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Old 04-05-2017, 03:35 PM   #521
Agent24
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Default Re: Dell 3008wfp faulty power supply

The 12v, 18v and 25V rails are not likely to be active when the monitor is in standby. I assume the "Good" voltages you posted are from a running (not in standby) monitor.

Since there's no schematic, I looked at the photos posted earlier. (If you can post photos of your own boards, top and bottom, with heatsink tops of PSU removed so we can see where things go...)


I'm thinking P801 is main 5v Standby and 18v supply to the logic board
P802 is 12v as well as control signals from mainboard to tell PSU to start up etc
P803 is inverter power (25v) and also power up\DIM signal etc.


Looking at the voltages, some things seem off.

P802 Pins 7 and 9. I guess one of these is PS_ON and the other maybe inverter control passthrough from the mainboard, unless inverter has its own separate control wiring (please check)

P802 Pin 10 is strange. Need to know the function of that pin. Looks like it's driven from 5v Standby rail via Q19.

P803 Pin 13 might just be different because the monitor is not running. Hard to say.


I've added labels and pin numbers to the photo, can you confirm these are correct?
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File Type: jpg IMG_20160907_075955.jpg (1.48 MB, 22 views)
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Last edited by Agent24; 04-05-2017 at 03:39 PM..
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Old 04-05-2017, 04:42 PM   #522
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Default Re: Dell 3008wfp faulty power supply

I have used the reverse numbering for P802. That makes a bit more sense.
I have to go to work now will post some photos tonight.
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Old 04-06-2017, 05:43 AM   #523
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Default Re: Dell 3008wfp faulty power supply

Thanks for your quick reply Agent24,

Here are some snap shots of my boards. I have not taken heat sinks off at this stage because that requires de-soldering. I already did the D22 upgrade and had a good look under that heat sink. All looked A-OK to me.

Cheers
DSH
Attached Images
File Type: jpg P1070054.JPG (514.9 KB, 19 views)
File Type: jpg P1070055.JPG (507.4 KB, 15 views)
File Type: jpg P1070056.JPG (544.1 KB, 15 views)
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File Type: jpg P1070059.JPG (377.4 KB, 13 views)
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File Type: jpg P1070061.JPG (321.3 KB, 12 views)
File Type: jpg P1070062.JPG (459.5 KB, 15 views)
File Type: jpg P1070063.JPG (563.0 KB, 14 views)
File Type: jpg P1070064.JPG (575.9 KB, 15 views)
File Type: jpg P1070065.JPG (540.6 KB, 15 views)
File Type: jpg P1070066.JPG (569.6 KB, 11 views)
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Old 04-06-2017, 05:02 PM   #524
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Default Re: Dell 3008wfp faulty power supply

Thanks. Can you post a close-up of the PSU board near P802 and the SMD parts to the right of it?

Also list the part numbers of the three 8-pin ICs in that area.

I'm thinking Pin 4 of P802 is the PS_ON pin. But I need to confirm with some more detailed photos.

Last edited by Agent24; 04-06-2017 at 06:13 PM..
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Old 04-06-2017, 06:49 PM   #525
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Default Re: Dell 3008wfp faulty power supply

Just looking through the thread again to see if I can find some photos that might help, I was reminded on Page 12 about how some people have had self-destructing LVDS cables in this monitor.

I would check the LVDS cable carefully and be sure the insulation is not falling off....
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Old 04-07-2017, 04:28 AM   #526
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Default Re: Dell 3008wfp faulty power supply

I have not noticed any problems with cables at all. Double checked just now and they all look perfect. Here are some more pics of the ICs you requested.

The 2 ICs closest to P802 are labelled FP131 / 7Nc-591 (overcurrent protection)
The IC furthest away is 358A / E2550 (I guess this is AS358)

Any way I can check these?

Cheers
DSH
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File Type: jpg P1070067.JPG (436.7 KB, 18 views)
File Type: jpg P1070068.JPG (464.6 KB, 15 views)
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Old 04-13-2017, 06:11 AM   #527
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Default Re: Dell 3008wfp faulty power supply

I traced pin 4 of P802 to R103 and then to the A358 chip via a few more resistors. When viewing the chip print in the correct orientation it is the bottom right pin.

I have added some more pics of the area. Hope that helps.
Attached Images
File Type: jpg P1070096.JPG (447.9 KB, 9 views)
File Type: jpg P1070097.JPG (459.2 KB, 7 views)
File Type: jpg P1070098.JPG (397.6 KB, 6 views)
File Type: jpg P1070099.JPG (526.6 KB, 8 views)
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Old 04-13-2017, 06:30 AM   #528
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Default Re: Dell 3008wfp faulty power supply

Now I am getting confused, Pin 4 of P802 actually connects to many of the pins on A358. The resistance is 102Kohms from pin 4 to 5 of the A358 chip pins.
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Old 04-14-2017, 03:42 AM   #529
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Default Re: Dell 3008wfp faulty power supply

I think it's an LM358 dual opamp by STmicro.

I think Pin 4 of P802 controls PS-ON by pulling it LOW. So you can try shorting Pin 4 to GND with 330R resistor (just in case) and see if the PSU starts (don't have the logic board connected)

See if the voltages all come up. If it does, list all pins voltages again please.
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Old 04-15-2017, 06:31 PM   #530
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Default Re: Dell 3008wfp faulty power supply

Without the logic board connected, many voltages are out of wack and P802 pin 4 is zero volts. So I think I will have to connect the logic board to test this properly. Does that sound reasonable?
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Old 04-15-2017, 08:59 PM   #531
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Default Re: Dell 3008wfp faulty power supply

Without knowing the schematic or the fault, I can't say if that would be a good idea or not. I just don't want to risk further damage.

Maybe we should try from the other end. I have looked at the mainboard photos more in depth. I see some blown, and potentially blown capacitors. (See photos)

They may be all that's wrong, though likely there are other capacitors there which are bad and don't look it. There may also be failed voltage regulators due to the capacitors.

Hopefully they have not caused difficult to fix damage like EEPROM corruption.
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Old 04-16-2017, 12:33 AM   #532
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Default Re: Dell 3008wfp faulty power supply

Agent 24 you have excellent eyes!

The photo you are looking at has quite a bit of glare in it. Only 1 of the caps is actually bulging. My MESR-100 gives a 26 ohm reading on the bulging cap. (CapXon 47uF, 25V) So I will replace that and see if we are good to go. There are lots of other caps with the same brand/rating, but I think I will leave them for now.

All the other caps you highlighted tested good.
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Old 04-16-2017, 01:43 AM   #533
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Default Re: Dell 3008wfp faulty power supply

I'm pretty sure the one next to the Genesis Logic IC is also bulging, just not as much as the other. The reflection on only half the top gives it away.

Remember, if you're testing in-circuit, then the ESR meter can be fooled by good capacitors or other components in parallel...
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Last edited by Agent24; 04-16-2017 at 01:46 AM..
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Old 04-16-2017, 04:01 AM   #534
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Default Re: Dell 3008wfp faulty power supply

Great eyes Agent 24.

Yes I also replaced the cap next to Genisis chip. It tested OK but did have a slight bulge. I have tested all other caps of the same brand/rating and ESR indication is OK, with no visual bulging. I am now tempted to replace all caps of the same brand/rating, there is about 10 of them. What do you suggest?
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Old 04-16-2017, 06:03 AM   #535
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Default Re: Dell 3008wfp faulty power supply

I just did a quick re-assemble with 2 new caps and tried to turn on, but the symptoms have not changed. Blue power light is ON, black screen and buttons do nothing.

I have not re-measured voltages yet.

Any suggestions from here?
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Old 04-16-2017, 02:39 PM   #536
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Default Re: Dell 3008wfp faulty power supply

FtYou could try replacing all the same capacitors, or try heating the logic board with a hairdryer, then attempt power up. If there are any more bad capacitors, their ESR may drop low enough to let the board start.

Otherwise, I'd start going through all the regulators on the logic board. See if there are any which are getting an input but which aren't outputting anything (or the voltage is wrong). I can see quite a few of them. At least one will be powered from 5v Standby.

If you had a working board, you could dump/compare all the EEPROMs in case bad capacitors have caused corruption.

You could also check out the buttons themselves. Sometimes they can fail partially shorted and do all kinds of weird things.

Last edited by Agent24; 04-16-2017 at 02:42 PM..
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Old 06-09-2017, 09:34 PM   #537
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Default Re: Dell 3008wfp faulty power supply

Dead 3008 here as well - waiting for a replacement diode at the moment but this monitor has been a bugger to crack open compared to its smaller siblings.

1. the bezel was stuck on the left hand side. After attempting to remove it and denting the fragile metal skin in several places, the easiest way is to find where the clips are, slide a credit card into (on the outer side of the bezel gap) and downwards into the clip to unlock it. Hint - in general to remove the bezal the safest way is to use your fingers to pry open the bezel on the LCD side and simple pop off the front bezel. This avoids damaging the bezel.
2 The CFL driver cage was somehow caught in the rear of the case, requiring removal of the plastic surround from the rear cover (screws all round the perimeter. Even then I ended deforming the cage which required some just acceptable metalwork.
3. And the the 2 screws holding down the offending cage would not come off. Stripped the heads which required a screw extractor and more work.
3. Unlike the accepted practice of removing all the heatsinks from the psu, it is possible to undo the bolt holding down the offending D22 with a thin shaft driver and a pair of needlenose pliers, after which it was a simple matter of desoldering the diode and popping it out, taking care not to damage the heatsink insulator. The diode tested open on all pins so looks like the cause of the failure.

Last edited by rocket; 06-09-2017 at 09:38 PM..
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Old 06-10-2017, 03:33 AM   #538
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Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by rocket View Post
The diode tested open on all pins so looks like the cause of the failure.
Sorry meant to say all pins were shorted.
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Old 06-15-2017, 10:34 PM   #539
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Default Re: Dell 3008wfp faulty power supply

And chalk up another successful D22 replacement here!
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Old 09-14-2017, 06:45 AM   #540
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Default Re: Dell 3008wfp faulty power supply

Hi, sorry if this is a bit of a long post but I'm having a problem with my 3008wfp.

I replaced the D22 over 3 years ago now and that's still going strong however a few months afterwards I started to notice a single yellow line going down the screen.
The line goes away when the monitor has warmed up so I pretty much ignored it until a couple of months ago.

I opened it up to try to fix the line (thought it might be a capacitor or tab bond) and to add a fan to get rid of some of the heat these things produce.

I noticed a bulging cap on the logic board so replaced that and another identical one nearby (not yet bulging) with Panasonic FMís. The offending caps are the exact same ones shown in post 533 above.

The insulation on the LVDS cable was also crumbling away (although not as bad as some other cases on here) so I put heat shrink over each of the wires. While doing this I managed to break the end off one of the pins that goes into the LVDS connector. I butchered an Ethernet port from a motherboard and soldered part of one of the contacts onto the end of the pin. It wasnít perfect but seemed to be about the right size. I also twisted the same pairs of wires back together as they were before repairing the cable.

When I re-assembled and powered on the monitor there was huge amounts of display corruption, horizontal and vertical lines everywhere, whole screen would flash (yellow I think) and some pixels had a TV static effect to them where individual pixels were blue or red. To add insult to injury the yellow line was still there.
What I donít get is that it got better over time. After 1-2 minutes the lines and flashing stopped and after about 5 minutes the static effect went away. It would all come back upon switching input source, powering the monitor off/on or unplugging and re-plugging the DVI cable.

I left it for a couple of months and had another look at it earlier this week. I added shielding to the LVDS cable and also bought a new one (from a different monitor) and replaced the wire I broke a pin on. I also cleaned that connector as well as the ones on the ribbons that go from the TCON board to the LCD.
When I first re-assembled it I thought it was fixed but it came back after a few minutes of cycling through input sources. The ďno input detectedĒ screen is blue instead of black as well as some horizontal + vertical flickering lines. Plugged in my laptop and the display corruption was much better than before but still there. Now itís all gone after 30 seconds Ė 1 minute. I didnít leave it on much longer than that because Iím not sure how much (if any) damage all this is doing to components in other parts of the monitor.

Another thing I noticed is that both ribbons going into the TCON board had a very small crinkle in them in the middle (I've never messed with them before so they must have been like it originally). I tried flattening them out but it doesn't seem to have helped.

I have attached some pictures of how the monitor is now and will try to get a video uploaded later.
Sorry for the essay, just trying to include as much detail as I can. Not sure if anyone has some ideas about what the problem might be but help would be appreciated.
Thanks
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