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Old 05-04-2020, 02:50 PM   #7
Drith
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Join Date: Apr 2020
City & State: Chicago, IL
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Default Re: DELL U2311Hb (E162032 Vol 3) Goes Black After 2 Seconds

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 View Post
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 View Post
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.



Quote:
Originally Posted by MeinFreund View Post
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.
Attached Images
File Type: jpg IMG_9515.JPG (859.8 KB, 6 views)
File Type: jpg IMG_9519.JPG (1.35 MB, 5 views)
File Type: jpg voltages.JPG (194.7 KB, 47 views)

Last edited by Drith; 05-04-2020 at 02:52 PM..
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