Dell 3008wfp faulty power supply

[jetadm123]

Re: Dell 3008wfp faulty power supply

I was under the impression that this thread was dedicated to information on repairing the Dell 3800wfp monitor with has a faulty power supply meaning it will not turn on. So when I say that it has failed again after being repaired, the mode of failure has not changed. The monitor will not power up. I apologise for my brevity.

Ross

Didn't mean to rag on you and you are correct in saying this thread is for info on the 3008wfp monitor. However, the problem with using one thread is that many users with the same monitor can have slightly different problems, which can cause the monitor not to turn on. Therefore, each new post by a new member is treated like a individual thread. So, it's important for each user requesting help to provide good photos and a detailed description of the symptoms.

[koaschten]

Re: Dell 3008wfp faulty power supply

Hey all, I posted here before, I now have the faulty 3008WFPt at home and for the first week it seemed fine. Today it's exihibiting backlight flickering after "warming up" to about 21°C room temperature plus about 5 hours of use.

Any suggestions before I take it apart?

More of a generic 3008WFP question, as the one I just got in from our CAD guy is not totally black/dead. (yet)

If you switch it on it in the morning it is fine, but showing a full screen flickering after being powered on and displaying an image for 1h+.

Observations:
- Top back bezel is warm to the point that it's unpleasent to touch.
- Issue only appears if on for an extended time (1h+).
- Blowing compressed canned air in the small air vents left and right of the connection area the issue is gone for about 10-15 minutes. (mains/usb connector)

So currently it's rather a thermic issue than a failed semiconductor?

[selldoor]

Re: Dell 3008wfp faulty power supply

Try reducing the brightness by 10% and see if it stays on longer. Then if you dont hear any ideas from anyone else, do what I said in my response to your initial post.

[koaschten]

Re: Dell 3008wfp faulty power supply

Woah selldoor, reducing the brightness made it flicker slower, like from 20-30Hz to less than once a second when going from 85 to 70. Are we on to something here?

edit: reducing brightness to 50 made it go away completely for now.

[fuus]

Re: Dell 3008wfp faulty power supply

Firstly, all the original capacitors on your board *should* be fine.

and this: http://au.element14.com/stmicroelect...70v/dp/1295332
is the replacement part you want. Assuming your problem is the same as ours!

[eviltobz]

Re: Dell 3008wfp faulty power supply

Just wanted to post a big thanks to all the guys who've figured out the cause of the problem and detailed how to go about fixing it. My beloved 3008 died a couple of weeks back, and with the help on here I was able to fix it. Cheers all

[Darryl]

Re: Dell 3008wfp faulty power supply

What a great forum thread! I hope my problem is fixed as easily as most other's here.

My 3008WFP is just out of warranty. It belongs to my employer, a university, but I am free to monkey with it.

The symptoms are very much like koaschten's. Here are the details:

After it "warms up" (30 min to 1 hour) the display flickers a bit. Then it goes to a black screen for a few seconds. This cycle repeats every 4 or 5 seconds when the input is DVI-1. Here are more clues:

1. When the screen goes black, the blue power indicator remains blue (i.e., the entire monitor doesn't lose power altogether.)

2. It appears to be undergoing a screen reset. If I start the menu up, just before the screen goes black, the menu is gone when the screen comes up a few seconds later (the menu time-out is set for a much greater duration).

3. When I hook the signal to DVI-2 input, the problem still occurs, but less frequently. The screen stays on for 30 seconds to a couple of minutes, starts flickering and goes dark for a few seconds. Rinse and repeat.

4. The problem occurs with different computers connected and using different screen resolutions.

5. Shining a flashlight on the darkened screen does not reveal the desktop image.

6. The problem seems to be slowly be getting worse.

7. Turning down the screen brightness to zero with DVI-2 input keep things working (for now). I occasionally see a brief flicker, but the screen doesn't go dark. Turning up the brightness "restores" the behavior in #3 above.

To me, this problem does not sound like the same problem that most other's have had, where (I think) the entire power supply dies (blue light extinguishes with the screen). But fuus's response seems to suggest otherwise.

Does this problem seem like it will be fixed by replacing D22?

[retiredcaps]

Re: Dell 3008wfp faulty power supply

Does this problem seem like it will be fixed by replacing D22?

We don't know until you open it up and take a look at it. It could be bad capacitors. You can easily test the diode.

[Lumberjack777]

Re: Dell 3008wfp faulty power supply

I just fixed 4 of these. In each case it WAS the D22 Schottky diode. And the blue power light never came on before it was repaired. So this could be anything. Bad capacitor. Maybe a faulty lamp (ccfl). We can help you fix it, but we'll need good pics, top and bottom of the PSU and the main board. Make sure to upload them using the "manage attachments" option.

[RGBNZ]

Re: Dell 3008wfp faulty power supply

Does this problem seem like it will be fixed by replacing D22?

I have found that my monitor is doing the same thing (although it happens just after turn on). After further discussion with its former owner I found it used to run for a while before dying, but the run time got less and less over time.

D22 had been replace before I got the monitor (and is still ok), so my first thought was backlight control. I have trace back and found that the whole backlight power supply is turned off when the monitor restarts.

I realise this does not help solve the problem, but I thought it doesn't hurt to mention it.

As far as I know it is easy to detect a faulty D22 in-circuit, so it is certainly the first thing to check, just not easy getting inside the dam monitor...

Ross

[cfp]

Re: Dell 3008wfp faulty power supply

I've been having what sounds like a different problem with my Dell 3008WFP. Any advice would be much appreciated.

The bottom quarter of my screen is filled with horizontal and/or vertical lines. When it is at its worse, the bottom quarter of the screen is a solid block of colour. At other times, the bottom quarter of the screen duplicates other quarters, or is just broken up into flickering vertical lines. Reducing the contrast on the screen to 0% seems to help it, as does keeping that quarter black when not absolutely necessary.

I haven't yet opened the monitor up, as I'm not sure I trust myself not to do further damage (and a 75% working monitor's better than a 0% working one). But if someone had had a similar problem in the past, and fixed it through replacing something, then I guess it would justify me venturing inside.

Which parts of the circuitry are divided up into quarters? I had previously assumed it was a processing chip that had failed, but maybe this assumption was wrong.

Thanks in advance,

Tom

[selldoor]

Re: Dell 3008wfp faulty power supply

I've been having what sounds like a different problem with my Dell 3008WFP. Any advice would be much appreciated.

The bottom quarter of my screen is filled with horizontal and/or vertical lines. When it is at its worse, the bottom quarter of the screen is a solid block of colour. At other times, the bottom quarter of the screen duplicates other quarters, or is just broken up into flickering vertical lines. Reducing the contrast on the screen to 0% seems to help it, as does keeping that quarter black when not absolutely necessary.

I haven't yet opened the monitor up, as I'm not sure I trust myself not to do further damage (and a 75% working monitor's better than a 0% working one). But if someone had had a similar problem in the past, and fixed it through replacing something, then I guess it would justify me venturing inside.
Which parts of the circuitry are divided up into quarters? I had previously assumed it was a processing chip that had failed, but maybe this assumption was wrong.

Thanks in advance,

Tom

Most known faults on this set are covered in this thread - it could be something like a cable is not connecting or something more drastic like a cable is disintegrating -see post 240.
Until you open it up (a challenge in itself) you will never know.

[roncaron]

Re: Dell 3008wfp faulty power supply

I managed to disassemble my Dell 3008wfp. The power supply circuit looked in very good order with all nichicon (125 degree celcius) capacitors looking healthy. I'll need to invest in an ESR meter to check further.

For future reference these are the steps that I followed to disassemble this monitor:

1. Disconnected the monitor from mains and PC and relocate it to a very well lit area.

2. Using a credit card with one edge sharpened, part the top of the bezel from the black center plastic divider.

3. Using a plastic tire lever tool (ones for removing bicycle tires) wedge it into the gap made by the credit card and lever the tool so the black plastic center divider rises. Push down on the bezel and hopefully you have unlatched the clip. If you are seeing metal clips then you are removing the wrong clips. The clips are plastic and clip into the center black plastic divider (dividing back panel and the front bezel). Several tire levers help. Be careful around the bezel buttons as there is no slack for the ribbon cable.

4. With the bezel un-clipped rise the top of the bezel up by 90 degrees so the three very small screws holding the bezel button card can be removed. Remove the button card and from the bezel and put the bezel away.

5. Remove the monitor from the stand - 4 torque screws.

6. Place the monitor flat on a table with the screen up.

7. Un-clip the back panel with the center divider still attached from the metal body of the monitor. The tire levers or screw driver will do.

8. Turn the monitor over so you are now looking at the exposed metal body. Pull off all the metal tape that is in the way (pretty much all of it).

9. Disconnect the ribbon cable from the plug (pull out the brown ends by levering them outwards with a very small screw driver). Place the ribbon cable with buttons on the end in a safe place away from where you are working.

10. Remove the single screw holding down the card reader. Slide the card reader from the slots holding it place.

11. Go to the opposite side now and remove the two screws holding down the cover on this side. Lift the cover up and out of the way.

12. Disconnect the plug that is now in view.

13. Remove the three small screws holding down the top metal cover.

14. Slide the cover out and place it out of the way.

15. Remove all screws holding down the main electronics plate (6 of).

16. Remove the 2 screws securing the 3-pin power inlet connector.

17. Slide the main electrical plate towards the card reader and lift the top end up so it exposes two cables plugged into the back of the display.

18. Remove tape and unplug these two connectors so that the main panel can now be lifted away and worked upon. The power supply board can now be removed once the 4 screws on the back of the metal panel and all screws holding the power supply PCB in place are removed.

19. Good luck.

IT WORKS !!!!

... thanks guys.

[preface]

Re: Dell 3008wfp faulty power supply

I fixed mine too by replacing the V30120S (Vishay) with stps60170ct (ST Microelectronics)

Seen that the V30120S shotky diode was internally shortcircuited as a precaution i also replaced the old 1000uF Capacitor serving the ex- V30120S Diode (D22?) with a dark blue BC Capacitor 1000uF 25v 125 celcius degrees.

Besides this also (re)applied new silicon thermal paste to the top of the short side of the 'T' which is screwed onto the sister sink before the heat transfers to the monitor chassis by means of pad.

20 minutes and counting. Will try to open all night if possible and will update this thread on stability.
40 minutes and counting (full brightness)

[Lumberjack777]

Re: Dell 3008wfp faulty power supply

I fixed mine too by replacing the V30120S (Vishay) with stps60170ct (ST Microelectronics)

Seen that the V30120S shotky diode was internally shortcircuited as a precaution i also replaced the old 1000uF Capacitor serving the ex- V30120S Diode (D22?) with a dark blue BC Capacitor 1000uF 25v 125 celcius degrees.

Besides this also (re)applied new silicon thermal paste to the top of the short side of the 'T' which is screwed onto the sister sink before the heat transfers to the monitor chassis by means of pad.

20 minutes and counting. Will try to open all night if possible and will update this thread on stability.
40 minutes and counting (full brightness)

Sounds good. Keep us informed please. Though I have never seen the newer schottky diode (D22) fail with the 170v reverse voltage. I have repaired 12 of these. The PSU is actually very good quality with 125c rated Nichicons. What you may want to do is check that mainboard when you have it disassembled. I found 2 bloated "crapson" caps on the first generation boards. One led to complete corruption of the eeprom that was not able to be repaired.

[fuus]

Re: Dell 3008wfp faulty power supply

I've ordered a new power supply board! Victory is imminent!

[selldoor]

Re: Dell 3008wfp faulty power supply

Hey thats great - where from? - nothing from the scottish chap then.

[fuus]

Re: Dell 3008wfp faulty power supply

The last available one from Taobao! Now to find someone more competent at soldering than myself and away we go!

[selldoor]

Re: Dell 3008wfp faulty power supply

Soldering? I thought the idea of buying a board was to save that.

[fuus]

Re: Dell 3008wfp faulty power supply

from what I gather the board I have purchased is used, therefore I assumed dead. If it comes with the D22 replaced then I shall be very happy indeed!