Dell 2007FPb Not coming on

[billy66]

I have a Dell 2007FPb which shows no power or LED lit. I have the fortune of having two of these... so due to board swapping, I've narrowed it down to the main/logic board and the USB add on board as being bad. I have voltage coming into the logic board (19V) but nothing on it. Here is what I've found so far, and would love some help on where else to look:

Q6: Pin 1 to 3 show 43 ohms
Pin 1 to 4 show 43 ohms
Pin 3 to 3 show 0 ohms

Q6 is the same parts as Q9 and Q14... but these all have OL for those same readings... so I assume that Q6 is shot


U13: Pin 1 to 3 show 0 ohms
Pin 1 to 4 show 17 ohms
Pin 3 to 4 show 17 ohms.

Believe this is bad.


U5: Pins 1 to 2 show 0 ohms
Pins 1 to 3 show OL
Pins 1 to 4 show 0 ohms
Pins 2 to 3 show OL
Pins 2 to 4 show 0 ohms
Pins 3 to 4 show OL

Not sure if that is good.

F19 is open.


There are a couple of componets that I have no idea on what they are... FD3, FD4, FD5, FD6, FD7, and FD8... some are reading different from each other. So I assume some are bad? But have no idea what they are. Only says: S4 04 on them.

And where I'm most lost is that voltage comes in at the connector at the top of the logic board... 7 pin connector. I have 19vs on the two right pins... as I do on the good monitor... but after that I can only trace it to the interconnect between the two boards (where it then goes to the fuse F19) and if I follow it on the logic board, it goes all the way left to U12... but can't follow it any further. Not sure if it goes anywhere else...

Any help would be wonderful.

Thanks

[bonney]

Re: Dell 2007FPb Not coming on

So you have one bad logic board and one bad usb board ?

Q6 has only 3 legs

[billy66]

Re: Dell 2007FPb Not coming on

So you have one bad logic board and one bad usb board ?

Q6 has only 3 legs

Yes. The logic board and the usb board are both bad.

Q6 has 3 legs... I was counting the little stub in the center as a leg...

[bonney]

Re: Dell 2007FPb Not coming on

I have number the legs on the picture

[jetadm123]

Re: Dell 2007FPb Not coming on

The usb card on the right, try checking the 3A fuse (F1?) that's right above the cap that is next to the 6-prong connector. IIRC, if this fuse is bad, then it will prevent the power supply from starting.

[billy66]

Re: Dell 2007FPb Not coming on

I have number the legs on the picture

Leg 2 that is by itself, I called 4...

[billy66]

Re: Dell 2007FPb Not coming on

The usb card on the right, try checking the 3A fuse (F1?) that's right above the cap that is next to the 6-prong connector. IIRC, if this fuse is bad, then it will prevent the power supply from starting.

That fuse is F19, and it is bad. I'm more worried about the logic board, as it is harder for me to follow. Also, the FD's... on the USB board... not sure what they are, or how to test them. I get different readings for some of them.

[alexanna]

Re: Dell 2007FPb Not coming on

That fuse is F19, and it is bad. I'm more worried about the logic board, as it is harder for me to follow. Also, the FD's... on the USB board... not sure what they are, or how to test them. I get different readings for some of them.

Billy66,
with an ohmmeter check both sides of F19 for a low ohm reading to a ground screw.
Al.

[bonney]

Re: Dell 2007FPb Not coming on

Leg 2 that is by itself, I called 4...

2 and 2 are both the same

[ecking767]

Re: Dell 2007FPb Not coming on

That fuse is F19, and it is bad. .

That not a USB board. Its a DC to DC converter board. With F19 blown your monitor wont turn on. Before replacing the fuse check for shorts across those MOSFET.

[bonney]

Re: Dell 2007FPb Not coming on

Is this the one thats suffers from faulty eeprom? Billy what is U13

[billy66]

Re: Dell 2007FPb Not coming on

I'll have to look at it in a week... I left it at work, and I'm on vacation for the week. I'm not sure about the eeprom issue. I do believe I've found some bad components... just not wanting to order/replace them without knowing if I got most/all of it... so to not ruin the new stuff.

[retiredcaps]

Re: Dell 2007FPb Not coming on

There are a couple of componets that I have no idea on what they are... FD3, FD4, FD5, FD6, FD7, and FD8... some are reading different from each other. So I assume some are bad? But have no idea what they are. Only says: S4 04 on them.

If you Q6 is shorted, check the FDs (they look diodes) to see if they are shorted as well. Especially the ones that feed Q6.

[koru]

Re: Dell 2007FPb Not coming on

Hello there,

Firstly; what a great forum! I have a Dell 2007fpb that has exactly the same issues as this thread; so i thought it was best to continue here.
I bought a copy of a 'LCD repair' manual online and its helped me get going + the great posts here have helped immensely.
As it has been a few years since the original post, this is the issue:

The Problem
The monitor when plugged in (both mains and vga input) is completely dead; no power light on the front lights up.

What I have figured out
The power board is outputting 19v and seems OK

USB/Power Board
Going by some other related posts I have checked for voltages on testpoints TP31-38; these are my readings:

TP31 18.93v
TP32 0v
TP33 0.5v
TP34 0v
TP35 0.15v
TP36 0v
TP37 0.67v
TP38 0v

fuses F19 and F1,F2, F3 & F4 all read <1 ohm so look good.


The main board
There are three things here that look suspect

1. I noticed someone has cut a PCB track when unscrewing a screw, i have managed to solder this cut and continuity check
2. Near the 12-pin and 7-pin connectors U5 looks 'shiny black' and the part number is not visible - possibly overheating?
3. Also near this is U13; this has a short between pins 1 and 2 and on the underside of the board its showing some discolouring; again probably overheating?

My main questions are:

1. When i test for voltages on the boards, what do i need connecting? E.g. mains power, vga input, power board connected to main board with usd/power board attached etc etc? will the circuit fire up without the backlights and lcd connected for example?
2. From the 2007 strip-down post, it looks like U5 is a 2.5v linear regulator; how would i find out the part number please?
3. What else should i be checking before i replace U5, U14?

I have uploaded pics of the main and usb/power board front and back.

Many thanks!

[budm]

Re: Dell 2007FPb Not coming on

Did you look here yet for the voltage and IC testing. You do have to have USB hook up.
https://www.badcaps.net/forum/showth...t=dell+2007fpb

[koru]

Re: Dell 2007FPb Not coming on

Hi,
I should have confirmed that i am not getting any voltages out of the voltage regs; just the 19v from the power board. these are some test results I have got:

USB/Power Boards

Diodes (using diode test function on DMM)

FD3 0.142/0.323
FD4 0.141/0.323
FD5 0.151/1.395
FD6 0.151/1.397
FD7 0.148/0.804
FD8 0.148/0.804

Voltage Reg?

U2 no shorts between pins

Transistors? J598

Q6 no shorts
Q14 No shorts
Q9 no shorts


Main Board

U13 Pin 1-2 short (1.5ohm)
Pin 1-3 126 ohm

U5 1-2 126 ohm (does anyone know what part number this is please as its blackened)
no other shorts


So aside from the components that are suspect (U13 and U5) what can i conclude about the state of the other components please?
thanks again!

[jetadm123]

Re: Dell 2007FPb Not coming on

If you looked at budm's link:

U5 is a 2.5V voltage regulator, part # 950T65

[koru]

Re: Dell 2007FPb Not coming on

Thanks for that confirmation Jetadm123