Dell 2007FPB teardown

[Behemot]

Re: Dell 2007FPB teardown

If you mean main transformer secondary, there's AC coming from it, you can measure DC after rectifier, preferably on a capacitor.

What would be a sine wave doing there?

[knightace]

Re: Dell 2007FPB teardown

It is hard to see from the photo what else has burned out, but if these resistors burned out, then most likely Q601, IC601 and something else burned out

You are Right that Burnt Resistor that I shared was linked with Q601 (Its a Transistor with Code 2SK3548, I'm not sure but im guessing it is used to create sine wave Electrical Signals), By the way the DC from the Transformer was above 1000V thats what my Multimeter was showing ( its max Limit is DC 1000V)

[knightace]

Re: Dell 2007FPB teardown

Today I took the Images from Closer look of the board. The Codes are pretty Clean. There was also some kind of Fume like colour on the Solder tips of the Components attached from the Top of the board and a high watt resistor Burnt/damaged. All the Images are shared. I would also be grateful if you people could find the root of this damaged, because what i did was only using multimeter and checking voltages across ground and points on the board (With board connected to AC Mains) and suddenly

The Images with name circuit-index will give you a proper view of the circuitry of the board ( I tried to take the negative so that all black becomes white . Thought the codes would be easier to read) .

[knightace]

Re: Dell 2007FPB teardown

So you write what serial numbers of resistors and zener diodes burned on the board, for example: R623, R613 .... and so on and I will write you the smd code of these resistors according to the scheme

I am so sorry for the image, I only shared it for Reference, Just to point out the Faulty resistors and zener diodes. I will upload full focused Image and images from different angles so that you get a clear image of the problem I have with the board. I will upload Complete set of Images of the board and the damaged part of the board with enough focus that you can clearly see the Resistor codes aswell as the Damaged Portion.

Thank you So much again for replying me.

[lotas]

Re: Dell 2007FPB teardown

It is hard to see from the photo what else has burned out, but if these resistors burned out, then most likely Q601, IC601 and something else burned out

[Behemot]

Re: Dell 2007FPB teardown

Me thinks the upper two which you selected are for the two components on the left side. For those two in the right side also the right two numbers apply. That would be JR2 and R613 I guess.

[lotas]

Re: Dell 2007FPB teardown

So you write what serial numbers of resistors and zener diodes burned on the board, for example: R623, R613 .... and so on and I will write you the smd code of these resistors according to the scheme

[knightace]

Re: Dell 2007FPB teardown

but its for Dell 2407 not 2007 plus I'm New in this Field . If you could really help with the area in the red Square. That area is burnt ( Resistors and A zener diode) if i could get the codes, i could replace them all. If you or anyone could arrange a Picture containing that area so that i could get smd resistor codes, I would be really really Grateful
The image of the burnt Part of PCB has been attached with this Post as well

[lotas]

Re: Dell 2007FPB teardown

Guys.. a little help would be appreciated. I have burnt power board of Dell 2007WFPB. This Board has burnt SMD resistors, the Board number is 4H.L2J02.A04. I have attached image of the board. if anyone could get me a clear picture of the board from bottom, kindly attach it with your reply, I am in a real need of the smd resistor codes on the bottom of the power board. The image for Reference has been attached with this post

Here is a diagram that should fit

[knightace]

Re: Dell 2007FPB teardown

Guys.. a little help would be appreciated. I have burnt power board of Dell 2007WFPB. This Board has burnt SMD resistors, the Board number is 4H.L2J02.A04. I have attached image of the board. if anyone could get me a clear picture of the board from bottom, kindly attach it with your reply, I am in a real need of the smd resistor codes on the bottom of the power board. The image for Reference has been attached with this post

[knightace]

Re: Dell 2007FPB teardown

I found the Problem, I was connecting the Connector the opposite way, that is the reason why the fuse blew. (Due to Direct Short Circuiting) but Now there is another problem, I got LCD Running Perfectly, but there is no Picture. I mean that The Backlight is OK and Working but there is no Picture, like No Input, or no Signal etc.

[migra100]

Re: Dell 2007FPB teardown

my lights from lcdpartsdirect arrived. i had some trouble soldering them so i only did one part before testing. it's hard to tell but the old ones and the new ones look about as bright. i really hope that isn't the case because the dell before taking it apart looked like the 92cd/m2 crt i've bought recently and that's not a good score for bulbs that claim to be brighter than original in an 300cd/m2 display

[knightace]

Re: Dell 2007FPB teardown

ok Guys today I replaced the Resistors and the Fuse. It worked but when I attached Panel, it again blew the fuse.Its not Powering on now. I don't know why is this happening. Any Suggestions would be greatly appreciated

[knightace]

Re: Dell 2007FPB teardown

my pictures of that resistor

Thank you So Much Gastorro. I was searching for this. I actually damaged the 272 Resistor alongside with its fellow resistors, I was hoping to resolder them all but since I'm new in this field and was just doing it for repair, I damaged their Codes while removing that white glue like stuff. Now I tried to check their Resistance and found that the Resistor with code 753 is not working.Resistor with code 473 is showing only 762 ohms resistance. And I accidently damaged the board from where 272 SMD Resistor was . Luckily i tried to perform the continuity test and luckily it beeped so no short circuits and Flex is ok. Also I tried Continuity test on 3A Fuse, It also seems to be blown out. With your Attacked Clear picture, I now have the Resistor codes. Will buy new resistors and then replace them . Thanks Again, I was really searching for an image for the resistor codes. everywhere they are covered with white glue.

[Behemot]

Re: Dell 2007FPB teardown

Many 20" displays do have such thick diff plastic and 6 tubes.

[migra100]

Re: Dell 2007FPB teardown

i think this is an appropriate thread for this because i teared down this monitor even more. i bought it used and after over 50k hours it got rather dark. it doesn't look that bad compared to my 2009 lg tv with less hours but using it during the day can get irritating and it's way darker than my new cheapo 250cd/m2 monitor.
i've seen people replacing the ccfl lamps with leds but connecting that to the board can get complicated and the colors looked off in the video so i would rather not do that.
i found a website selling those lamps but i'm not sure if they aren't scamming people.
https://lcdpartsdirect.com/product/4...creen-monitor/
are 4 lights instead of original 6 enough ?
are they really going to ship them to europe for 4 dollars ?
also, i have another question. should i be able to see this display without backlight while lighting it from the top ? i took both modules off and i can't see anything but everything else works as normal.
edit
After further testing the display is still working, i had to lit it from the back which required talking off the rim again. Now that i know i didn't break it i can buy the backlight. I'm still not sure about that store, i would be grateful for any help with that.
btw. i've never seen diffusion layer(?) that thick. i can take more photos when i put it back together

[A4000t]

Re: Dell 2007FPB teardown

After reading the https://www.badcaps.net/forum/showthread.php?t=10658
on Dell 2007. I found 2 of them today and took them apart to see how it is put together.
What I found are:
1) It only has one always on DC power supply output of 19V.

2) The 19V is fed to the Backlights inverter board.

3) The 19v is also fed (J4) the USB Hub/3 Buck converter regulators (3.3V (Q6) for the Logic board where the VGA/DVI, control panel are, 5V (Q14) (this 5V is also fed into 3.3V linear regulator for the USB interface IC) for the 4-port USB hub (these 4 USB ports are protected by 4 fuses), 12V (Q9) for the powered speaker bar DC output jack. This 19V is fed through 3A fuse. MOSFETs Q6, 9, and 14 are 2SJ598, P-Channel.

4) If the USB/Buck converter is not connected, the monitor will not work.

5) The 3.3V output from the Buck converter is fed back into the logic board which feeds U13 (1.8V Linear regulator) and U5 (2.5V Linear regulator) to run the LOGIC IC's on the logic board.

6) One bad design in the Buck regulator is that they parallel 2 Schottky Diodes together (http://electronics.stackexchange.com...des-a-bad-idea) to try to get more current handling, but if you do not precisely match the Vf of the Diodes, the one with lower Vf will be on, the one with higher Vf may not be on at all. They should have use single 2 or 3A rating Diode instead of 1A rating, Diodes are rated at 1A 40V. This may explain why this model has the same failure mode due to shorted out diodes.

I just fixed one of these today,its a A.01 rev and it had a bad 15K resistor under the blob of silastic. It was open.

[latenitetech]

Re: Dell 2007FPB teardown

Another Dell 2007FPB lives again ...
I just wanted to thank the folks on this forum and this thread in particular. My "old friend" monitor died recently. The symptoms were the screen would come on for a second or so, then the backlight would go out, but the LED indicators on the front stayed lit. Per this thread, that led me to checking the inverter board, and the resistance of the transformer windings. I found one transformer with one winding that measured open vs. the other two (nice that there are 3 identical transformers on the PCB to compare). That gave me confidence in buying a replacement inverter board on eBay for $14 shipped. When it arrived, I popped the replacement board in and wala working monitor again. It's been working now over a week, so I'm pretty confident it was a good fix. Without this forum, I would have been hard pressed to diagnose this on my own. Thanks again!

[flemming_k]

Re: Dell 2007FPB teardown

Thanks Budm
Yes I also read about the 2k72 resistor. I checked it with the multimeter. It looks good.
The Schottky diodes also look good.
Since the screen goes black, and the loudspeaker looses 12V at the same time, the cause could be in the PSU board,
That board looks fine visually. Should I just try and replace all the caps?
You have a diagram of the PSU also?
Please advise
Flemming_k

[budm]

Re: Dell 2007FPB teardown

Hi Budm
My monitor goes black after a couple of hours. I guess the two parallel Schottky diodes could be the cause.
Could you show me in a picture where they are located?

Thanks
Flemmig_k

Those parallel connected diodes are on the USB board assembly.
https://www.badcaps.net/forum/attach...6&d=1336880613

Did you read the threads about the bad resistor under the white glue blob that you need to check?