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Old 01-02-2010, 10:20 PM   #1
aliasdck
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Default Dell 2007WFP - Inverter Problem?

My brother gave me this monitor after it stopped working for him in hopes I could repair it and find it a new home.

The display turned on when I hit the power button for about a second and then immediately went dark. It appeared the backlights were shutting down because the monitor continued to function as I could see the desktop using a flashlight.

So I suspected there was a problem in the inverter or one of the ccfl's.

There were five electrolytic capacitors on the inverter board:

(3) 220uF 25V Elite capacitors
(2) 47uF 25V Lelon capacitors

I went ahead and tried replacing the 3 Elite caps with some panasonic FC's I had lying around but this didn't change anything. I dont have anything to replace the 2 Lelon caps with, but I do plan to replace all caps in this monitor at one point.

Then I measured the 3 inverter transformers and everything seemed ok there.

Next I tried resoldering all the legs of the inverter transformers and surrounding devices just incase there were any bad solder joints. Still no improvement.

I noticed the inverter is using the oz964gn pwm controller chip. Working from past experience, I temporarily installed an LED From pin 10 to ground. This forces pin 10 (Voltage Control Loop Compensation Pin) to around its nominal operating voltage. If I understand correctly, this fools the chip into believing there is no problem (ie over/under voltage or current) in the inverter.

Here is the data sheet incase anyone wanted to see it: http://pdf1.alldatasheet.com/datashe...C/OZ964GN.html

Anyways, by installing this LED, I was able to get the monitor to work properly. This leads me to believe that there is a problem in the inverter... either a over/under voltage or current condition OR a false positive for one of those conditions due to a problem in the detection circuitry. Not sure which one it is, but I figured it would be worth mentioning that with the LED installed, the Monitor operates wonderfully i.e great picture and great illumnination.

So that all brings me to where I am at now... due to how this monitor is assembled, I can't really be making any online readings so further troubleshooting is going to be difficult.

Anyone have any ideas? I suppose it could be that one of the ccfl's is getting old and just pulling to much current but I'm not sure how to go about determining this. Or should I try replacing the 2 Lelon caps?

I have included top and bottom picture of both the inverter and power supply. Not the best quality but I suppose they are better than nothing. You'll notice a jumper wire installed on the inverter - that runs out to the LED I was talking about.

Any advice is appreciated.
Attached Images
File Type: jpg InverterTop.jpg (132.1 KB, 292 views)
File Type: jpg InverterBottom.jpg (120.4 KB, 204 views)
File Type: jpg PowerTop.jpg (111.4 KB, 265 views)
File Type: jpg PowerBottom.jpg (124.0 KB, 189 views)
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Old 01-02-2010, 10:42 PM   #2
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Default Re: Dell 2007WFP - Inverter Problem?

Quote:
Originally Posted by aliasdck
My brother gave me this monitor after it stopped working for him in hopes I could repair it and find it a new home.

The display turned on when I hit the power button for about a second and then immediately went dark. It appeared the backlights were shutting down because the monitor continued to function as I could see the desktop using a flashlight.

So I suspected there was a problem in the inverter or one of the ccfl's.

There were five electrolytic capacitors on the inverter board:

(3) 220uF 25V Elite capacitors
(2) 47uF 25V Lelon capacitors

I went ahead and tried replacing the 3 Elite caps with some panasonic FC's I had lying around but this didn't change anything. I dont have anything to replace the 2 Lelon caps with, but I do plan to replace all caps in this monitor at one point.

Then I measured the 3 inverter transformers and everything seemed ok there.

Next I tried resoldering all the legs of the inverter transformers and surrounding devices just incase there were any bad solder joints. Still no improvement.

I noticed the inverter is using the oz964gn pwm controller chip. Working from past experience, I temporarily installed an LED From pin 10 to ground. This forces pin 10 (Voltage Control Loop Compensation Pin) to around its nominal operating voltage. If I understand correctly, this fools the chip into believing there is no problem (ie over/under voltage or current) in the inverter.

Here is the data sheet incase anyone wanted to see it: http://pdf1.alldatasheet.com/datashe...C/OZ964GN.html

Anyways, by installing this LED, I was able to get the monitor to work properly. This leads me to believe that there is a problem in the inverter... either a over/under voltage or current condition OR a false positive for one of those conditions due to a problem in the detection circuitry. Not sure which one it is, but I figured it would be worth mentioning that with the LED installed, the Monitor operates wonderfully i.e great picture and great illumnination.

So that all brings me to where I am at now... due to how this monitor is assembled, I can't really be making any online readings so further troubleshooting is going to be difficult.

Anyone have any ideas? I suppose it could be that one of the ccfl's is getting old and just pulling to much current but I'm not sure how to go about determining this. Or should I try replacing the 2 Lelon caps?

I have included top and bottom picture of both the inverter and power supply. Not the best quality but I suppose they are better than nothing. You'll notice a jumper wire installed on the inverter - that runs out to the LED I was talking about.

Any advice is appreciated.
There are a couple of ways to approach this. I'm going to need better pictures of the inverter to be able to help much, but here is the rough idea.

The inverter has circuitry that senses the output voltage and current through each CCFL. This information is combined and fed to one or more inputs of the Inverter Controller. Typically they use a pair of capacitors in series and a diode as a voltage divider to sense the voltage, and a resistor / diode network to sense the current on the return line. By tracing the circuitry, you can locate points where you can measure the signal from each CCFL.

One shortcut is to look at the leads to the CCFLs. Often you will see a large diameter pink or blue wire paired with a smaller diameter white wire. (The wires are actually the same gauge, the difference is due to the heavier insulation on the high voltage line to the CCFL. The return line is at a much lower voltage and needs less insulation.) In most cases the contacts on the CCFL connectors can be probed on the PC board. With the backlights operating, measure the voltage on the return lines (NEVER on the drive lines).

Possible causes include shorted turns on a transformer, an open primary or secondary, a bad solder joint or broken wire at the CCFL on either the drive line or the return line, deteriorated insulation on either line, or a bad component in the sense circuitry.

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Old 01-03-2010, 12:54 AM   #3
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Default Re: Dell 2007WFP - Inverter Problem?

Ugh. Well...

I decided to try measuring the values on the return ccfl lines. This is where things got interesting.


As I was about to take these readings I began to hear something arching. The air was filled with a very clean like smell - reminds me of the way those ozone generators/air cleaners smell. I would also like to mention that I had noticed this smell several times before while working on this monitor - though I hadn't thought much of it. Only this was the first time I actually heard this arching noise.

I quickly looked inside the side of the monitor and saw some arching occuring around one of the pins of the transformer (circled in red... not exactly sure that is where the arching was occuring because it all happened so fast).

Anyways, I decided to try and desolder the transformer in order to get a good look at it, but unfortunetly, I accidentally damaged it beyond repair while removing it I'd like to mention this transformer was extremely hot just after the arching while the other two where still room temparture.

So, I'm going to need to replace the transformer whether or not it was bad to begin with. For the record, it measured nearly identical in resistance (while in circuit) to the two other transformers.

It is marked as: 4001r616 002. Tried searching for 4001r but haven't found anything.

I can try and get some better pictures if need be though it may take a few days to arrange that.

Last edited by aliasdck; 01-03-2010 at 01:03 AM..
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Old 01-03-2010, 07:59 AM   #4
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Default Re: Dell 2007WFP - Inverter Problem?

Quote:
Originally Posted by aliasdck
Ugh. Well...

I decided to try measuring the values on the return ccfl lines. This is where things got interesting.


As I was about to take these readings I began to hear something arching. The air was filled with a very clean like smell - reminds me of the way those ozone generators/air cleaners smell. I would also like to mention that I had noticed this smell several times before while working on this monitor - though I hadn't thought much of it. Only this was the first time I actually heard this arching noise.

I quickly looked inside the side of the monitor and saw some arching occuring around one of the pins of the transformer (circled in red... not exactly sure that is where the arching was occuring because it all happened so fast).

Anyways, I decided to try and desolder the transformer in order to get a good look at it, but unfortunetly, I accidentally damaged it beyond repair while removing it I'd like to mention this transformer was extremely hot just after the arching while the other two where still room temparture.

So, I'm going to need to replace the transformer whether or not it was bad to begin with. For the record, it measured nearly identical in resistance (while in circuit) to the two other transformers.

It is marked as: 4001r616 002. Tried searching for 4001r but haven't found anything.

I can try and get some better pictures if need be though it may take a few days to arrange that.
Ouch!!! This is definitely a 'locking the barn door after the horse is gone' response, but removing the transformer is quite easy if you use Chip Quik. That may be academic, however. The most likely cause of the arcing was a break in a winding of the transformer.

Who manufactured the inverter? There are several sources for inverters and transformers.

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Old 01-03-2010, 11:52 AM   #5
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Default Re: Dell 2007WFP - Inverter Problem?

The inverter board pn is 5EL2J04011 (from a sticker on the back) and has 4H.L2J04.A01 etched on the front.

The transformer is marked like this:

1J.26061.001
4001R616 002

All I've been able to find so far is this:

http://www.lcdrepair.us/2007fp-inverter.html

After shipping it's going to cost me a little over $70. That's not such a bad price but I can't afford that right now.

I'm hoping I can find the transformer somewhere but so far I haven't had any luck tracking one down.
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Old 01-03-2010, 01:45 PM   #6
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Default Re: Dell 2007WFP - Inverter Problem?

Sorry. I made a mistake and asked for the thread name change. I thought the name of this thread should be 2007FPW instead of 2007WFP. Why Dell would change their naming convention after several years escapes me...? Even the replacement parts site shows your part as belonging to a 2007FPW.

My apologies.

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Old 01-08-2010, 09:34 PM   #7
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Default Re: Dell 2007WFP - Inverter Problem?

I found a replacement transformer... not an exact match but apparently close enough.

Anyways, I installed it and the monitor still suffered from the same problem - the backlights turn off after a couple of seconds.

I decided to take some voltage readings on the ccfl return lines. All return lines are registering 0 Volts AC on my multimeter expect for one line which is reading about 60mV (while the backlights are on). (What kind of readings should I be expecting?)

As I was taking those readings I accidentally bumped the insulation on the wire of one of the big ccfl lines with my probe and I noticed that the insulation right at the point of contact began to glow bright purple! Sure enough, that was the line associated with the return line that was reading 60mV. This ccfl was also connected to the transformer that is overheating. This did not occur on any other line I tried it on.

I tried rearranging the ccfl lines so that they were connected to different transformer outputs and the symptom always followed that specific ccfl regarldess of where it was connected.

So I'm left to assume I have a faulty ccfl.

I disassembled the monitor further in order to have a better look at the tube and its wiring. I looked closely under a magnifying glass at the entire length of wire and cannot see any point where the insulation may be problematic.

At this point I cannot afford to buy new ccfl's for this monitor so I think I'm going to set it aside for now.
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Old 03-08-2010, 10:23 AM   #8
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Default Re: Dell 2007WFP - Inverter Problem?

If you've given up on this project, let me know. I am in need of a CCFL inverter exactly like you have right now.
Let me know if you would like to make a deal.
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Old 03-08-2010, 02:28 PM   #9
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Default Re: Dell 2007WFP - Inverter Problem?

Quote:
Originally Posted by theurgy
If you've given up on this project, let me know. I am in need of a CCFL inverter exactly like you have right now.
Let me know if you would like to make a deal.
I ended up desoldering the other two transformers off the inverter board and used them to fix another monitor... so I'm sorry to say I no longer have the inverter board.
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Old 03-08-2010, 05:22 PM   #10
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Default Re: Dell 2007WFP - Inverter Problem?

10-4 rubber ducky!
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Old 03-17-2011, 01:02 PM   #11
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Default Re: Dell 2007WFP - Inverter Problem?

Hi there, Im looking for someone who know the value of the ZD701 little zener diode, because mine is blown and I cant find the breackdown voltage nowhere...
If you have an inverter board of the 2007WFP/FPB an will to help me, please measure the voltage drop on this little zener while the monitor is on putting the voltimeter on the terminals of the zener.
Thanks in advance
And sory to bring back old posts
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Old 07-16-2015, 11:28 AM   #12
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Default Re: Dell 2007WFP - Inverter Problem?

Quote:
Originally Posted by aliasdck View Post
I noticed the inverter is using the oz964gn pwm controller chip. Working from past experience, I temporarily installed an LED From pin 10 to ground. This forces pin 10 (Voltage Control Loop Compensation Pin) to around its nominal operating voltage. If I understand correctly, this fools the chip into believing there is no problem (ie over/under voltage or current) in the inverter.

Here is the data sheet incase anyone wanted to see it: http://pdf1.alldatasheet.com/datashe...C/OZ964GN.html

Anyways, by installing this LED, I was able to get the monitor to work properly. This leads me to believe that there is a problem in the inverter... either a over/under voltage or current condition OR a false positive for one of those conditions due to a problem in the detection circuitry. Not sure which one it is, but I figured it would be worth mentioning that with the LED installed, the Monitor operates wonderfully i.e great picture and great illumnination.
You my friend, are amazing. I had a spare LED lying around, soldered it onto the pins you described and voila I get the screen going. From the cracking coming from the top left CCFL (when looking at the front of the screen) I am almost certain it is the ccfl. Im not condifent enough to change it even though I have a spare, especially because the spare is a 2 bulb (I am assuming this one has a 3 bulb because of the 6 wires from the inverter).

This gave me unlimited monitor time to adjust the brightness to a level where the ccfl wasn't complaining (at the moment 100% as opposed to partial brightness).

Thank you once again, you saved me so much time and money.
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Old 07-16-2015, 12:35 PM   #13
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Default Re: Dell 2007WFP - Inverter Problem?

Datasheet OZ964:
Page 5:
The current control loop monitors CCFL current
that is sensed with a voltage at FB (pin 9). The
voltage at FB (pin 9) is input to an Error Amplifier
and the output, CMP (pin 10), regulates the
CCFL current.
Attached Files
File Type: pdf OZ964.pdf (327.5 KB, 79 views)
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Old 07-21-2015, 02:26 AM   #14
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Default Re: Dell 2007WFP - Inverter Problem?

Quote:
Originally Posted by haydster7 View Post
You my friend, are amazing. I had a spare LED lying around, soldered it onto the pins you described and voila I get the screen going. From the cracking coming from the top left CCFL (when looking at the front of the screen) I am almost certain it is the ccfl. Im not condifent enough to change it even though I have a spare, especially because the spare is a 2 bulb (I am assuming this one has a 3 bulb because of the 6 wires from the inverter).

This gave me unlimited monitor time to adjust the brightness to a level where the ccfl wasn't complaining (at the moment 100% as opposed to partial brightness).

Thank you once again, you saved me so much time and money.
There's no way around it, you need to replace the CCFL\wiring if it is arcing and crackling otherwise it will only burn out faster and make the problem worse anyway (possibly damage the panel or reflector sheets etc)

It's a delicate process to do the replacement, but not too bad if you go slowly and carefully. You can get new lamps cheaply on eBay from China etc.

http://www.laptoprepair101.com/repla...ght-ccfl-lamp/ shows the general idea.
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Old 09-12-2015, 02:57 PM   #15
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Default Re: Dell 2007WFP - Inverter Problem?

i have the same monitor actually 2 monitors
one with a dead power supply board
and the other have the same problem I've tried replacing cc-fl inverter board, caps seems fine
i assume it's something with the 5v to data board or something in it anyway
because with or without ccfl,inverterboard the monitor act the same
can it be a bios problem !! ?
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Old 09-12-2015, 04:01 PM   #16
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Default Re: Dell 2007WFP - Inverter Problem?

Which exact problem do you have? There are several posted here already.
If you can, please post good photos of the monitor\boards etc. The ones already posted are not that great.

Does the monitor with the dead PSU work if you swap the PSUs around?
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Old 09-13-2015, 03:05 AM   #17
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Default Re: Dell 2007WFP - Inverter Problem?

i have 2 inverterboards
2 power supply board
2 display panel
1 control board the other is burnt
1 usb and speaker power board which i think it's the problem
what i'm facing is light start up one second or 2 then off again power led on and off randomly
I've tired allot of swaps nothing new
the only thing i've found that a clicking sound from the usb board and a drop of the 5v source
i've tested everything mosfets transformers caps even reflash all ROMs
i don't have camera or picture but pictures of the same monitor is here in this forum i'll link you with this pics
DELL 2007wfpb board model 4h.l2j02. a05
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Old 09-13-2015, 03:10 AM   #18
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Default Re: Dell 2007WFP - Inverter Problem?

http://www.badcaps.net/forum/showpos...61&postcount=7
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Old 09-13-2015, 12:44 PM   #19
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http://www.badcaps.net/forum/showthr...ight=dell+2007
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Old 09-14-2015, 04:52 PM   #20
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