Dell 2005FPW Power whine and on/off issue.

[gireal]

I have a Dell 2005FPW AO3 revision monitor that has started having the familiar power on/off issue after a short period of operation.

The monitor works after cold start for 10-30 minutes, then begins to emit a high pitched squeal. It can continue to operate after the noise begins for roughly an hour. It will then enter a power cycle on and off with the backlight clicking on and off until physically unplugged. During this behavior the power buttons are unresponsive and no image is displayed during its short power on. If you power it off when the noise begins it immediately starts the power cycle when turned back on.

After it rests while unplugged it will work again for 10-30 minutes and the behavior repeats.

One interesting note is that if the two wide connectors, visible in the side - LCD power connectors image, are disconnected the monitor can be powered up immediately after it began its cycle, emits no noise, is properly lit and displays output properly, but turns off after one to two seconds.

All the capacitors appear to be Sam Young 105c, at least the ones I can read. The PCB is unmarred by scorching and the capacitors are not obviously leaking or domed, but there are many covered in white goop.

I have a soldering iron and am confident enough to clip the caps and resolder them, but not sure what capacitor brands/types to replace them with or which ones are stand out culprits.

[retiredcaps]

Re: Dell 2005FPW Power whine and on/off issue.

1) Those are excellent photos.

2) Can you post another photo with the connectors all plugged in?

3) What happens if you lower the brightness and contrast from the factory default to 25/25? Does the monitor stay on longer?

4) The whine could be coming from the ccfls. As they age, they draw more power.

5) Pictures of bad ccfls are provided by budm.

http://s807.photobucket.com/albums/y...klight%20lamp/

[gireal]

Re: Dell 2005FPW Power whine and on/off issue.

1. Thanks

2. Yes, also uploaded an image of the logic board front (removing it requires undoing a lot of usb fittings). I can take it out if the back needs to be seen for traces.
Also uploaded pictures of two cables that are difficult to have connected and handle the camera for pictures. The power pcb to logic board power cable and the logic board to lcd panel cable, wires and plugs.

3. Yes, it does. If you drop the brightness to 0 it lasts significantly longer. Raising it over 65 brightness results in it shutting off immediately.

4. There's no obvious arcing from ground as seen in some of the example images, but I haven't taken the panel apart yet since it's much more involved. I'll do it this evening and compare it to the darkened end ccfl images. If it's just that then I'm relatively relieved.

[Toasty]

Re: Dell 2005FPW Power whine and on/off issue.

Just recap the entire PSU and see how it goes. It's not a big deal.

Provide cap sizes & values please. You'll be looking to spend <$20 to do the whole unit.

Don't need to involve the large mains cap unless you want to. It's not a "common" failure.

Toast

PS: I've successfully used FM, PW, FC, HE, capacitors in these units.

[retiredcaps]

Re: Dell 2005FPW Power whine and on/off issue.

In red, I circled what I think are the secondary inverter transformer windings.

With power off and lcd unplugged, measure the resistance between the 2 red circles. Do this for every inverter transformer and report all the readings (I didn't mark up the rest in paint, but you get the idea). You should have 6 readings in total.

All 6 should read within 3% of each other.

[gireal]

Re: Dell 2005FPW Power whine and on/off issue.

I measured the pins indicated with a Greenlee DM-200 Digital multimeter and the resistance for the two indicated pins was found out of range for all six sets.

The resistance for the points directly to the right of the indicated pins (For the blue caps) had identical resistances at 3.89Mohms.

Attached are images of the CCFL tubes. They do have varying signs of the dark black rings.

[budm]

Re: Dell 2005FPW Power whine and on/off issue.

Not sure if this is the same problem you are having, I fixed this in 2010 but I do not remember the notes I have in my pictures but you can try out the cap, also make sure to re-solder the pins on the AC inlet connector.
More pictures here also:
http://s807.photobucket.com/albums/y...ell%202005FPW/

[retiredcaps]

Re: Dell 2005FPW Power whine and on/off issue.

I measured the pins indicated with a Greenlee DM-200 Digital multimeter and the resistance for the two indicated pins was found out of range for all six sets.

Then I incorrectly identified the pins. What is the part number of the transfomer?

Attached are images of the CCFL tubes. They do have varying signs of the dark black rings.

They don't look too bad to me. You still could have internal wiring/solder problems between the return wire (the thinner guage) and the actuall ccfl.

I picked a monitor where the owner complained it would work for 20 minutes and then go off. The bulbs looked okay, but the wiring covered up by the silicon ends was totally frayed.

Hmm, you have 2 other experienced members suggesting a recap which might also solve your problem.

If you have a multimeter, you could measure the voltages when it is working and not working and do a comparison. That might help dictate which way to proceed? At least it is better than no suggestions.

[budm]

Re: Dell 2005FPW Power whine and on/off issue.

@retiredcaps, I ran into lamps look OK but just to find out later that the wire as you describe was just touching the end of the lamp or close to the end of the lamp to cause the arc the be enough the light up the lamp but you can hear faint arcing sound and arcing stop when the lamp gets warm enough expansion to get a little better contact with the wire. I turn off all the light and I see arcing in the dark. You have pull a little bit on the wire to see if they will come right out. Now I use AM radio tuned to the low end where there is not radio station and put it close to LCD panel, you will hear steady noise if the lamps are working but arcing will sound splattering (a little hard to explain).
I also use the radio for locating loose wiring, bad switches, especially at the breaker box,

[retiredcaps]

Re: Dell 2005FPW Power whine and on/off issue.

Now I use AM radio tuned to the low end where there is not radio station and put it close to LCD panel, you will hear steady noise if the lamps are working but arcing will sound splattering (a little hard to explain).
I also use the radio for locating loose wiring, bad switches, especially at the breaker box,

Hmm, I never would have thought of that. Bookmarking this post for sure.

[gireal]

Re: Dell 2005FPW Power whine and on/off issue.

Prompted by the comment about the wiring ends I dug out the camera for a larger look at the covered sections and it turns out the cabling has melted right where it enters the plastic end cap and there's slight scorching on the plastic harness for both sets of lights.

[retiredcaps]

Re: Dell 2005FPW Power whine and on/off issue.

it turns out the cabling has melted right where it enters the plastic end cap and there's slight scorching on the plastic harness for both sets of lights.

Alexanna is the king of this type of repair. He has had success stripping off the bad wiring and resoldering it to the ccfl. I tried it once myself and gave up.

A tutorial is at

http://www.ccflwarehouse.com/lasotu.html