Samsung B2330 LCD Repair Question

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vladtess

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Hello folks.

I need help fixing a nice LCD screen. It is a Samsung B2330HD.

So. When i turn it on and connect, it powers on for about a second and then turns off. I did a flashlight test and it came out to be a positive - i see my screen but no backlight!

I opened the monitor and looked at the power board. It doens't seem that capacitors are blown/broken since they are very good looking, just like new. Pics below.

So could it it be 800 volt ballast? or is it really capacitors??

Thanks!!

PICS are attached.
 

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The inverter is that yellow rectangular unit, with a yellow stripe on it. It looks totally fine, no signs of burning, smell, etc. Note that it does turn on for like 2 sec and then shits off. so I think ballast/inverter is fine. Now about the testing of the caps, i don't know. I have a multi-meter that I can use.
 
To test the caps you need an ESR meter. You said it works for 2 seconds and then shuts off, but you also said that the screen comes on but not the backlite, can you clarify?
 
Meaning, that once I turn it on, it turn on well. All good. But 2 sec later backlight shuts down; but, with flashlight, I still see the image of the screen. Meaning, for some reason LCD (back light ONLY) turns off, while all else works good. Thanks for dedicating your time.

Also ESRs seem to be pretty expensive, no something I can play with I unsoldered one of them, seems to hold a charge..
 
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Might be a sense coil on the inverter transformer(s). If the circuit can't detect voltage in it's range it'll shut it down, the fact that the backlight itself starts up at ALL suggestions it's a feedback issue from the backlight power supply. Mind how fine those wires are... Under anything less than 10X magnification you'll miss so much it's absurd.
 
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vladtess said:
Also ESRs seem to be pretty expensive, no something I can play with I unsoldered one of them, seems to hold a charge..
Click to expand...

You can get good ones fairly cheaply £70-80 or so.

You can only check them with an ESR meter, holding a charge is meaningless.

It could be a duff tube in the panel, or pretty well anything - the inverters shut down if any error is detected.
 
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