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Old 06-11-2019, 04:35 AM   #1
rattlesnake
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Question LG 23EA53 black screen after one second, it works after 5 minutes, high pitched sound

Hello people,

When I turn the monitor on I can see the image for a second, then the screen becomes all black.
If I let it sit there and wait about 5 minutes, then I turn it off and back on again, it works normally.
But there's a hissing sound all the time, very high pitched sound.

I've been using this monitor for about 5 years.

Due to all these signs I think this is a bad capacitor.

I attach pictures of the PCB with the capacitors so you can judge and advice me what to do. Does any capacitor look bulged? Only (and slightly) the 100v 33uF one.

Any help will be appreciated!

All the capacitors I've been able to identify:

1:
2DQJ
33
100

2:
3A
VZH
68
35V

3,4:
3A
100
16J
Attached Images
File Type: jpg 1ea53.jpg (1.74 MB, 19 views)
File Type: jpg 2ea53.jpg (1.11 MB, 18 views)
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Old 06-17-2019, 04:09 PM   #2
frica
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Default Re: LG 23EA53 black screen after one second, it works after 5 minutes, high pitched s

I am in agree with you that the capacitor of 100v is slighly bulged. But remember that often capacitors could be bad with no visible evidence (bad capacitance or ESR).
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Old 06-17-2019, 04:49 PM   #3
R_J
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Default Re: LG 23EA53 black screen after one second, it works after 5 minutes, high pitched s

The 33µf 100v, is the main filter for the led string voltage. It is likely bad, those little caps don't have much inside to make much of a bulge

Last edited by R_J; 06-17-2019 at 05:03 PM..
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Old 07-10-2019, 01:00 AM   #4
rattlesnake
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Question Re: LG 23EA53 black screen after one second, it works after 5 minutes, high pitched s

I replaced the 100v capacitor with a new one (it took a while to arrive).
It didn't make a difference. Actually, I ended up removing all caps to check them and all were in spec.
Put them back on, nothing changed except now I don't get the screen working for a single second.
There's this hissing noise, pretty intense.
I removed all caps and turned it on, the noise is still there.
I recorded it and amplified it, it's here:
https://vocaroo.com/i/s0J6krASxfBM
It has some kind of pulse/rhythm to it.
I really wonder where could it come from, what could cause it. What could be broken?

Could one of these components be the culprit? If not, what?

I attach high res pictures of the components.
I managed to identify some of them:

8839BMP-C
25008M
https://web.archive.org/web/20180826...le/APE8839.pdf
https://www.ti.com/lit/ds/symlink/drv8839.pdf
VOLTAGE REGULATOR (PROBABLY)

208022-TI-31A-P06564
NO IDEA

D478-BA262Z
MOSFET
https://cdn.datasheetspdf.com/pdf-do...conductors.pdf

W25X40CLSNIG - Flash ROM
https://pdf.datasheet.live/datasheet...5X40CLSNIG.pdf

TROQ - 14.3H007
CRISTAL

4R7
Signal transformer
https://www.digikey.dk/product-detai...4R7-ND/2777571

330
DKzC1
Probably signal transformer too.

PJ3049
BR210
Rectifier diode

Resistance

Some unidentified fuse?

I know very little about electronics, so please excuse my ignorance and any blatant error.
Further information about how to diagnose the problem would be very welcome.
Thank you for your help to get this monitor working again!
Attached Images
File Type: png D478-BA262Z.png (201.1 KB, 3 views)
File Type: png winbond.png (210.5 KB, 2 views)
File Type: png 8839BMP-C.png (1.02 MB, 1 views)
File Type: png 208022-TI-31A-P00504-2.png (415.0 KB, 0 views)
File Type: png 4R7-DK_AC.png (458.5 KB, 0 views)
File Type: png 330-DKzC1.png (317.4 KB, 0 views)
File Type: png PJ3049-BR210.png (247.1 KB, 0 views)
Attached Files
File Type: zip noise.zip (1.36 MB, 0 views)

Last edited by rattlesnake; 07-10-2019 at 01:02 AM..
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