Samsung 245BW power led comes on but no backlight

[bammbammfran]

Re: Samsung 245BW power led comes on but no backlight

Might be a glare in the picture, But on the cap you are testing in the one picture, it looks like you have the red lead on the negative side of the capacitor (Side with the line on it)
Black should be on that side.

You did not hurt the cap and I would stick to voltage checks before ripping caps out willy nilly

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

thanks for all that and yes i am a noob so i could be wrong about a great and many things but of this one thing i am sure: the resistor i was measuring is dead as a doornail. there is no corruption from my fingers (i figured that one out...my resistance is something like 1600k) i replaced that resistor and now i think i may have found the problem in the cm802 cap which is giving me only a 10 nf reading when it should be 18 .. im going to try replacing that first and if that doesnt fix it i will definitely remove and test the other caps.

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

so how do i go about ordering a new one of these?

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

is this the same thing? http://www.aliexpress.com/item-img/1...143960248.html

[budm]

Re: Samsung 245BW power led comes on but no backlight

High Frequency, Switching
http://www.digikey.com/product-detai...2121-ND/585188

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

thanks. ordered it. will let u all know what happens when it gets here

[C152Heavy]

Re: Samsung 245BW power led comes on but no backlight

Since we're talking about power supplies, electrolytics and reliability, here's an interesting read by Rockwell Automation:

https://cdn.badcaps-static.com/pdfs/...8bd945dc42.pdf

"MTBF ratings generally assume perfect manufacturing conditions and proper application of product - key factors that can drastically offset MTBF numbers. A better way to measure the MTBF of power supplies is to take a closer look at the electrolytic capacitors used in the product. Capacitors have a wear-out mechanism, meaning they generally have a limited life, and this can affect the power supply life span."

Interesting quote in the context that we're posting on "badcaps.net"

C152Heavy

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

thanks for all your help so far.
the capacitor came in the mail yesterday and i am going to put it in today
but then i realized its not like a normal capacitor that has a clearly marked negative and positive side. can i just put it in either way?

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

according to what i read, film capacitors and ceramic capacitors are not polarized and can go in either way. so i guess im alright then

[budm]

Re: Samsung 245BW power led comes on but no backlight

Yes.

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

oh man the 10 dollar soldering iron i bought from ebay http://www.ebay.com/itm/271481357228...%3AMEBIDX%3AIT
looks cool and is cheap and actually worked to do the soldering but im afraid it might be too cheap cause as soon as u turn it on, it starts melting itself, and smoke is coming out of the metal part..at the tip and at the base of the tube. what the???
i wonder if i should just turn it on outside and "let it burn itself out" ... or maybe ill take it apart and see what exactly is melting... *sigh* ebay....

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

oh and what is the alligator clip part for?

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

success! it turned out to be that 18nf cap! monitor works fine now! nice! THANK YOU!

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

dang this is a nice monitor! 1920 x 1200 24 inch!

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

just one small complaint though.. i see a faint ghosting effect on some things like 3 super light gray bars coming off to the right of anything with color...like for instance the thumbnail above should appear sharp but the right edge "bleeds" a little creating a kind of shadow of faint bars...
you can just barely make it out in the picture i took.
if you ignore the vertical lines which are a product of the camera trying to capture something that is refreshing, you can see that the image has a shadow to its right.

what could cause this effect, and am i calling it correctly "ghosting" or "shadowing" ?

its also happening in various other places of high contrast or certain colors...
not life threatening but still not perfect.

is this just a LCD screen problem, or could it be something crazy like capacitors almost but just not quite doing their job??

[budm]

Re: Samsung 245BW power led comes on but no backlight

Make sure all the connectors are seated, all the circuit board mounting screws are tight (a lot of boards are grounded through the mounting screws). It can also be bad filter caps on the main/scaler board.
Since you are working a lot now fixing stuff, it may be about time to get Capacitance meter, ESR meter.

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

yes i have the pieces for the ESR meter and now they gave me the instructions how to put it together so ill try to do that tonight. how necessary is it to get an oscilloscope?

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

today it seems like the mirroring/ghosting/shadowing effect is getting a little worse...

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

this is awesome. i bought a kit on ebay for 15 bucks, did a little soldering, and now i have a ESR meter.. well it tests a bunch of stuff...resistors, transistors, capacitance...

http://www.ebay.com/itm/281262386306...%3AMEBIDX%3AIT


so uh.. now i can desolder all the caps from the mainboard and test them! what fun! if only there were another way...

[triplefour]

Re: Samsung 245BW power led comes on but no backlight

hah good thing i caught myself before doing any of that...it was just a problem with the vga connector on my computer. switched to DVI connection and its all good now!