Dell 2407WFPb Monitor - Bad Cap

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

nzrossi, do you mean when you replaced the MOSFET (2SK3502) with a new one & upon plugging in it got shorted straight away?.

[WillyBobz]

Re: Dell 2407WFPb Monitor - Bad Cap

Thank's for all the information NZROSSI, I have just looked on the website....wow it looks quite complicated! Can you give me any step by step instructions as to how to order, I will use the same agent that you used. Any help/advice GREATLY APPRECIATED!!!!
Regards
WillyBobz

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

nzrossi, do you mean when you replaced the MOSFET (2SK3502) with a new one & upon plugging in it got shorted straight away?.

Yes the new mosfet blew straight away. The replacement i used wasn't a k3502 but was the closest to its specs the local shop had, so that may have been the problem but I just got sick of trying at that point.

[nzrossi]

Re: Dell 2407WFPb Monitor - Bad Cap

Thank's for all the information NZROSSI, I have just looked on the website....wow it looks quite complicated! Can you give me any step by step instructions as to how to order, I will use the same agent that you used. Any help/advice GREATLY APPRECIATED!!!!
Regards
WillyBobz

1/ got to www.taobaofocus.com (It is not a well designed website...)

2/click on the 'taobao search' button, this will open another browser tab showing the taobao home page

3/ enter the board part no. 4H.L2K02.A01 in the search box at the top of the taobao home page and click the orange button next to it. This will bring up a list of these boards for sale on taobao at the moment, the price should be about 170RMB.

4/ click on one of these to go to the listing, make sure the pic looks the same as your board.

5/ Now go back to the Taobaofocus tab and click on 'Order' on the left of the screen under "bulletins"

6/ This leads to a prompt to login. follow the link to Register on the site first then login.

7/This should get you to the taobao focus "submit my chosen items" page. If not find the link for this on the left and click it.

8/ Now cut and paste the web address of the taobao page listing your board into the above page where it says "paste taobao item link" This then creates the order and list the first payment (about $36 US). You pay this and they then buy it, once they receive it they then ask fo the second payment to ship it to you. You get to choosed the shipping method in there somewhere.


Hope this helps

[WillyBobz]

Re: Dell 2407WFPb Monitor - Bad Cap

1/ got to www.taobaofocus.com (It is not a well designed website...)

2/click on the 'taobao search' button, this will open another browser tab showing the taobao home page

3/ enter the board part no. 4H.L2K02.A01 in the search box at the top of the taobao home page and click the orange button next to it. This will bring up a list of these boards for sale on taobao at the moment, the price should be about 170RMB.

4/ click on one of these to go to the listing, make sure the pic looks the same as your board.

5/ Now go back to the Taobaofocus tab and click on 'Order' on the left of the screen under "bulletins"

6/ This leads to a prompt to login. follow the link to Register on the site first then login.

7/This should get you to the taobao focus "submit my chosen items" page. If not find the link for this on the left and click it.

8/ Now cut and paste the web address of the taobao page listing your board into the above page where it says "paste taobao item link" This then creates the order and list the first payment (about $36 US). You pay this and they then buy it, once they receive it they then ask fo the second payment to ship it to you. You get to choosed the shipping method in there somewhere.


Hope this helps

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!

[knoxrebel]

Re: Dell 2407WFPb Monitor - Bad Cap

so were still not sure whats cauing this mosfet to fail.

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

so were still not sure whats cauing this mosfet to fail.

I am GUESSING the faulty Big filter cap is taking down a lot of components together with it as well.

Did anybody measure the resistance (with power off) between Pin 4 (gnd) and Pin 6 (vcc) of SMPS controller ncp1200?. Mine read 200 ohms (both ways). I think i am going to place order, replace it & let see how it goes (whether the mosfet will still blow immediately).

By the way, any expert opinion whether to change L6561D too?.

[WillyBobz]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi, I actually did replace L6561D (the original was still intact), replaced the Mosfet and everything else upstream (that I mentioned in my earlier post)of the cap C605, upon powering up it blew the top off L651 immediately! There is a post a little further up which refers to a power supply board in a 2405 which is very similar 48.L1E02.A02 and uses the same components, it looks like IC 601 (200A6) PWM Driver for standby is also involved, also ZD601 both of which are used in the 4H.L2K02.A01 board.

[WillyBobz]

Re: Dell 2407WFPb Monitor - Bad Cap

Hi, I actually did replace L6561D (the original was still intact), replaced the Mosfet and everything else upstream (that I mentioned in my earlier post)of the cap C605, upon powering up it blew the top off L651 immediately! There is a post a little further up which refers to a power supply board in a 2405 which is very similar 48.L1E02.A02 and uses the same components, it looks like IC 601 (200A6) PWM Driver for standby is also involved, also ZD601 both of which are used in the 4H.L2K02.A01 board.

Circuit diagram (Use google translator for rest of reports, it is in Russian!)
http://monitor.espec.ws/section33/post1216836.html

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

WillyBobz, many thanks for the information..

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

It seems like my faulty power board has more faulty components then those stated in Post #77. I tried to purchase the whole board from Taobao.com, as being shared above, but they are ALL out of stock. So back to ordering & replacing the faulty components one-by-one..

Now I need your help, guys!!..

In addition to post #77, i had another SMD resistor R623 faulty as well.. I think it is tied to one of the leg of Q601 (shorted as well). But the problem is i could not see clearly the marking on it. Kindly see the attachments.. From what i can tell it is 4(?)7.. But i can't be sure. SO, i will need some expert help what the resistance i should order to replace the burnt resistor.. I have not yet completely check the rest of the zeners/diodes.. Hopefully, there would not be more being 'shot'.

[PlainBill]

Re: Dell 2407WFPb Monitor - Bad Cap

4?7 is not a valid resistance. That would be over 400 megohms!!!

PlainBill

[newbie1]

Re: Dell 2407WFPb Monitor - Bad Cap

4?7 is not a valid resistance. That would be over 400 megohms!!!

PlainBill

Thanks PlainBill,..

That last digit on it looks to be number '7', to me.. And for the first digit i could see a part that looks like the top part of the number '4'.

I am guessing here but is it possible for it to be marked '4R7'? Means 4.7ohms? Is it a standard resistance?

[PlainBill]

Re: Dell 2407WFPb Monitor - Bad Cap

Thanks PlainBill,..

That last digit on it looks to be number '7', to me.. And for the first digit i could see a part that looks like the top part of the number '4'.

I am guessing here but is it possible for it to be marked '4R7'? Means 4.7ohms? Is it a standard resistance?

You, Sir are brilliant!!! Yes, that could be possible; indeed I am convinced you are correct.

PlainBill

[thewzard]

Re: Dell 2407WFPb Monitor - Bad Cap

Hey guys I'm back. Forgive me for the extended departure, work has kept me very busy as of late. Upon further inspection I cannot find any other blown/bad resistors/capicitors/etc. Now, remember I'm not an expert on electronics so I could be wrong but it looks like everything else is intact.

My new 450V capacitors are in and the specs are all good. I'll be putting one of these bad boys in sometime next week. I do have one minor concern though. When removing the silicon from underneath the 450V capacitor I scratched the surface of the board a tad. I'm going to post some pics and hopefully one of the experts will weigh in on whether I need to do anything special with that or not.

[PlainBill]

Re: Dell 2407WFPb Monitor - Bad Cap

Hey guys I'm back. Forgive me for the extended departure, work has kept me very busy as of late. Upon further inspection I cannot find any other blown/bad resistors/capicitors/etc. Now, remember I'm not an expert on electronics so I could be wrong but it looks like everything else is intact.

My new 450V capacitors are in and the specs are all good. I'll be putting one of these bad boys in sometime next week. I do have one minor concern though. When removing the silicon from underneath the 450V capacitor I scratched the surface of the board a tad. I'm going to post some pics and hopefully one of the experts will weigh in on whether I need to do anything special with that or not.

Good pictures; no problem with the scratches.

PlainBill

[Tyan]

Re: Dell 2407WFPb Monitor - Bad Cap

Hello together!

as a newcomer i first want to thank you all for the great help you gave me with this thread already!
On monday my own 2407WFPb quitted it´s service with a decent bang :-/ My first thought was "power supply" and i´m no person throwing stuff away without trying to fix it...

So i want to show you my attempt, too. Maybe it might help somehow.

The first step today was to open the case and check the internals. Tomorrow i´ll go to the local electronics store and buy the spare parts. My plan is to have the screen working again at the weekend.

I skip posting a pic of the whole board, as it´s already shown multiple times before in this thread.

The first thing i saw holding the power board in my hands was the well known resistor:


the second look went to the 450V cap:


and after some more "investigation" i found this:

on the diode (?) in the middle a little piece is missing in the upper left corner. So i think it would be best to swap those 3 too :-/

unfortunately my multimeter and my soldering equipment is in my workshop... so this was all i can do today.
I´m a mech engineer btw. and don´t have much plan of electronics... but i already did some soldering (wires and motherboards)!
And i´m german, so please be patient if my english might be funny

p.s.: could somebody tell me, on wich pcb i can find this little "printed" fuse? I can´t find it and all "Fs" seem okay.

[thewzard]

Re: Dell 2407WFPb Monitor - Bad Cap

It looks like all of these 2407s have the same problem. Maybe it was caused by a bad batch of the 450v capacitors?

[Tyan]

Re: Dell 2407WFPb Monitor - Bad Cap

meanwhile i´ve fetched my multimeter and tested some pieces.

The FETs are all ok but the Q651 is shortened (as expected).

Does anybody know something about these 3 Triacs in my 3rd pic? Their front isn´t labeled...

[Tyan]

Re: Dell 2407WFPb Monitor - Bad Cap

hm, no edit function here...

those 3 little friends next to the 5 condensators aren´t triacs, but double-diodes... and mine are workin... nvm -.-

just fetched my spare parts. Aren´t quite the same specs ("a 2SK 3402!? uuumph, nope, 2 weeks delivery, but i have a substitute!"), but should work. I hope. Pleeeeease!