Samsung Syncmaster 245B Black screen and blue Power LED

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Hi guys.

Sorry I am a bit late for this party but I need some help with my Samsung 245b!

Recently the monitor suffered the same problem the OP had reported. The blue light was coming on except there was nothing on the display. Occasionally the screen might flicker for a nano second but essentially nothing was coming through.

Any other time I would have perhaps given up and just purchased a new monitor but this is still a very good bit of kit and I frankly cannot afford a new monitor at the moment so fixing it seems worth a try.

I hate to confess whilst I have some skill with a soldering iron by expierience with electronics is a bit lacking but I am willing to try.

I have taken my monitor apart found my way to the same circuit board a lot of people are talking about in this thread. So my question is what now?

Here are some pictures of my circuit board.












If you look closely in the first few pictures something broke away from one of the caps I think. My finger lightly brushed it and something literally flaked away.

Any help or advice here would be greatly appreciated.

Thank you in advance

Richard

[jetadm123]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Did you try measuring the values of the 3 resistors mentioned on post #1 of this thread?

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

We are now trying that. What results are we looking for exactly? We are a bit new to this...

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

We have just noticed that the "stuff" (goo if you like) around those 3 resistors is slightly charred and cracked. Or at least darker than some of first pictures in this thread.

Does that mean anything?

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Actually I just realised my pictures are a bit useless. Here some better ones of the two problem areas. I think.





Much better.

[budm]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Oh yes, the three 68 Ohms resistors damaged by bad glue, check those 3 resistors. Remove all those brown and burnt up glue, it may have damged traces and component legs also, they are also conductive.
You can see more pictures here:
http://s807.photobucket.com/albums/y...msung%20245BW/

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Ok. Ill replace all 3 of those then. What about the other are that looks ropey, the second picture?

Also do the resistors need to be re-glued? What am I looking for in terms of replacement resistors?

Thanks again in advance.

[budm]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

No glue needed, check the other resistor with dark brown glue to see if its value nad its legs are not corroded and is still OK. You can get the MOX type resistors from DIGIKEY or Mouser. You should remove the resistors and Ohm them out first. You may have more problem beside damaged resistors.

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

We have just tested all 3 of those resistors and they read fine at .67

We have cleaned all the glue and gunk off.

The plot thickens...

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

The other resistor is reading at .47 (RP820).

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Right. I just put it all back together hoping that maybe it would work and it didn't. Same problem as before.

[budm]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

You mean 68 Ohms, not 0.67 Ohms

[macready29]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

You mean 68 Ohms, not 0.67 Ohms

Yes. sorry.

So, Should I replace those resistors anyway?

What else should I be testing?

[Toasty]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Brown glue causes damage to the circuit by resistance. It effectively causing a low(er) resistance path (short) between exposed component leads. It does this (deteriorates) when it is heated over time, as would be the case with those power resistors.

It does -not- cause physical damage to the components.

If all 3 are reading ~68Ω, the resistors are fine.

[budm]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

It does eat away copper traces. So far I fixed this three of this model, all of them has one open 68 Ohms resistor, these 68 Ohms are in series, the bad one the glue had eaten into the body of the resistor.

[bathuu]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Thank you mr. PlainBill.!
I changed CM802 (18n 630V with a 22n ) and it's working now!

Where did you source that special capacitor?

[jetadm123]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Where did you source that special capacitor?

Located by PlainBill:

http://www.digikey.com/product-searc...0-ND&x=10&y=12

[bathuu]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

Just fixed mine by replacing RB805. Multimeter was not reading any value on that resistor. Other two were reading fine around 68ohms. So did not need to get to CM802 capacitor. Thanks to all who contributed to the thread.

[dc42]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

I'm glad to have found this thread! My 245B failed suddenly with the same symptoms (screen is black but power light works). I removed the power board, checked the resistors - all 3 look good and measure 68 ohms - and there are no bulging capacitors. Then I removed CM802 and checked it on my meter. It reads about 170pF instead of 18nF. New capacitor on the way!

[budm]

Re: Samsung Syncmaster 245B Black screen and blue Power LED

By the way, here is the SCH.