Dell 2407WFPb Monitor - Bad Cap

[sabretooth]

So, pin 6 has continuity with C613
Pin 7 - not connected. that was the one I was worried about. The surface scratching I did probably turned up nothing because there actually is nothing there.
Pin 8 - still has continuity with R603

I'll see if I can find some wire to solder through that hole.

[WillyBobz]

Originally Posted by sabretooth

So, pin 6 has continuity with C613
Pin 7 - not connected. that was the one I was worried about. The surface scratching I did probably turned up nothing because there actually is nothing there.
Pin 8 - still has continuity with R603

I'll see if I can find some wire to solder through that hole.

Hi Sabretooth

Yes that is correct, but ALSO pin 6 goes through board to to the Positive side of Electrolytic Cap C611 (50V 47uF).

Hope all goes well!

[sabretooth]

OK, all looked to be in order. The various points had continuity, all parts back on/replaced etc.

Powered it on, and the fuse popped right away.

I'm guessing that the best route from here is just to do the external power supply mod described a few pages back. I'm out of ideas and knowledge on how to fix this.

[sabretooth]

Also, for interest's sake I replaced R615 and each time I plug in AC power both the fuse and R615 blow.

[selldoor]

Originally Posted by sabretooth

Also, for interest's sake I replaced R615 and each time I plug in AC power both the fuse and R615 blow.

Well you have given it several best shots

Can you just confirm which fuse is blowing.

[selldoor]

Probably too late but if R615 keeps blowing is Q601 Shorted as it is connected direct to it - This was mentioned briefly as having shorted in an earlier post, but blew the resistor on another leg.

[sabretooth]

Thanks for the tip. I've removed Q601 for testing and will see if I can source another one. I've got another 8 0.22ohm resistors left, so it certainly can't hurt to try again.

But, using the advice from Adrian on page 4, I've done the workaround. And, well, with the help of an AC adaptor from an old HP laptop it works! Seeing the front panel circuit board light up was a very happy moment.

After I find another Q601, I'll try fitting it and report back with my findings.

Thanks for the tips and your time - it's rare to see a forum this helpful towards complete strangers. I can highly recommend AdrianM's method as an easy way out if your soldering/diagnostic skills are limited.

[benno420]

Thank you AdrianM. Used your method and it worked!

[chrisw76]

Another big thanks to AdrianM as the external power option does it again!

About a week ago I was working in front of my DELL 2407WFPb and heard the dreaded pop of the 120uF 450V capacitor blowing. I also smelt the dreaded dead electronics smoke at the top.

Initially, I thought I would try a repair, but after examining the board and reading the threads here it became obvious that repair was going to be a big job. From just a cursory examination with a multimeter it was apparent that in addition to the capacitor, the MOSFET was gone, along with the 0.22 Ohm resistor (cover blown off) and at least two of the surface mount diodes on the bottom of the board were gone. Probably some of the other components were gone too.

After trying the Taoboa route and finding out over the course of the week that despite 1/2 dozen auctions, no seller has the power board available anymore, I decided to try the AdrianM's bypass method.

After completing the bypass operation on the sound bar power socket, desoldering the mains plug (just to prevent future mishaps!), and removing the offending capacitor, I picked up a generic Chinese made ThinkPad X60 charger from TradeMe rated at DC 20V 4.5A 90W (here if anyone interested: http://www.trademe.co.nz/Browse/List...x?id=479307991). Note that with this seller I had to find a power cable separately for another NZD 8.

There are cheaper ones available, but impatience got the better of me and this one was available today. From the local JayCar I picked up a DC 2.1mm plug and snipped off the IBM style plug. Putting the plug on was straight forward as there were only two wires (red positive and white negative). When complete, powered up and unloaded voltage measured 20.47V on the plug.

It was a bit of a heart in mouth moment when I plugged it in, but when the test pattern showed up it was great!

As I picked up the DELL second hand about a year ago the power supply may have already been on its way out, as while it could be my imagination the brightness definitely seems to be improved with this new power source.

Overall cost to implement the external power solution was about NZ 46 + a bit of solder, wire and time. Definitely well worth it so far!

Cheers, Chris W.

[funkster]

I have a dell 2407wfpb, been a few years since I bought it new. It's been making some hissing sounds sometimes and there is no warranty anymore. I've been reading through all these threads & I'm just wondering if there is a way to prevent the power supply from faulting and going pop.

I opened it up just to see if the big 450V 120uf capacitor had started any corrosion on the positive pin but it looks fine. If I measure votage across the positive and negative pins would that be a means of testing the capacitor? or do I need some special tester.

[FIXITNOW]

stop using it and the C605 120u/450V change it quick
if it goes it will blow up the psu these are a known week point

[personmans]

I have been reading this thread in hopes that I can fix my 2407WFPb monitor.

I have the same problem as the OP and a few others. No power when the button is pressed on the monitor.

The top of the board shows damage to the large cap:
C605 - (To be replaced with EET-UQ2W121BA):


The bottom side of my board shows damage to:
IC651 - (To be replaced with L6561D)
R674 - ???
Q654 - (To be replaced with MMBT3906)



Additionally, I plan to test/replace the following items that have been reported to be related to this issue:
Q651 - STP10NK60ZFP MOSFET (Top)
R669 - 1k 0805 resistor (Bottom)
F601 - T4A HBC fuse (Top)

Can someone help identify R674? Is there anything else to replace that I'm missing?

[personmans]

Here is a better picture of the back where there is obvious damage.

[elvena]

How did it go?

I'm having the same issues other people experienced, in my case, I was using the monitor and I just heard a POP, monitor dead, UPS fuse dead.

For the moment the casualties on my monitor are:

1) F601 - T4AH 250v
2) C605 - elite 120uf 450v 105c
3) Q651 - replacing with STP10NK60ZFP
Original sheet: http://www.alldatasheet.com/datashee...3502-01MR.html no?
4) R670 - 0.22 ohm -- visible burnt

The rest in the area seems ok, not sure about the IC651/IC601 - checking Ω shows different values and I didn't find a replacement "fast"

I'll replace those four and I'll post some update/pics ! ..

Invaluable thread information by the way, thanks!

[elvena]

Well, after replacing the mentioned parts, IC651 blew off and R669 too.

The new mosfet also died (Q651) - Q601 still good.

Hard to find the IC651 (L6561D) over here so.... I'll post back when I get my hands at one of them.

[ondrugs]

AdrainM, thank you!

I tried replacing components, but that didn't work (£25 later). That's because I have not clue what I'm doing. My electronic capability stops at being able to use a switch (the on/off kind, not the computer kind).
So armed with a better soldering iron (30W is not enough to melt the solder on these boards) and a multimeter (which I need to learn how to use better), I got my screen up and running.
FYI, I used a Toshiba PA3467e-1AC3, rated 19V, 3.42A, 65W. the plug fits fine. it does feel a little warm though, so I'm going to see if I can get a 20V 100W supply from somewhere later.
So for any non-electronic types like myself, skip straight to page 8 of the thread!

thanks again!
Andre

[elvena]

R674 is not the clearest to read, but mine seems to be 8251 and the multimeter confirms with a ~8.1k

Originally Posted by personmans

I have been reading this thread in hopes that I can fix my 2407WFPb monitor.

I have the same problem as the OP and a few others. No power when the button is pressed on the monitor.

The top of the board shows damage to the large cap:
C605 - (To be replaced with EET-UQ2W121BA):


The bottom side of my board shows damage to:
IC651 - (To be replaced with L6561D)
R674 - ???
Q654 - (To be replaced with MMBT3906)



Additionally, I plan to test/replace the following items that have been reported to be related to this issue:
Q651 - STP10NK60ZFP MOSFET (Top)
R669 - 1k 0805 resistor (Bottom)
F601 - T4A HBC fuse (Top)

Can someone help identify R674? Is there anything else to replace that I'm missing?

[elvena]

FIXED!

After changing F601, C605, Q651 and R670 on powering on got Q651 + R670 + IC651 (!! ) + SMD resistor R669 shorted/blown, the fuse survived to my surprise. (Taking photos of the entire board saved me, that way I figured out the R669 value)

Then, I removed again the broken parts, changed Q654 as I detected that it was bad (Suggested on this thread), and added a new R670 + Q651 + R669 , result: Q651 + R670 + F601 dead instantly. Good thing I didn't added a fresh IC651 !

3th try: I changed Q651 (3th time), R670 (3th time), IC651, IC601

Re-checked the Q654 and -several- diodes / resistors / transistors before powering on .. all were good.

On powering on, nothing happened, which was a good thing since I was just connecting to the AC.

Took my monitor and connected the power supply to it, on powering on the DELL logo was waiting for us ( My girlfriend helped a lot on the process )

Some information on this thread is invaluable, was a fun process finding myself reading it over and over and always contained something new that I didn't fully get the first time :P

So!, basically the C605 went down making IC601 to malfunction, C605(Or maybe was IC601 after being hit) also took the mosfet (Q651) and with him the Q654 + R670 went down.
On 2nd try, was all the same except they were working again AND IC601 was still bad, that mistake took IC651 down this time alongside with R669, Q651 clearly stating that something was really bad.
3th try = success!

TL;DR:

Things I've changed / model:

Q651: 2SK2843
Q654: MM3906
IC651: L6561D
IC601: Was NCP1200AD60 (200A6) changed for NCP1200D60 (200D6) - notice the lack of the "A", this "A" means that is a newer version of the chip, both are pin to pin compatible, and seems this circuit allows both to run (Im still not sure if these chips are fully swappable 100% of the designs)
F601: Same kind of fuse: T4AH
C605: 450v 150uF snap-in capacitor -- waiting for a replacement that will FIT into it when closed :@

I suspect that the OLD NCP1200 had a problem between the pins 5 and 6.

The "PWM" part (Except for the chip itself *sigh*) of the power supply never had a problem in my case (IE, Q601 never shorted)

Thanks and good luck!

[jetadm123]

Good work! First really successful repair of this model monitor that I have seen. Also, to save members from looking, can you please supply the values of the resistors you replaced? Thanks!

[Duncanbest]

Originally Posted by elvena

FIXED!

After changing F601, C605, Q651 and R670 on powering on got Q651 + R670 + IC651 (!! ) + SMD resistor R669 shorted/blown, the fuse survived to my surprise. (Taking photos of the entire board saved me, that way I figured out the R669 value)

Then, I removed again the broken parts, changed Q654 as I detected that it was bad (Suggested on this thread), and added a new R670 + Q651 + R669 , result: Q651 + R670 + F601 dead instantly. Good thing I didn't added a fresh IC651 !

3th try: I changed Q651 (3th time), R670 (3th time), IC651, IC601

Re-checked the Q654 and -several- diodes / resistors / transistors before powering on .. all were good.

On powering on, nothing happened, which was a good thing since I was just connecting to the AC.

Took my monitor and connected the power supply to it, on powering on the DELL logo was waiting for us ( My girlfriend helped a lot on the process )

Some information on this thread is invaluable, was a fun process finding myself reading it over and over and always contained something new that I didn't fully get the first time :P

So!, basically the C605 went down making IC601 to malfunction, C605(Or maybe was IC601 after being hit) also took the mosfet (Q651) and with him the Q654 + R670 went down.
On 2nd try, was all the same except they were working again AND IC601 was still bad, that mistake took IC651 down this time alongside with R669, Q651 clearly stating that something was really bad.
3th try = success!

TL;DR:

Things I've changed / model:

Q651: 2SK2843
Q654: MM3906
IC651: L6561D
IC601: Was NCP1200AD60 (200A6) changed for NCP1200D60 (200D6) - notice the lack of the "A", this "A" means that is a newer version of the chip, both are pin to pin compatible, and seems this circuit allows both to run (Im still not sure if these chips are fully swappable 100% of the designs)
F601: Same kind of fuse: T4AH
C605: 450v 150uF snap-in capacitor -- waiting for a replacement that will FIT into it when closed :@

I suspect that the OLD NCP1200 had a problem between the pins 5 and 6.

The "PWM" part (Except for the chip itself *sigh*) of the power supply never had a problem in my case (IE, Q601 never shorted)

Thanks and good luck!

The biggest difference between NCP1200 & NCP1200A is driving current at pin5 DRV .

NCP1200 =110mA NCP1200A =250mA