Dell 2007FPB teardown

[Behemot]

If it's so cheap, sure. You can actually use the whole replacement board, if it's sold as working.

[Muggz]

Originally Posted by Behemot

If it's so cheap, sure. You can actually use the whole replacement board, if it's sold as working.

I may get that lucky, we will see. It was sold as being pulled from a monitor with a cracked screen.

[budm]

Check the resistance of the transformers of the new board first to see what you get.

[gastorro]

Originally Posted by ptg21

...
The key discovery though was the 2.7k ohm resistor under the "dielectric" glue on the usb board.
Confirmation from other users that it was the cause of their issues gave me hope -- a chance of needing just one single "repair" to get my monitor working correctly.
Sure enough, the suspected resistor was dead when I uncovered and tested it.
Now I just had to replace it.
...
Amazingly... it all worked! The monitor works perfectly now.
Again, a huge thanks to ac21, budm, and the entire badcaps board.
...

I had exactly the same problem ( random reset ) due to that 2k7 burnt resistor.

Thank you!

[gastorro]

my pictures of that resistor

[gastorro]

The above ^^ pics at their original resolution..

https://ibb.co/4pBxsgk 
https://ibb.co/NjZCQLg 
https://ibb.co/yfQYXV7

[Behemot]

Strange thing is, that resistor is hardly ever burned. In most cases, it looks fine, sometimes even measures fine, but still…

[Muggz]

New inverter board came, transformers all tested 1050-1060, threw it in, broke a connector, three solder jobs later.... it lives! Now I get to wrestle with Windows 7. THANK YOU for your help, Badcaps community and special thanks to Behemoth!

[Behemot]

Np. I'd recap it too, it's full of garbage, if that resistor does not kill it, the caps always do in the end.

[WB1]

I know a very old thread - but thanks to everyone on it who suggested the resistors under 'The Blob' on the USB board - mine was the 15k one that had gone open - replacing it with another SMD one taxed me a bit with a a rather large Weller iron - but - it did the job and came back to life !

I also re-caped the PSU while I was about it - I should hopefully get a few more years out my favourite 4x3 monitor now !!

Thanks again.

WALLACE.

[flemming_k]

Originally Posted by budm

After reading the http://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.

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

[budm]

Originally Posted by flemming_k

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?

[flemming_k]

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

[latenitetech]

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!

[A4000t]

Originally Posted by budm

After reading the http://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.

[migra100]

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

[Behemot]

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

[knightace]

Originally Posted by gastorro

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.

[knightace]

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

[migra100]

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