Dell 2007WFP Won't Power On

[craftsman1234]

Re: Dell 2007WFP Won't Power On

@MEB, I ran out of idea for you to check (I love that show).
@craftman, it probably has shorted MOSFET's so it blew the fuse the first time.

Thanks you are the expert. It also blew the one next to the capacitor in the photo as well. This cap was the one that showed the bulge. The new fuse held this time very strange. Do you think that it is worth repairing? I'm worried about getting a new inverter board to have the same thing happen to it.

Not sure if I can do that type of solder work but if the parts are cheap and easy to get. Once more unto the breach...

[budm]

Re: Dell 2007WFP Won't Power On

I myself do not believe this is the good chassis due to fail components in the sub-power supply board (where the 5V, 3.3V, and 12v are generated). The Inverter board just runs off the main power supply board (it puts out the 19VDC), so if you get the new inverter board and other board is good then you may be OK. You can check the rest of the power supply section without the inverter board connected.
MEB has lots of problem with his sub-power supply board but he may have good inverter board, you two can do some trading to make one working monitor out of the two monitors.

[craftsman1234]

Re: Dell 2007WFP Won't Power On

I myself do not believe this is the good chassis due to fail components in the sub-power supply board (where the 5V, 3.3V, and 12v are generated). The Inverter board just runs off the main power supply board (it puts out the 19VDC), so if you get the new inverter board and other board is good then you may be OK. You can check the rest of the power supply section without the inverter board connected.
MEB has lots of problem with his sub-power supply board but he may have good inverter board, you two can do some trading to make one working monitor out of the two monitors.

Thanks. Yes seems to be lots of problems with this monitor. I use them because of the s-video can be used with my old Commodore's. A bit rare nowadays.

[budm]

Re: Dell 2007WFP Won't Power On

Where is Northglenn?

[craftsman1234]

Re: Dell 2007WFP Won't Power On

Where is Northglenn?

It's near Denver, Colorado USA

[MEB]

Re: Dell 2007WFP Won't Power On

@MEB, I ran out of idea for you to check (I love that show).
@craftman, it probably has shorted MOSFET's so it blew the fuse the first time.

Thanks for that budm. Lord knows I have no idea, but I can't give up yet. I have some basic questions if you want to take a crack at them.

Please correct me if I am wrong and point me in some direction. I need to do some crawling before I can walk.

On my application, is my power board's main function to take 120V AC and supply 19V DC to the other boards (USB/DC, logic and inverter)?

And is one of the jobs of the USB/DC board to use the 4 "buck regulators" to make 3.3V, 5V, 12V and some other voltage available for use on that and the other boards?

I feel the power button goes to the logic board to get things started, but can you explain a little what happens?

Also, I have made a little sketch to try to better understand the "buck regulators". I borrowed your previous drawing as a start and would appreciate corrections and comments. If it is not valid, feel free to tell all not to use it. I am not claiming it to be correct.

[budm]

Re: Dell 2007WFP Won't Power On

"On my application, is my power board's main function to take 120V AC and supply 19V DC to the other boards (USB/DC, logic and inverter)" Yes, that is the main power supply that supplies the 19v to run the inverter board and for the USB/DC board which steps down to 3.3V, 5V, and 12V.
The 3.3V is used for running the micro controller on the Logic board which accepts the signal from the power switch which then sends the signal to turn on the 12V and the 5V.
The Vin should go into the Source pin of the MOSFET, the MOSFET is used as a high speed switch.

https://cdn.badcaps-static.com/pdfs/...25211cb74c.pdf

https://cdn.badcaps-static.com/pdfs/...2d4b38ca9c.pdf

[MEB]

Re: Dell 2007WFP Won't Power On

Thanks. Read all the pdf you suggested and it still hasn't clicked yet. Not sure if I am getting off the subject in this thread, but I've been yelled at before. I have been trying to understand this and the following are my reasonings and not statements. Hope you can fill in the missing pieces.

This USB/DC board is supplied 19V DC from my power board upon connection to AC.
This supplies directly to the source of 4 Mosfets via connector on the logic board, these 4 Mosfets being the electronic switches for the 4 buck regulator circuits to step down to 3.3V, 5V, 12V and ?V for other uses.

So, if the source is the same, the drains are the regulated output and the buck regulator circuits are composed of the same value components, then the gate signal must contain information that dictates the output of the Mosfets. That information to the gate must be in the form of DC which cycles on/off in a pulse?

So tracing back from the gates, it seems they are supplied from (2) TL1451A which each feeds a pair of the Mosfets. These 2 chips must evidently supply a pulse of a certain width and duration to switch the Mosfet on and off.

But what tells these 2 chips what to do and how do they do it. More basically, how do I get 3.3V versus 5V versus 12V when all of these circuits use the same components? It has to be from information placed on the gates, but I can't grasp how this whole thing fits together yet. Please help me get this straight so I can move on.

[insanezz]

Re: Dell 2007WFP Won't Power On

@MEB, I know you've probably read my reply 2-3 pages before, but I see fit to give you an advice here, even as non expert to non expert.
So, I don't know what is the situation with the inverter board you have and why it is blowing its fuse, but if you have worked that out, I can advise you to check the two voltage regulators on the logic board (top right corner). If they are OK and you don't see any shortage to ground (except their own one) then your logic is most likely alive.
I've got my hands on 4 dead displays of these at work and 3 of them had no problem with these regulators on the logic and their logics are actually alive. The one with shorted regulators to ground is not OK, and even without them the PCB is shorted to ground there - most likely the main chip is shorted.
So if yours are OK and we assume the whole logic is OK, if I were you, I would test if the monitor is able to work with 3.3V and 12V plugged to the logic, where the "USB" board should be. You can check where they need to be from the graph I've posted previously, or measure them from your working monitor. I've use a spare PC PSU to have 3.3V and 12V.
As agreed before the 3.3V are used to power up the logic itself. BUT, the 12V are not just for that stupid speakers, anyway. They are used to power up the LCD panel, so you HAVE to have them plugged to the logic board. This is the reason to see only a blank screen with working logic and working backlight. You don't need the 5V, so don't bother.
It everything is OK and the test went well for time you see fit, you can use the same trick I did.
http://www.ebay.com/itm/140716238408...84.m1439.l2649 (LM2596 DC-DC adjustable power step-down module)
Only two of these ten adjustable DC-DC converter boards can replace the 3.3V and 12V supply if you feed them from the 19V of the power board. They are small enough to fit in the place of the "USB" board with the cabling you should do.
Of course this whole "fix" can take place only if you see fit to loose the USB hub and the external power for speakers.
I know the whole thing doesn't sound quite scientific and more like made in some garage, but this is what helped me fix 3 of 4 of the dead displays, so I'm sharing it with you.

[MEB]

Re: Dell 2007WFP Won't Power On

Thanks isanezz, I had pretty much given up on the problem at hand because I wasn't getting any replies from the guys out there and I am at a loss on how to proceed. I had read your post numerous times and will take your advice on buying those boards from ebay. I had previously borrowed a DC power supply, but I like your idea of being able to supply multiple voltages to different circuits at the same time. The price is right and I am sure that they will be handy as I learn more later on.

I will check the areas you suggested, especially the voltage regulators on the logic board. I assume you are referring to U5 and U13. I will get set up again and let you know what I find out.

While waiting for direction, I have built the "blue" ESR meter and downloaded LTSpice. budm turned me on to buck regulator circuits and I had a hard time grasping how they actually functioned, so I ran across the free download and was able to satisfy in my mind how they work by being able to change component values and the gate pulse and actually seeing the effect of these changes on the various waveforms.

Now your reply has given me a reason to get back on the horse, so to speak and am looking forward to it. Thanks for your thoughts. If you celebrate Christmas, have a good one.

[MEB]

Re: Dell 2007WFP Won't Power On

sorry, insanezz

[freeone]

Re: Dell 2007WFP Won't Power On

Hello!

Sorry for pulling up this old thread, but my monitor is just died on me. Dell 2007 WFP, worked fine, i leaved it for 2 minutes, and when i returned, it smelled bad, and no power, no leds, no picture. After disassembly, i found 2 bad caps, i replaced the main puffer(originally 180uF 450V, replacement: 150uF 400V), and the explicitly blown 220uF 25V one, and it's 2 other friends, with the same type of caps. The other power supply caps looks ok, and they read to be ok with an ESR meter. Still no power. Can anyone help me, where to look for problems? The blown caps are marked with red circles.

[freeone]

Re: Dell 2007WFP Won't Power On

I just found that a diode is reading very low in diode mode(0,057 in both directions), is it faulty? What type of diode it can be? Thanks!

[freeone]

Re: Dell 2007WFP Won't Power On

I just found that a diode is reading very low in diode mode(0,057 in both directions), is it faulty? What type of diode it can be? Thanks!

It turns out that the diode when desoldered, works fine, so it's just my fault.

[elsayed]

Re: Dell 2007WFP Won't Power On

[QUOTE=peterfares;118000]Hello,

I am measuring the voltage at the connector going to the logic board. It is showing 18V across the pins in the picture. None of the other pins show voltage relative to any of the other pins on the connector.

There is one fuse I found on the power supply and it has no resistance across the ends.

I will upload more, higher quality photos tomorrow.

Thank you![/QUOTE

[gordesky1]

Re: Dell 2007WFP Won't Power On

hey guys i hope someone can help me.. I bought this monitor back in 2007 new and never had a issue with it till these last 2 months.

sometimes when you shut it off or goes in sleep mode than power it back on it would flicker for like 5minutes till it warms up and it fine but it kept on working till 4 days ago... I woke up and saw the screen was off but wouldn't come back on but the power light is on and the input light is lit but it wouldn't move too other inputs when you push the button.

The power works cause i can turn it on and off but yea no display at all no light from it either or even doing the flashlight trick too see if anything on the screen it shows nothing..

So i open it up and found 3 bulge caps on the inverter board http://prntscr.com/j4fplg so i ordered new caps with matching specs and soldered them on today..

welp turning it back on i get no display still but the input button was working than all sudden it got suck on 3 and quit working again..

Would anyone know what the issue would be? the 3 other boards even the usb board looks fine no bulgeing caps or anything..

The monitor does have 100k hours on it or pretty close too it so i wonder if the lcd panel gave up? than again i would think it would show a image on the screen with out the black light and the inputs would work still too..

i checked the fuse on the inveter board and im getting 19volts but when no power too it i get no readings or even a beep from it. checked the fuses on the other boards and i get a beep from them from my meter.

[gordesky1]

Re: Dell 2007WFP Won't Power On

Hmm turns out i am getting a very dark image on the screen now and buttons are working now... i shined a bright flash light on it and hooked it up too my laptop and yep i see the window moving around on it. But now im wondering is it a problem with the inverter or the ccfl... Tho i do noticed the inverter is not even warm and i know they do get warm too hot. I just cant find anything wrong with the inverter... i mean at first yea the bad caps but i replaced them and still nothing..


Im seeing on another thread https://www.badcaps.net/forum/showthread.php?t=8603 about connecting too pin 10 than too a led than too ground ?

[marce002]

Re: Dell 2007WFP Won't Power On

Hi guys,
I'm having two of these monitors (2007wfpb) and they both failed their USB boards. On one of them the USB board was kind of working as it was flickering its voltages up and down (it was not able to power up the LCD at all), but this behaviour helped me to measure the voltages that are needed and are going out of it.
Anyway, if your logic board is alive, you need all 3.3V, 5V and 12V to be fed to the logic.
I gave it a try using a spare computer PSU as it has all required voltages.
So I fed them to J8 as shown in the following diagram:
---------
| X | X | You should not connect anything to the X places!
---------
| X | 12|
---------
|3.3| 5 |
---------
| X | G | G is GROUND
---------
| X | X |
---------
| X | X |
---------

In the end, both monitors are working fine, except they need an external computer PSU

P.S. I hope I can find a solution with 7805, 7812 and something for 3.3V in the future, so I can get rid of these PC PSUs.

Insanezz please can you show us where to connect the 3.3v 5v and 12v ( from external psu ) to the main board? I have removed both u13 and u5 regulators but can understand that using an external power like you i will not need them....

[marce002]

Re: Dell 2007WFP Won't Power On

Hi guys,
I'm having two of these monitors (2007wfpb) and they both failed their USB boards. On one of them the USB board was kind of working as it was flickering its voltages up and down (it was not able to power up the LCD at all), but this behaviour helped me to measure the voltages that are needed and are going out of it.
Anyway, if your logic board is alive, you need all 3.3V, 5V and 12V to be fed to the logic.
I gave it a try using a spare computer PSU as it has all required voltages.
So I fed them to J8 as shown in the following diagram:
---------
| X | X | You should not connect anything to the X places!
---------
| X | 12|
---------
|3.3| 5 |
---------
| X | G | G is GROUND
---------
| X | X |
---------
| X | X |
---------

In the end, both monitors are working fine, except they need an external computer PSU

P.S. I hope I can find a solution with 7805, 7812 and something for 3.3V in the future, so I can get rid of these PC PSUs.

Insanezz please can you show us where to connect the 3.3v 5v and 12v ( from external psu ) to the main board? I have removed both u13 and u5 regulators but can understand that using an external power like you i will not need them.... j8 in my board is empty !! 2007fpv different from yours 2007wfpv?

[komix]

Re: Dell 2007WFP Won't Power On

Insanezz please can you show us where to connect the 3.3v 5v and 12v ( from external psu ) to the main board?