Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Computer Displays
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools
Old 03-15-2012, 11:42 AM   #21
jetadm123
Badcaps Veteran
 
Join Date: Feb 2010
City & State: California
Posts: 2,132
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by Jetset View Post
Ahhh...Yes, I can just about read the silk screen using a bench magnifier. The component is definitely D22!

One other question if I may: Do you know if this diode blowing is likely go have damaged anything further down the 14V line (I can't see any fuse or fusible link that would normally be present in a SMPS to protect against such failure, and I'm using the old mains plug from the UPS to power the new 3011, so nothing has blown externally)?

Thanks for your response.

Colin
Since no one on this thread has provided a photo on the entire power supply, it would be great for future reference if you could do so. Besides, without a photo it will be difficult to point things out to you, since I doubt other members will have memorized what the board looks like or have a similar board sitting in front of them in order to provide answers to your question.
jetadm123 is offline   Reply With Quote
Old 03-15-2012, 01:26 PM   #22
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

I will certainly do that, but it'll be the weekend before I can do it.
Jetset is offline   Reply With Quote
Old 03-17-2012, 09:36 AM   #23
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Images of back and top of Dell 3008WFP SMPS attached. I've had to resixe them to a size allowed by this site. I can take a 22Mp image if needed using my 5DMKII, but it would be 5-6Mb.

I'll upload another picture of the area of the board under the secondary side heatsink after I've removed it. I don't think I can get at the mounting screws of two other devices to undo them, so will have to desolder those as well to get the top heatsink plate off.

Colin
Attached Images
File Type: jpg Dell3008PSU-SolderSide.jpg (1.64 MB, 400 views)
File Type: jpg Dell3008PSU-ComponentSide.jpg (1.24 MB, 392 views)
Jetset is offline   Reply With Quote
Old 03-17-2012, 01:58 PM   #24
jetadm123
Badcaps Veteran
 
Join Date: Feb 2010
City & State: California
Posts: 2,132
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by Jetset View Post
Images of back and top of Dell 3008WFP SMPS attached. I've had to resixe them to a size allowed by this site. I can take a 22Mp image if needed using my 5DMKII, but it would be 5-6Mb.

I'll upload another picture of the area of the board under the secondary side heatsink after I've removed it. I don't think I can get at the mounting screws of two other devices to undo them, so will have to desolder those as well to get the top heatsink plate off.

Colin
Unfortunately, two-thirds of your board is covered by those two metal plates. Please retake the photo without them. One thing though, it's a really lousy design because those plates retain heat in the enclosure and cook the caps inside. With the exception of the large 450V cap, you might consider recapping the entire supply.
jetadm123 is offline   Reply With Quote
Old 03-17-2012, 03:42 PM   #25
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

When re-assembled, the two heatsinks are fixed to the external metal rear housing which totally encloses the PSU and logic board of the monitor, the secondary side using thermal compound, the primary using heat conductive pads. I'm sure the design intends that heat is dissipated by vertical airflow over the vertical rear housing as there are metal grills top and bottom of the enclosing plastic case.

I will remove however much of the secondary heatsink as needed to replace D22 and post another picture. Even that seems to need 2 additional 3 pin diodes removing as I can't seem to get at the mounting screws via the heatsink side opening. The same would be true for the primary side, so that won't be touched if the D22 diode fixes it on the secondary side.

All the capacitors are visually OK, but I'll only remove them to check ESR if I still have an ongoing problem (based on previous posts about D22 replacement being sufficient).

Does anyone have access to a circuit diagram of this board?

Thx

Colin

Last edited by Jetset; 03-17-2012 at 03:43 PM.. Reason: Fixed typo
Jetset is offline   Reply With Quote
Old 03-21-2012, 01:21 PM   #26
vogelkun
New Member
 
Join Date: Mar 2012
City & State: madrid
My Country: spain
I'm a: Knowledge Seeker
Posts: 2
Default Re: Dell 3008wfp faulty power supply

Hi, everyone! seems that I have the same problem here.
I was able to open the monitor and change the power supply for another one I found as a part... but after a bit of work it's not working again.

I'm assuming its also that diode, and I'm willing to change it (though my experience in this is almost zero) but can't find anywhere the "STPS30170CT" that Lumberjack777 used with success (170v instead the vishay 120v). That model is everywhere as obsolete or out of stock. He wrote that used this one:
http://search.digikey.com/scripts/Dk...5-ND&x=23&y=16

although the Current - Average Rectified (Io) (per Diode) is detailed as 15A and the Vishay is 30A? I do seem to find a 30A version of the 170v reverse voltage schottky...
All this I'm writing with no knowledge at all, so excuse me if I'm saying crazy stuff.
Anyway, my question would be, what diode should I get to try to change it? Seems like mine also blows after some use...
Thanks to everyone in advance.

dani

Also, I photographed the disassembling of this monitor, if anyone is interested in it I could upload it somewhere.
vogelkun is offline   Reply With Quote
Old 03-21-2012, 05:25 PM   #27
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Vogelkun,

I just fixed mine using a STPS40170CT device (40A and 170V reverse rating). As you're in Europe, you could purchase from RS Components (rswww.com)as I did. Part number is 624-7586.

A couple of notes for everyone repairing this particular monitor:-

1) It's actually the BACK plastic cover that you need to seperate from the front, although you'll have to slightly move the front bezel forward as the actual monitor (made by LG) is held in the rear cover by some plastic clips. There is less than an inch of 'free play' in the cable that attaches to the front panel, so be careful!

2) I mention this because I could initially only get the 'input source' switch to work when I powered up the repaired monitor (minus back cover), and thought I'd damaged the switch cable. However, it's just that the monitor NEEDS an input source connected before the rest of the buttons will work - strange but true as all the buttons worked after connecting it to my laptop via a VGA lead.

So, Now all seems to be working. I'm running a 'conditioning cycle' via the menu to give it some heat-soak before refitting the back cover.

Hope this helps you and others.

I will post pictures of the SMPS minus the secondary side heatsink back to my earlier post if I can, but they really don't add anything. Basically, you have to de-solder two additional diodes at the end of the heatsink, the two tags that attach the heatsink via TP holes, and two countersunk screws, so you can remove the top heatsink plate and get accesss to D22. D22 is retained by a nut and bolt using loctite and passing through an insulating central washer and insulating TO220 pad on each side of the vertical heatsink that remains after removing the top one (it mounts 'back to back' with another TO220 device).

Colin

Last edited by Jetset; 03-21-2012 at 05:33 PM.. Reason: Added additional info.
Jetset is offline   Reply With Quote
Old 03-21-2012, 06:17 PM   #28
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Doesn't appear I can update the post with the original pictures in, so here they are.

The first shows the points that have to be desoldered to remove the top heatsink plate.

The second show the position of D22.

Colin
Attached Images
File Type: jpg DEll3008PSU_Unsoldering_points.jpg (147.0 KB, 391 views)
File Type: jpg DEll3008PSU_Faulty_D22_Position.jpg (366.7 KB, 478 views)
Jetset is offline   Reply With Quote
Old 03-21-2012, 10:06 PM   #29
retiredcaps
Badcaps Veteran
 
Join Date: Apr 2010
City & State: Canada
Posts: 9,078
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by Jetset View Post
Doesn't appear I can update the post with the original pictures in, so here they are.
Click on edit, then go advanced.
__________________
--- begin sig file ---

If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

Please do not post inline and offsite as they slow down the loading of pages.

--- end sig file ---
retiredcaps is offline   Reply With Quote
Old 03-21-2012, 10:10 PM   #30
rynson
New Member
 
Join Date: Mar 2012
City & State: ZAMBALES
My Country: phillippines
I'm a: Knowledge Seeker
Posts: 1
Default Re: Dell 3008wfp faulty power supply

what happen to your dell sir
rynson is offline   Reply With Quote
Old 03-22-2012, 04:34 AM   #31
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by retiredcaps View Post
Click on edit, then go advanced.
Ummm.... This board doesn't seem to allow that if subsequent posts have been made. The edit button only seems to appear if mine is the most recent post.
Jetset is offline   Reply With Quote
Old 03-22-2012, 04:40 AM   #32
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by rynson View Post
what happen to your dell sir
Total loss of power. The screen just went blank during use and the blue power light went off.

Fortunately, this forum and thread has given me the solution, replacing D22 on the PSU board.

I'm wondering if this is a reverse voltage or thermal degradation problem as the monitor worked fine for just over 3 years, albeit it ran much hotter than the replacement U3011.

I've ordered a couple of heatsinks to try (will mean cutting a 100mm square hole in the back plastic/metal cover and having the heatsink protruding, but I'm not happy with the current internal metal cover temperature of 50C in the relevant area without the plastic rear cover fitted.

Colin
Jetset is offline   Reply With Quote
Old 03-24-2012, 08:41 AM   #33
vogelkun
New Member
 
Join Date: Mar 2012
City & State: madrid
My Country: spain
I'm a: Knowledge Seeker
Posts: 2
Default Re: Dell 3008wfp faulty power supply

Thanks so much Jetset, just ordered the part!
Hopefully I can try to fix it next weeked, will keep you informed
My monitor also worked fine for almost 4 years... programmed obsolescence?
vogelkun is offline   Reply With Quote
Old 03-24-2012, 11:56 AM   #34
Jetset
New Member
 
Join Date: Mar 2012
City & State: Yeovil, Somerset
My Country: U.K.
I'm a: Knowledge Seeker
Posts: 10
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by vogelkun View Post
Thanks so much Jetset, just ordered the part!
Hopefully I can try to fix it next weeked, will keep you informed
My monitor also worked fine for almost 4 years... programmed obsolescence?
I'd agree with either programmed obsolescence, or just plain bad thermal design. There is negligible airflow over the metal back cover that acts as the ultimate heatsink. The U3011 has a slightly better grill arrangement, and runs much cooler.

Colin
Jetset is offline   Reply With Quote
Old 04-24-2012, 03:11 AM   #35
synatrol
New Member
 
Join Date: Apr 2012
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 13
Default Re: Dell 3008wfp faulty power supply

Hi all,

I seemed to have missed the era of bad caps - I was happily doing a lot of solo travelling from 2002 to 2007. In 2008 I bought this amazing monitor - the DELL 2008wfp. Four years on it is still working but I suspect an imminent demise to the power supply. It doesn't seem to be D22 as discussed in this thread as the monitor is still functioning. Here are the symptoms my monitor is displaying:

1. For a few weeks now the monitor's power supply has been making a whirring noise like a fan with shot bearings or a hard drive working hard. The noise disappears after 1-2 hrs of use.

2. The last few days has seen the display output (DP) switch off approximately 10 seconds after a cold power-up. The blue power light remains on. Turning the monitor on and off from the mains gets the monitor working again. This may happen a few times until
the monitor starts to warm up.

3. The monitor sometimes fails to enter hibernate mode after extended periods of being idle in which case upon waking the computer the monitor display is very blurred and looking very purple. Again turning the mains on and off gets the monitor going again with similar start-up issues as in symptom 2 above.

In summary the monitor seems to be functioning well when fully up-to-temperature but showing erratic behaviour when cold.

Are these symptoms possible bad capacitor behaviour? If so it is probably better to dismantle the monitor now and replace all suspect capacitors before further potential damage is incurred? Or should I be following the old adage - "If it ain't broke don't fix it".

I'd really appreciate some suggestions.

Thanks
James
synatrol is offline   Reply With Quote
Old 04-24-2012, 03:30 AM   #36
Jasgriff
Badcaps Veteran
 
Join Date: Feb 2012
City & State: England
My Country: UK
I'm a: Knowledge Seeker
Posts: 521
Default Re: Dell 3008wfp faulty power supply

Hi James,

Welcome to the forum.

I think that most people on here would think that the majority of monitors are worth fixing if you have a little time and patience.

Random issues can be caused by capacitors. Capacitors have a lifespan that is affected by a number of things including how hot they operate at. As they get warmer their values change which can cause you monitor to do all sorts of strange things.

To find out what's going on you will need to take it apart and give us some really clear pictures of the top and bottom of both board. You will need a multimeter and a soldering iron and have a little knowledge on how to solder.

If you look at my sig below Retiredcaps has an example of a good thread this will help is remotely guide you through what to do.
__________________
Fixed so far : 1 Home cinema system, 16 LCD Monitors, 4 LCD TV's

How to resize your pictures guide click HERE
Retiredcaps Ideal post example click HERE
Jasgriff is offline   Reply With Quote
Old 04-24-2012, 04:08 AM   #37
synatrol
New Member
 
Join Date: Apr 2012
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 13
Default Re: Dell 3008wfp faulty power supply

Thanks Jasgriff,

This monitor has always ran hotter than I had liked. To me it produces similar amounts of heat as you see with plasma TVs. I've got a 40W analogue soldering iron that I pull out on really rare occasions. I'm mainly dreading the removal of the back cover from the front bezel - lots of patience. ANZAC Day here in Australia tomorrow so I should find the time to concentrate on the feat.
synatrol is offline   Reply With Quote
Old 04-24-2012, 04:14 AM   #38
Jasgriff
Badcaps Veteran
 
Join Date: Feb 2012
City & State: England
My Country: UK
I'm a: Knowledge Seeker
Posts: 521
Default Re: Dell 3008wfp faulty power supply

The bezel on it will be quite tough ad Dell monitors seem to be made from strong plastic. Just work your way around the top bottom and sides a little at a time. Don't try and pull it off when you have half of it unclipped.

Youtube has a few clips that will guide you on this one.

Whats ANZAC day?
Jasgriff is offline   Reply With Quote
Old 04-24-2012, 05:28 AM   #39
synatrol
New Member
 
Join Date: Apr 2012
City & State: NSW
My Country: Australia
I'm a: Knowledge Seeker
Posts: 13
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by Jasgriff View Post
The bezel on it will be quite tough ad Dell monitors seem to be made from strong plastic. Just work your way around the top bottom and sides a little at a time. Don't try and pull it off when you have half of it unclipped.

Youtube has a few clips that will guide you on this one.

Whats ANZAC day?
A public holiday to remember sacrifices of military servicemen (Australian New Zealand Army Corps)
synatrol is offline   Reply With Quote
Old 04-24-2012, 06:14 PM   #40
retiredcaps
Badcaps Veteran
 
Join Date: Apr 2010
City & State: Canada
Posts: 9,078
Default Re: Dell 3008wfp faulty power supply

Quote:
Originally Posted by synatrol View Post
Are these symptoms possible bad capacitor behaviour? If so it is probably better to dismantle the monitor now and replace all suspect capacitors before further potential damage is incurred?
Your symptoms are classic signs of bad capacitors with high ESR (equivalent series resistance). As the lcd warms up, the temperature rises and the cap's ESR drops allowing the lcd to work. When cold, the cap's ESR is high (more resistance) and the lcd does not work.

You should replace the caps NOW as bad caps can cause other components to work harder than designed or outside their specifications which leads to premature failure.

See my standard cap answer (regulars may skip)

http://www.badcaps.net/forum/showpos...84&postcount=3
retiredcaps is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 04:23 PM.
Did you find this forum helpful?