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-   -   DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds (https://www.badcaps.net/forum/showthread.php?t=84069)

Drith 04-21-2020 11:36 PM

DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
4 Attachment(s)
Hello! I have a DELL U2311Hb monitor (mfg. May 2010) that will show a regular picture for 2 seconds and then go dark. The green power light stays lit but the screen is black and the menu buttons do not function. The power supply board says it is E162032 Vol 3. I looked at all the capacitors and they seem visibly fine.

I tried testing each of the radial capacitors with a regular multimeter's resistance meter set to around 20k. I watched signal build on them (some of them I had to turn up the measurement to 2000 because they'd slow down and get stuck). All of them eventually went to infinity except one: C765. It settled in the middle and even when I set my multimeter to diode it would not go to infinity.

My plan was to de-solder all the brown/black/green caps and buy new ones from Digi-Key to put on. Is there a better place to buy them from? One I found to replace C765 (220uf 25V) was this one. Does it look like a good choice?

Should I buy an ESR Meter, and if so which one? I saw this LCR-T4 Mega328 on eBay for $9. Is it any good for testing bad capacitors?

Any assistance would be most appreciated!

Drith 04-23-2020 01:13 PM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
I tested all the resistors, the fuse, and the transistor and they seem good.

Drith 04-24-2020 05:45 AM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
I removed C765 and tested it with the multimeter. Now that it's removed from the board, it seems to test properly and when I set to measure 20k Ohm the resistance gradually rises and then goes to infinity just as the other caps do.

The board has a dozen caps. Should I buy replacements for all of them and try that, or is the problem likely somewhere else given they seem to test fine and they don't look visibly damaged?

CapLeaker 04-30-2020 07:07 PM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
Could be anything, from bad solder joints, bad capacitors, transformer going bad, bad connection somewhere...
You can’t check the health of a capacitor, by charging it up with your DMM in ohms mode and watch it climb. Only because they “look” good, doesn’t mean that they are good either. If you want to check caps you have to invest into an LCR or ESR meter.

R_J 05-01-2020 06:32 PM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
Check the voltages on the plug to the main board and see if they remain when the moniitor blanks out. I would suspect one of the ccfl's has an issue, either bad/broken ccfl or broken ccfl lead.

You may have a bad ccfl in the panel, there are 4 ccfl's, 1,2,3,4 so unplug 2,3,4 and see if you get a flash of backlight from ccfl #1 (this may be fairly dim) If you do see a flash of the backlight, unplug 1,3,4 and try again with #2, trying each ccfl by itself should confirm they are working or not. In some cases the wire on the ccfl breaks and that is all that is wrong.

MeinFreund 05-03-2020 08:08 AM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
I know its a different DELL model, but it sounds similar to the problem described here:
https://www.badcaps.net/forum/showth...699#post663699

Drith 05-04-2020 02:50 PM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
3 Attachment(s)
Thank you all sincerely for the replies! To aid searching and such, the power board says it is 4H.14W02.AF0.

Quote:

Originally Posted by CapLeaker (Post 958626)
Could be anything, from bad solder joints, bad capacitors, transformer going bad, bad connection somewhere...
You can’t check the health of a capacitor, by charging it up with your DMM in ohms mode and watch it climb. Only because they “look” good, doesn’t mean that they are good either. If you want to check caps you have to invest into an LCR or ESR meter.

You make a good point that without narrowing it down, and without an obvious issue from visual inspection, the issue could be anywhere and so I should focus on narrowing down the issue. Is there a budget LCR/ESR meter you might be able to recommend? Is the LCR-T4 Mega328 sufficient?

Quote:

Originally Posted by R_J (Post 958856)
Check the voltages on the plug to the main board and see if they remain when the moniitor blanks out. I would suspect one of the ccfl's has an issue, either bad/broken ccfl or broken ccfl lead.

You may have a bad ccfl in the panel, there are 4 ccfl's, 1,2,3,4 so unplug 2,3,4 and see if you get a flash of backlight from ccfl #1 (this may be fairly dim) If you do see a flash of the backlight, unplug 1,3,4 and try again with #2, trying each ccfl by itself should confirm they are working or not. In some cases the wire on the ccfl breaks and that is all that is wrong.

I did the flashlight test and can see the silhouetted picture! However, now the monitor does not flicker on at all. The blue power led switch lights, the set stays black, but I can see a silhouette with the flashlight. Does that mean the issue is likely the CCFLs or the power supply going to the CCFLs, and so not the main board?

I tried disconnecting the four cables running to the panel leaving one plugged in at a time but it did not seem to have any effect. I could still see the silhouetted picture, but no backlight. I then tried having them all plugged in except one and it had no effect either.

I tested the voltages to the main board as follows. When the monitor is turned off, the 3rd pin that read 2.5 drops down to 0.02 and the fourth that read 0.65 drops to 0.12. The rest of the voltages stay the same whether the monitor is on or off.

https://www.badcaps.net/forum/attach...1&d=1588625373

Quote:

Originally Posted by MeinFreund (Post 959256)
I know its a different DELL model, but it sounds similar to the problem described here:
https://www.badcaps.net/forum/showth...699#post663699

I have checked over the threads and their monitor seems to be significantly different than mine. I don't see the transformer array or backlight tubes on mine, at least not in the same place. I attached full pictures of the monitor's guts.

Drith 05-18-2020 02:50 PM

Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds
 
What other tests or process can I go through to determine what is wrong? If it's the CCFLs that are burnt out, it looks like I could buy an LED replacement for pretty cheap but I'm not sure how to determine if that's the issue. Or if the power supply board is the issue, how can I check that?


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