Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

[Jeremy112]

Hello everyone,

I have a Dell 3007WFPT monitor here that has quite the perplexing issue for me. I'm usually pretty good with repairing Dell flat panels but this one is a beast all its own.

The issue is, when you power it up, it turns on fine, backlights come on, but the screen is black (glowing black from the backlights of course). There is NOTHING displaying, no red green blue black white, no OSD, nadda.

If I turn the monitor off, you can see it get dark, signifying the backlights are turning off as normal...

Basically, everything on this monitor is working except it actually displaying something.

I have fully recapped the power supply with brand new nichicon capacitors, also replaced the main control board (the one attached to the panel itself with the 4 ribbon cables). The only boards left are the inverter, USB/memory card board, and the video input board.

I have not done anything with the video input board based off the fact that the DVI connection goes straight to the control board (no ICs or anything besides SMD coils).

Anyone who knows something about this monitor and has some advice would greatly be appreciated.

[selldoor]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

There are quite a few threads on this monitor - have you read them? not that I recall this particular problem.
Do the back lights stay on ALL the time?
Does the power light stay the same colour all the time.?

Checked the fuses on the Tcon board?

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Hello selldoor,

I did read through quite a bit of those threads but as you said, this issue wasn't in any of those threads.

The backlights stay on all the time until I power the monitor off. the power LED stays blue until I power it off.

And regarding the Tcon board, as I said I replaced that board with a known good Tcon board, no affect.

I did just notice that there is a 2nd cable coming from the video input board going to the Tcon board, so maybe the video board is at fault?

[selldoor]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

whoops I was thinking about 2007WFP
I will have another read ans start again though checking fuses is a basic.
Probably has some smd ones on one of the boards with a G on.

Also if you can post pictures of your boards might helps us

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

whoops I was thinking about 2007WFP
I will have another read ans start again though checking fuses is a basic.
Probably has some smd ones on one of the boards with a G on.

Also if you can post pictures of your boards might helps us

No problem, I can get some pics added in a bit here. I did check all the fuses (Even the FBxxx ones) Every actual fuse, and FB fuse checks out fine sadly

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Pic of the input board (the only board that has not been repaired/replaced)

I didn't take pics of the inverter or Tcon because I know they aren't the issue since I have more than one on hand that I know are good boards.
Anyway:

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Also, forgot to add, no photo of the bottom of the board because there is nothing on the bottom at all.

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

I wanted to add something, I was reading this thread here: https://www.badcaps.net/forum/showth...hlight=3007WFP

I noticed this guy had the same exact issue as me, all he did was replace all the capacitors on his power supply and repair the fuse on his Tcon board and his image came back.

I however have 2 good Tcon boards still, so I am wondering if there is something on the power supply yet?

I checked some Diodes on the bottom of the power supply board, and one Diode ( D100 ) reads 0.068 both ways, the rest of them do not read one way, and read .600 as they should.

Below is a photo of the bottom of the Power supply (the section in question)

[selldoor]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Hi - I read that thread too and yes the problem seemed similar. Looks like a couple of resistors in parallel with the diode so you will need to remove to check properly.
Looked at the picture of the other suspect board - looks like 1 voltage regulator
U something perhaps check that. Is that a usb socket near the GG fuses? if so they are
probably just to protect from bad plugging in.

[Davi.p]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Some confusion here... You called Tcon 1 time Main control b. 1 time Tcon b.,
but Main control board is another good name for video input board..
i've read the example thread for some posts and it don't seem so similar to this issue, so you have changed the Tcon but this seems to me a video input board problem.

[Jeremy112]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

Some confusion here... You called Tcon 1 time Main control b. 1 time Tcon b.,
but Main control board is another good name for video input board..
i've read the example thread for some posts and it don't seem so similar to this issue, so you have changed the Tcon but this seems to me a video input board problem.

Hello Davi,

I would agree, but when connected to a PC, the monitor is detected and I can control the resolutions as would be normal, I just don't actually see anything on the screen besides the glow from the backlights.

The Tcon board, I referred to as the control board because on the Tcon it says control board, sorry for the confusion. To further clarify I am referring to the board that has the 4 ribbon cables going from it to the LCD panel itself.

The example thread the guy is saying he has the same issue, his backlights work, monitor powers on and off as normal, he can see his backlights, but there is no OSD or any display from the video input. He replaced all of his capacitors on his power supply, and the fuse on his Tcon (board with 4 ribbon cables to the LCD panel) board, and his monitor displayed again like it should. He was just further going on with the repair about a buzzing capacitor (of which I am not having any of that, my monitor is dead silent).

I will check out the diode out of circuit and report back when I have a chance, I have a load of projectors coming in this week so I don't know how much time I will have to work on it until the weekend. It would sure be nice to see this beauty display again, the monitor is in excellent cosmetic condition, would be a shame to see it go unrepaired.

[budm]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

OK. so the fuse on the T-CON is good, how about the DC voltage reading on the fuse with ref to the chassis, it should be either 5V or 12V depends on the panel, this voltage is fed through a switched MOSFET on the main board.

[Davi.p]

Re: Dell 3007WFPT - Comes on - Blank screen - Backlights work - Help please

I would agree, but when connected to a PC, the monitor is detected and I can control the resolutions as would be normal

That don't seems abnormal to me.. i think is possible (i don't remember example schematics) that some pins of the vga conn. is connected directly to the eeprom that stores EDID data (monitor parameter/infos for PnP), so the main chip could also be bad, or are bad some voltage regulators.

The Tcon board, I referred to as the control board because on the Tcon it says control board

Tcon= Timing controller board, so please refer as Tcon

The example thread the guy is saying he has the same issue, his backlights work, monitor powers on and....

I quote his post:

If I connect a DVI input (PC), the power led turns amber.

This doesn't happen to you.. and:

As an added note, in the past (once every few months) when the monitor would resume from sleep, I have had the whole screen filled with vertical lines

this also..

I will check out the diode out of circuit and report back

I know that diode will test good, you was measuring parallel resistors. (62ohm total).