Samsung 920NW 2 Seconds to Black

[selldoor]

Re: Samsung 920NW 2 Seconds to Black

Did you just try the test bulb on its own? try again using it to replace one original at a time.

Also - if your board is same as post1 ,set off (unplugged) for 5mins test the secondary resistances on the two inverter transformers - see attached pic Meter on ohms 2000 test S1 to S2 and S3 to S4
and post results

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

yes i used it just on its own, but will try it like you suggested, my boards the same but what i saw yesterday after checking voltages again, is that one rectifier/mosfet/transistor,cant really remember which is which, number d803, thos three legged ones with heatsink, the one reads 15v as it should according to spec sheet, other one reads 5v-6v and should also read 15v acording to its specs sheet, so looks like i neet to find a replacement?

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

I got results from test, i get about 626 on s1-2 and about 628 s3-4, i then connected the original lamps and the one test lamp like suggested, think i found the problem, a failing ccfl , with the one original disconnected and my test connected in its place the screen stays on but has a slight whining noise

[selldoor]

Re: Samsung 920NW 2 Seconds to Black

ok so transformer secondary windings are good. Perhaps the whining could be due to the test bulb being different size/resistance. I am busy right now but will read up on whining back lights. Perhaps others will chime in with ideas.

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

Thank you so far for the help

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

And yes the backlight is a bit smaller, came from a 17" square monitor if i recall correctly

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

What i also have noticed is that when the screen stays on with the test lamp, the backlights flicker a bit and then go steady or normal

[Rtech]

Re: Samsung 920NW 2 Seconds to Black

You have one that has failed, and also one that is very close to failing.

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

Thank you for the help so far, ill see tommorrow where i can buy ccfl tubes, or maybe salvage from another screen and see what it does then

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

Hi all just want to let you know i fixed the screen, yay, as i was stripping the lcd panel toe put in a different ccfl tube that didnt fit anyway and was a tiny bit short, i removed the old original tube which was faulty and as i looked at it, i sal on of the white small wires looked like it been burned or sumthing and upon closer inspection the white wire came loose, so opend it, resoldered and all is well again, oh and the slight humming noise seemed to go away or is just much more quieter

[selldoor]

Re: Samsung 920NW 2 Seconds to Black

That is good news - well done

[Phlox321]

Re: Samsung 920NW 2 Seconds to Black

Thank you all for your help, much appreciated .

[C152Heavy]

Re: Samsung 920NW 2 Seconds to Black

Add me to the list of 920 NW veterans, the thing would work fine (until it warmed up?) then 2 seconds.

Thanks to those who went before me and diagnosed this and posted up.

This evening I dismantled the guts of the panel, re-soldered the fine wires on one set of tubes and it's back up and running. Probably should have done both sets but it "burned in" fine on the bench with everything apart and twisting the backlight assemblies some to look for intermittents.

That's the deepest I've had to go into a monitor to get it back on its feet.

D