monitor - Bad Cap

                          A huge thanks to CaScAdE for this. It resolved my issue. My buddy brought me a 2407wfp (not sure about the "b") and it appeared to have a dead inverter. But there were no burn marks, bad caps. Nothing. It didn't make any sense. I checked the other three fuses, but overlooked F1. Pulling F1 and testing it showed it was indeed open. I couldn't find a 2.0 amp fuse, so we shorted it out. The guy got the monitor for free and figured it was no big loss if it smoked it. It worked beautifully.

                          Thanks!

                          Originally posted by CaScAdE View Post
                          Hi there...
                          Since my WFP2407 stopped working yesterday and I have no service-tag (and the dealer I bought my display from is not doing anything regarding to PC-stuff anymore) I descided to open up my Display.

                          It was the F1 fuse that was broken (measured several M-Ohm inside the circuit over the fuse). So I searched through my boxes with stuff and found some old glass-fuses rated 2.5A. I did assume that the 2.0 on the fuse stands for 2.0A so 2.5A was close enough for me to test.

                          The Fuse with some wires soldered to it:


                          The replacement Fuse:


                          After the usual seconds of doubt I plugged in the device and got the DELL-Logo, it was alive again! Nice...

                          Since I cannot get my hands on a 2.0A SMD-Fuse currently I decided to just clean up the stuff I did a bit and repack my Display until I get a nicer fuse.

                          A bit nicer:


                          I think I will try to get my hands on
                          BOURNS - SF-1206S200-2 - FUSE, SMD, 1206, 2A
                          since the dimension fits, it is a slow fuse and rated 2.0A. But the minimum order value at Farnell (and resellers for private persons) keeps me off from testing it right now.

                          Maybe someone gets here via google (just like me) and gets motivated by the pictures

                          Regards

                          Comment


                            Re: Dell 2407WFPb Monitor - Bad Cap

                            Originally posted by newbie1 View Post
                            Usually, one should be happy watching FIREWORKS up in the sky! The reverse can be said when you encounter it on the HV pin of an SMPS controller..

                            update.

                            Replaced the burnt R603 with a 10K ohms 0.5W (thanks Tyan for the resistor value). Also replaced the SMPS again & Q654 with PMBT2907 as stated in the Russian website mentioned by WillyBobz (See post #88) Plugged the monitor. Sparkle & FIREWORKS again occurred on the SMPS controller IC NCP1200D.............. With an aroma of magic SMOKE, to accompany it with.

                            In summary, the below were replaced.
                            Replaced both LD6561D & NCP1200D (twice & both caught fire), together with
                            1) C605 120uF/450V
                            2) Q651 with STP10NK60ZFP,
                            3) R669 1k ohms SMD
                            4) Q601 2SK3548
                            5) ZD601 15V 0.5W Zener diode
                            6) R623 4.7ohms (4R7) SMD
                            7) R670 & R615 (0.22ohms)
                            8) Q654 first with MMBT3906 then with PMBT2907, (on both occasion SMPS got burnt)
                            9) R603 10K ohms 0.5W

                            ... and still no joy..

                            So, do you guys think i have replaced any of the components wrongly causing the sparkles & fire? I have attached a schematic taken from the same Russian website in hoping that someone can point/lead me to where is the faulty component/s that is causing my 2 newly replaced IC to get burnt. The problem now is i can't even measure any voltage reading due to the fire, which i saw started at the HV pin (Pin 8) of the SMPS controller ( NCP1200D). I can only measure resistance, etc with power unplugged.
                            I decided to disconnect the rest of the boards & leave the power plugged on its own. Upon plugging (turning on) the power, saw few small sparks on the SMPS controller IC, but i decide to leave it ON. Then suddenly a gush of fire erupted & the NEWLY replaced R603 10K ohms 0.5W got burnt badly. The PCB board was also charredas well.I am still looking for the faulty component that is drawing high current (transistor, capacitors, or transfomer?). Can it be the transfomer? Appreciate if some experts here can shed some light.

                            BTW, is Dell 2408wfp panel swappable with 2407wfp?

                            Comment


                              Re: Dell 2407WFPb Monitor - Bad Cap

                              Originally posted by newbie1 View Post
                              Thanks PlainBill!. Splendid website!!.. I wish i could say the same for my current repair though.

                              Update. Replaced the shorted SOT23 diode with a MMBT3906 (PDF attached). No joy! I measured 330V across the Big cap. But NO voltage output to the other card (Logic or inverter). I will TRY to flip over & measure voltages on the NCP1200D & L6565D (PDFs attached). If anybody could point out which particular pins on them i should be focusing on, that would be great!.



                              Tyan, may i know how do you tell it is toast? Visually, I can't see anything wrong with it. But i do not have a capacitance measurement to measure it though.
                              SOT23 is is a diode? Very thankful with PlainBill for the SMD info!

                              Comment


                                Re: Dell 2407WFPb Monitor - Bad Cap

                                Originally posted by endor View Post
                                hi,

                                I found this info regarding the power board for a 2405
                                I think it is the same or very similar board in the 2407.

                                I take no credit for below - all cred goes to "Chris Colborne", can't recall where i found it.. fixya or something?


                                ************************************************

                                Repair of DELL 2405FPW monitor, was completely dead. Power Supply Board 48.L1E02.A02 repair successfully completed 27th May 2010.
                                IMPORTANT DISCLAIMER:
                                Every effort has been made to avoid errors in my report but I accept no responsibility for any loss or damage resulting from any inaccuracies in it.
                                Contents:
                                1) Summary.
                                2) How to open the case. (The basic principles apply to many other models)
                                3) Fault-finding and repair of the power supply board, in my particular case.
                                4) replacement components list
                                5) How to quickly tell whether you suffered the same faulty component(s) as me.
                                1) I'm not an expert in monitor repair or switch-mode power supply repair. However I managed to completely cure what turned out to be multiple failures on the power supply board. I replaced several obviously damaged components but did not get it to work. However, I was fortunate to have access to an identical working monitor to compare it with, taking meter readings of resistance, capacitance and diode voltage drops (as appropriate) all over the boards, spotting any differences and tracking them down to specific components. Once all the faulty components had been identified and replaced, the whole thing burst into life! You may not have the luxury of a good board to compare it with, but hopefully what I found out about mine will be useful to you.
                                NOTE: at no time was it necessary to have the inner metal covers removed while power was connected. No matter how careful you are there is always the chance of a slip-up when hazardhous voltages are exposed - this risk was completely eliminated by doing all probing of the circuit dead (not always possible, but always desirable!) and re-fitting the protective earth lead and putting the metal cover back on with just a couple of screws each time I tried it out. It added only seconds to the time taken to do the job.
                                2) To open the case: first prepare a clean, clear area of bench to work on. A cluttered bench could result in damage to the screen when you lay it flat on its front!
                                a) unclip the panel from its stand and remove the four screws in the center that usually hide behind the VESA Mount.
                                b) stand the panel upright on the bench on its bottom edge. Using your fingertips prize the front bezel (plastic frame) forward from the glass, but without putting excessive pressure on the glass. It should come away with a series of 'snaps' as it releases from the back section of the plastic case. Proceed all the way around the screen detaching the bezel from the back. You do not need to completely remove the front bezel as it is connected at the bottom with a ribbon cable to carry the signals for the buttons and LEDs and this cable must not be stressed.
                                c) The back section of the case, together with the silver portion (which is screwed to it) can now be completely removed and the panel laid face down on the bench, resting in its bezel. Do not lose the little mounting release button which is now free too fall out of the back of the Vesa mounting in the case!
                                d) Now we see all the metal covers hiding the various subsystems of the monitor. With the bottom of the screen towards you on the bench, the driver for the backlight is readily accessed by removing the four screws holding down the shiny cover on the left. But I wasn't after that.
                                e) to access the power supply and system board you first have to remove the shiny cover over the memory card reader/USB hub on the right. Remove the single screw on the top left of it. While gently lifting the two little clips at the extreme right-hand edge, slide the shiny cover to the right to release it from the main panel chassis.
                                f) Now you should be able to access all six screws holding the central metal cover on. Remove the screws and simply lift the cover upwards to expose the PSU and system boards.
                                g) To remove the power supply board: Note the position of the little black plastic clip retaining the power inlet connector before removing it. Disconnect the two multi-way cable looms from the system board (right) and backlight inverter board (left, top). NOTE: The looms do NOT detach from the power supply board! Remove the three screws from the corners of the power supply board (note these are the ones with very broad heads) and the big shiny screw tying the protective earth lead to the chassis. The PCB is now only held in place with a little white plastic clincher near the middle which needs both sides to be squeezed before the board can be lifted clear.
                                3) Faultfinding and Repair
                                a) The first thing worth looking at when working blind on a failed switch-mode power supply is the large, high voltage electrolytic capacitor. In this case, it's C605, value 120uF, 450V. Sure enough, with the meter set on capacitance there was no reading - dead capacitor. I used the most readily available alternative, which was a different physical size but still fits within the cover.
                                b) Near the mains inlet is F601, a 4A, 20mm, antisurge ceramic fuse (T4A H). Inevitably this was blown. Since it had solder leads to the board, I replaced it with a fuse holder with overall insulation, fully anticipating I would get through a few fuses before getting the right result - but in the event this did not happen. The pin spacing on the board is 25mm (1 inch) so I had to slightly spread the pins of the fuse holder which was designed for 22.6mm centres.
                                c) Visual inspection of the underside (surface mount side) of the board revealed a charred integrated circuit IC651. However enough of it was left to read the part number, L6561D. This was replaced. Nearby, R669 was also burnt, It is an 0805 size, 1Kilohm resistor. I replaced it with a higher power, 1206 size one for good measure.
                                d) there was no other visible evidence of damage so I put it back on the monitor, connected the two output looms and earth wire, fitted the metal cover with 3 screws and powered it up - Still completely dead.
                                e) Probing resistance across the terminals of all the large transistor-type devices I found a very low resistance across Q651, indicating a failure. Using Famous Windows Search Engine on the case marking, This was identified as a MOSFET of type 10NK60, readily available. Test: still dead!
                                f) Probing diode drops and resitance around the two boards I discovered an anomaly around ZD601 (a diode in a MELF-like surface mount package) which appeared to resemble a 22-ohm resistor! I removed the one from the good board and with a suitable test circuit found it to be a 15V Zener Diode. Replaced the faulty one (with a leaded device fited to the smd pads) but there was still an anomaly in this general area of the board, see next paragraph:
                                g) Probing capacitance around the electrolytics on the two boards I found that the capacitance measured at C611 (a 47uF, 35V electrolytic capacitor on the Top side) was 47uF on the good board but 68uF on the bad board. I removed the capacitor but it was found to be OK reading 47uF by itself. The positive lead goes to pin 6 of IC601. WHen I lifted this pin the measurement dropped to the proper value, indicating that IC601 was the next faulty device to change. This was hard to identify but again using a FWSE on the case marking "200A6" found it was in fact a PWM driver for standby power applications, readily available. Replaced this: And the job is done!
                                New components list (all replacing definitely dead parts) all purchased from Farnell Electronic Components, but equivalents should be available from any major distributor.
                                a) F601 T4A HBC fuse, FEC code 135-4592 (in a plastic shrouded holder, FEC code 976-120)
                                b) C605 120uF/450V electrolytic capacitor, snap-in, FEC code 178-2697, £3.12 (Not same dimensions as the original, but made to fit with extended leads!)
                                c) Q651 STP10NK60ZFP, Zener protected N-channel MOSFET, TO-220, FEC code 993-5517, £1.31
                                d) IC651 L6561D, Power Factor Corrector IC, SO-8, FEC code 988-2464, £0.79
                                e) R669 1k 1206 (commodity item) soldered onto 0805 pads
                                f) ZD601 15V 0.5W Zener diode (commodity item) soldered onto SMD pads
                                g) IC601 NCP1200D, PWM controller for low-power off-line supplies (original was NCP1200A), SO-8, FEC code 165-2430, £0.91
                                How to quickly tell if yours suffered the same fault(s) as mine, armed only with a multimeter (including capacitance reading):
                                a) F601: Resistance of fuse high!
                                b) C605: Capacitance reading not correct
                                c) Q651: Resistance only a few ohms between one pair of pins
                                d) IC651: visibly burnt
                                e) R669: visibly burnt/ resistance no longer 1k
                                f) ZD601: resistance of about 22R across it, both ways round?
                                g) IC601: Capacitance measured across C611 appears more than 47uF even though C611 is OK.
                                Reassembly is the reverse of dismantling. Connect all cables, especially ensure the safety erth lead is tightly screwed to the chassis. Fit the other three screws (with extra wide heads) to hols the Power Supply board in. Fit the black plastic clip over the top of the mains inlet - it only fits on way round.
                                Chris Colborne (Senior Electronics Technician, Diamond Light Source Ltd, Didcot, Oxon, United Kingdom).
                                www.diamond.ac.uk
                                At the moment i'm trying to find L6561D & NCP1200A in local store, I did have a DIP L6561 w/c i'm planning to solder with the help of wire jumpers. Im not sure if i could find mmbt3906 if none the 2N3906 would be handy again using jumpers.

                                With the above troubleshooting guidelines followed and nothing happens, what would seems to be the problem?

                                Once i acquired all the above necessary parts I'm going to start soldering them all.

                                I'll get to you soon and give you whatever result i got.

                                thanks, this is very informative!

                                Comment


                                  Re: Dell 2407WFPb Monitor - Bad Cap

                                  Originally posted by regino3rd@yahoo.com View Post
                                  SOT23 is is a diode? Very thankful with PlainBill for the SMD info!
                                  Let's be precise in our terminology. SOT-23 is an SMD package. It usually contains a transistor, but can contain a diode, pair of diodes, zener diode, hall effect switch, or voltage reference. Heck, it could even contain a (very low power) voltage regulator!

                                  It is important to look at the component designator. Q101 would be a transistor; D101 would be a diode; ZD101 would be a zener diode.

                                  PlainBill
                                  For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                                  Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                                  Comment


                                    Re: Dell 2407WFPb Monitor - Bad Cap

                                    Originally posted by WillyBobz View Post
                                    Hi NZROSSI,

                                    Many thank's for coming back to me with that information, with your instructions I was able to place my order (170RMB) $37.13 first payment, then International shipping fees on second payment. I just could not quite grasp their instructions!
                                    I am really greatfull for your help/advice, it is a great site and source for valuable information. I will post my reults in due course, fingers crossed!
                                    Hi, Well.......... It finally came (4H.L2K02.A01), used PSU from China, upon close inspection I noticed that Diode 665 was shot (physically cracked and broken up), I replaced this with the component from my "Faulty Board", also changed C605 (which is the instigator of all the problems) with a QUALITY slightly larger diameter one, plugged in and *****Hey Presto!!!!***** Back up and running, this board was obtained from Chinese E-bay through and English speaking Agent (Taobao Focus), there are still some available, so don't give in! These monitors are FAR TOO GOOD to end up on the tip! My thank's to all on this forum especially NZ Rossi.

                                    Comment


                                      Re: Dell 2407WFPb Monitor - Bad Cap

                                      Originally posted by WillyBobz View Post
                                      Hi, Well.......... It finally came (4H.L2K02.A01), used PSU from China, upon close inspection I noticed that Diode 665 was shot (physically cracked and broken up), I replaced this with the component from my "Faulty Board", also changed C605 (which is the instigator of all the problems) with a QUALITY slightly larger diameter one, plugged in and *****Hey Presto!!!!***** Back up and running, this board was obtained from Chinese E-bay through and English speaking Agent (Taobao Focus), there are still some available, so don't give in! These monitors are FAR TOO GOOD to end up on the tip! My thank's to all on this forum especially NZ Rossi.
                                      I'm thinking that the main reason people order a replacement power supply is that either they gave up trying to repair or didn't want to deal with attempting to repair it. The problem I see is that you received a defective board that you had to repair. Luckily, it was an easy repair, but what if it wasn't? I supect most people would be unhappy if this seller is dealing untested/broken power supplies. Nothing worse than taking something out of the box and having it not work.

                                      Comment


                                        Re: Dell 2407WFPb Monitor - Bad Cap

                                        Originally posted by jetadm123 View Post
                                        I'm thinking that the main reason people order a replacement power supply is that either they gave up trying to repair or didn't want to deal with attempting to repair it. The problem I see is that you received a defective board that you had to repair. Luckily, it was an easy repair, but what if it wasn't? I supect most people would be unhappy if this seller is dealing untested/broken power supplies. Nothing worse than taking something out of the box and having it not work.
                                        I actually bought this as a "Tested" board and can only presume that it was damaged in transit or by the "Agent" as they take it out of the packaging, photograph it to make sure it is exactly what you require, if he were to accidentally drop it then maybe the result of a broken Diode.
                                        I did replace all the damaged components that I could find, (I am a Truck Driver and not an Electronics Engineer!) on the original board at considerable expense when compared to the replacement board. Not to mention that some components are quite hard to source (2SK3548).

                                        Comment


                                          Re: Dell 2407WFPb Monitor - Bad Cap

                                          Originally posted by WillyBobz View Post
                                          Hi, Well.......... It finally came (4H.L2K02.A01), used PSU from China, upon close inspection I noticed that Diode 665 was shot (physically cracked and broken up), I replaced this with the component from my "Faulty Board", also changed C605 (which is the instigator of all the problems) with a QUALITY slightly larger diameter one, plugged in and *****Hey Presto!!!!***** Back up and running, this board was obtained from Chinese E-bay through and English speaking Agent (Taobao Focus), there are still some available, so don't give in! These monitors are FAR TOO GOOD to end up on the tip! My thank's to all on this forum especially NZ Rossi.
                                          i suspect D665 is also a dead diode on my board, it looks like a zener but it was mark with a D. Anyway can you please provide the numbers. Thanks
                                          D655 would be better
                                          Last edited by regino3rd@yahoo.com; 11-21-2011, 06:06 AM.

                                          Comment

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