Dell 2407WFPb Monitor - Bad Cap

[senquack]

Re: Dell 2407WFPb Monitor - Bad Cap

If the monitor doesn't work after replacing these caps, check the surface-mount fuse on the smallest PCB, the one containing two DRAM chips and a large square IC. It is blown on the bad monitor I have here. It is labelled F1 I think or something Fxxx.

You can buy very small micro pigtail fuses to replace it with. Not sure what amperage rating it is so I cannot be of help there. Someone here can probably help if it turns out to be bad. Just cut the leads of the new fuse a bit short, bend with pliers into a tight "U" so they fit snugly around the old fuse, and add new solder to each side, leaving the bad fuse in place. Other fuses might be bad, too.

Thanks for the thread, BTW, I am going to use this info to hopefully repair this one.

[Toasty]

Re: Dell 2407WFPb Monitor - Bad Cap

<snip> It is blown on the bad monitor I have here. It is labelled F1 I think or something Fxxx. <snip>

That's the video processing board. If it's blown there, then it's likely the regulator chip is toast. Right above the HDMI connector, IIRC.

That could have happened because of a serious malfunction of some other component on the video board -or- the power supply went haywire and over-volted or bad caps in the PSU caused a very high ripple to be passed to it. Either way, you'll have to figure out the problem before just replacing the fuse. Those fuses get pricey fast.

Toast

EDIT: post a photo of the fuse and the markings please

.

[discopig]

Re: Dell 2407WFPb Monitor - Bad Cap

I would also like to thank you all for this thread... the information here has been invaluable to me. and Out of interest my 450v cap looks identical to thewzrds initial photos ( with goo coming out of it ). So I am ordering the suggested replacement and Toastys recommendations on howto fix...

Once again. many thanks.

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Me too!

Exact same problem. The photo on post #10 is identical to how mine looked. So much for it being unusual for large caps like this to fail.

This is my first time to so I have found this thread invaluable, thank you all for your contributions, especially Toasty for his patience...

Now the big Question...?

Did It work? Has thewizard got his monitor running again? How about discopig?

Will be doing this myself shortly and it would give me big warm fuzzies to here that it has been successful for someone else.

Discopig are you going to replace all the caps or just the big bad one?

[discopig]

Re: Dell 2407WFPb Monitor - Bad Cap

Me too!

Did It work? Has thewizard got his monitor running again? How about discopig?
...
Discopig are you going to replace all the caps or just the big bad one?

Hi,
I replaced ALL the of caps on my powerboard, and I also replaced the 4a fuse and a burnt out resistor.... I did purchase all the parts from Farnells ( UK version of Element 14 ).. but out of interest there is a guy on Ebay which sells complete Cap replacement kits for most monitor models. Well excluding the 450v cap...

Anyways, from there, after testing each cap individually after replacement, the fuse and the resistor, I powered on, and Bang... the fuse went ( wearing safety goggle or standing a safe distance is not a bad idea on first test if you are a newbie like me ).

On close inspection of the power board... the board is looking scorched ( from wear not my testing ), So to be frank I am at a loss as to how to possibly fix this.. I have inspected all the parts on the board, and cannot see any damage. So I am suspecting the trouble is elsewhere or just plainly beyond my limited knowledge on the subject.

Any suggestions?

All the best Disco

[jetadm123]

Re: Dell 2407WFPb Monitor - Bad Cap

1) Please post some good focusesd photos of the top and bottom of YOUR power board. Use the "manage attachments" button to post your photos.

2) As for the blown fuse, did you verify that you installed all the caps corrrectly? Check that the polarity is correct. Make sure there are no solder bridges .

3) Indicate on your photo which resistor you replaced. This could be a clue.

[psykosonik]

Re: Dell 2407WFPb Monitor - Bad Cap

Howdy All,

Just signed up to the website as this is the only active forum discussing the repair of a Dell 2407 monitor.

I have recently obtained three of these. Of the three only two are working.

I hope to gain some assistance and also contribute on repairing the monitor!

So far the following items i have identified are blown on the power supply board.

1x 400v Cap
1x .22 ohm resistor
1x 250v 4A fuse
1x unknown IC

Cheers,
Pete

[psykosonik]

Re: Dell 2407WFPb Monitor - Bad Cap

Flip the power supply board around and check to see if the top of a ic's have blown off.

[psykosonik]

Re: Dell 2407WFPb Monitor - Bad Cap

Shook the monitor and found pieces to make up the missing ic dont have the product number but did manage to find a logo which is ST (STMicroelectronics) and EZ624...

Trying to locate this IC

[PlainBill]

Re: Dell 2407WFPb Monitor - Bad Cap

One of the frustrating parts of trying to help people repair their monitors is the difficulty of getting information. Some monitors have service manuals available; others don't. Service manuals for Dell products are hard to find.

With the information you give, I can deduce a few things. The monitor was made by Benq for Dell. It's a 24" screen, so the power supply probably has main and standby sections, and a PFC front end. Searching on the fragment of a part number you gave generates only a few hits. Interestingly, one was on the ST Microelectronics web site.

The single most important piece of information we can get is a description of the problem; I've got a pretty good idea of that, no further details are required. The second most useful piece of information is pictures of the monitor - in this case, of the power supply. Attach them using 'Manage Attachments' - below the text entry area.

Now, if you would be so kind as to provide top and bottom pictures of the power supply, just maybe someone will recognize the related model of Benq, or have seen the same power supply in another brand of monitor - HP also buys their monitors from Benq.

PlainBill

[Toasty]

Re: Dell 2407WFPb Monitor - Bad Cap

Why not open one of the other monitors and get the part number required?????

[CaScAdE]

Re: Dell 2407WFPb Monitor - Bad Cap

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

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Woah, you have lost me there cascade, that board doen't look the same as mine or the others posted here, you sure its a Dell 2407WFPb?

I am still waiting fo my replacement 450v 120uf cap to arrive but have noticed I too have a blown .22 ohm resistor as shown in this pic

https://www.badcaps.net/forum/attach...6&d=1305906535

the same resistor as psykosonik and discopig I guess (and therefore probably 'the wizard', you should check this resistor...)

Having a bit of trouble tracking down a resistor like this one, the only .22 ohm or '0R22' resistors available locally are big square blocky wire wound resistors. Is this one as pictured likely to be wirewound or carbon ? Does it matter? It is 11mm long and 4mm dia. Also what wattage do I require for the replacement?
I found a datasheet here:
https://cdn.badcaps-static.com/pdfs/...e724c6917a.pdf
and going by the dimensions on it the size that matches mine is 1W.

Still waiting to see that "my monitor is alive again" post. Suspect I am wasting my time and that there may be numerous ICs and other components on my (our) board(s) damaged.

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Well it didn't work for me either

Replaced the blown 450v cap, the .22ohm resistor and the 4a fuse and applied power, the monitor didn't come to life and the new fuse on the power board blew.

(I decided to only replace the one obviously blown capacitor for 2 reasons
1. Occams razor/if it aint broke don't fix it; 2. Others here have replaced all the caps and still had no success so it seemed like a waste of money/time)

Can anyone please advise what else on the board i should replace or test (inc how to test it, I'm a newbie).

The board model number is 4H.L2K02.A01 or altn number 5E.L2K02.001 made by BENQ. I cannot see any other damaged looking components or scorching on the board, including the ic on the underside of the board mentioned elsewhere. I have attached photos of both sides of the board. I read somewhere that when these large caps blow they often take out other components with them...

[Toasty]

Re: Dell 2407WFPb Monitor - Bad Cap

Bad switcher MOSFET is where my money goes. From experience, when the mains caps go, they do take out the switchers.

The blown fuse and resistor are telltales.

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Thanks very much Toasty, that is just the kind of hint I needed to get me moving in the right direction. I take it the switcher MOSFET will be the one attached to (and obscured by) the heat sink next to the fuse on my pic.

This seems especially logical because it is between the resistor that blew and the fuse that blew. I have tested it in situ and it has continuity between all combinations of D, G and S, which i take it indicates it is blown. I will pull it out and test it in isolation next.

[endor]

Re: Dell 2407WFPb Monitor - Bad Cap

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

[WillyBobz]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi All,
I have the same problem with my Dell 2407 WFP power supply board, I have spent hours and replaced, C605,F601,R670,R669,IC651,Q651 and it still went POP! I would like to replace the board completely,but I am having great difficulty finding one. Does anyone know of a suplier in the U.S as they seem far more common there than in the U.K. It seems such a shame that this Monitor is destined for the tip just because the board is not available.

[everlong]

Re: Dell 2407WFPb Monitor - Bad Cap

Same problem here, a completely dead 2407wfpb.

I tried take some pictures of my powersupply, and I got thinking that there might be better to buy a new Dell, maby u2711 than try to fix this..

I tried search for complete powersupplyes but all I could find was this repair kit:
http://www.ebay.com/itm/Repair-Kit-D...ht_4154wt_1164

But I don't know, my soldering skills isn't that good!

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi Guys

I was not able to repair my power board. After replacing the Big Bad Cap, the burnt resistor, the fuse (many times) and the switching MOSFET (only to have it blow again straight away) I gave up.

I sourced a replacement board through taobao, the chinese ebay, there are lots listed there under the board part number. I went through an english agent, taobaofocus.com. You pay them once and they bid and buy the item for you, then once they have received it in China you pay them a second payment for them to ship it internationally to you. Cost me about 50usd total including shipping to New Zealand.
Monitor now up and good as new. I replaced the big cap with the new one I had bought for the repair which hopefully will be less likely to blow.

Best of luck.