Samsung 2233SN panel problem

[senndogg]

hello. i got this "beautiful from the outside" monitor which tbh is diagnosted elsewhere and the other technician has described the panel as faulty. i can see the board, nothing faulty at a glance, but the display is out of focus, the contrast saturated and text nearly unreadable.
it is a Chunghwa CLAA215FA. ever spotted as faulty?

[momaka]

Re: Samsung 2233SN panel problem

Do the monitor menus/OSD have the same problem? If no, then this could be a video/logic board issue. If yes, it might be the t-con.

Either way, post some pictures of the video/logic board and the PSU board. I know this is unlikely to be power supply related issue, but if the voltages going to the video/logic board are unstable, you can get all sorts of weird behaviour. Could also be a marginal voltage regulator on the video/logic board.

[senndogg]

Re: Samsung 2233SN panel problem

thank you momaka, but i cant tell you if the OSD has this fault too because it is greyish itself, can tell the difference. i measured the voltages which are exactly:
the 16V rail : 15,73V
the 5.1V rail : 5,08V
the 3.3V rail : 3,23V
the caps look good and they are NXB Sam Young.

anyway these are some photos of the symptoms and the board.


By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29


the boards.


By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

By senndogg at 2011-12-29

[momaka]

Re: Samsung 2233SN panel problem

Try re-seating the LVDS cable that goes between the video/logic board and the t-con board.

The only other thing I can think of is if one of the rails on the t-con is going weak due to a ceramic cap becoming shorted. Post some pictures of the t-con, particularly around the area that has a round inductor. The t-con is likely located under a metal cover on top of the display.

[senndogg]

Re: Samsung 2233SN panel problem

ok, ill show you them asap.

[dpauto47]

Re: Samsung 2233SN panel problem

Also if you look at the diode on circuit # BD1 it looks like it is burnt out on the anode side of it. shown in pic image # 10

[senndogg]

Re: Samsung 2233SN panel problem

thank you dpauto47 but it doesnt seem like a diode to me. it has the resistor logo from the other side of the board and it measures approx 0 ohms.


here are the pics of the t-con:


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03


By senndogg at 2012-01-03

[Scenic]

Re: Samsung 2233SN panel problem

just to clarify what dpauto47 was talking about..

Also if you didn't notice yet (discussion in another thread), all those externally hosted inline pics scare some of the more knowledgeable people away, as most of them aren't really useful, but you have to wait for all of them to load and get automatically resized every time you open the thread.

Use the "manage attachments" thing if possible in the future.
Click "Go advanced" under the text box. Then on the new page, there's a "manage attachments" button below the text box. Use that to upload the pictures to the forum. Once that's done, you can close the little popup window and post as usual. The images will show up like below this post.

[senndogg]

Re: Samsung 2233SN panel problem

i totally agree to use this feature but i just thought that external links could be just a bit more handy (it has been required to me in most forums), but its ok. no prob for me.

that component DB1, which TBH i dont know what is it, i desoldered one leg , and measured with the diode tester, beeped at both ways, and had a resistance of 0 ohms. it has a resistor symbol in fact.

[trebo]

Re: Samsung 2233SN panel problem

that component DB1, which TBH i dont know what is it, i desoldered one leg , and measured with the diode tester, beeped at both ways, and had a resistance of 0 ohms. it has a resistor symbol in fact.

surely something wrong with it
looks like a diode
was wondering if it may be a ferrite bead???

[momaka]

Re: Samsung 2233SN panel problem

was wondering if it may be a ferrite bead???

Could be (and most likely is).

If there was problem with something on the primary of the PSU, the PSU (and thus the monitor) wouldn't have worked at all in the first place. So the problem most likely is either on the video/logic board or the t-con board.

I find the t-con easier to check, so let's start with that...

Using this picture as a reference
http://img249.*************/img249/6...1201031326.jpg
measure the voltage between the cathode side of D501 (the side with the white stripe) and ground. Place the negative probe of your multimeter on ground. A good ground point to use is usually the bare traces where the screw holes for the t-con are. Let me know what voltage you get. Ideally, it should be anywhere between 9 and 20V (depending on the t-con design).

Also, using this picture as a reference,
http://img821.*************/img821/3...1201031326.jpg
check the part number on IC502 and post it here (IC502 is the small black chip to the left of the round inductor).

[senndogg]

Re: Samsung 2233SN panel problem

Could be (and most likely is).

If there was problem with something on the primary of the PSU, the PSU (and thus the monitor) wouldn't have worked at all in the first place. So the problem most likely is either on the video/logic board or the t-con board.

yes. it looks that he hasnt got power issues. it just lacks quality of picture.

[senndogg]

Re: Samsung 2233SN panel problem

thank you very much momaka, im gonna test them soon.

[senndogg]

Re: Samsung 2233SN panel problem

the cathode side of the D501 and a good ground showed 13.08V
the IC502: AAT117
AOT256
0927

[momaka]

Re: Samsung 2233SN panel problem

the cathode side of the D501 and a good ground showed 13.08V

Looks good.

Next, measure the voltage at every pin of D502 and D504 with respect to ground.

the IC502: AAT117 AOT256 0927

Can't find a data sheet for it, unfortunately. It's not that important, though.

[senndogg]

Re: Samsung 2233SN panel problem

i think i screwed up sth. i just broke the connector of the t-con (( i think i cant resolder it cos the pins are broken


anyway here are the voltages

[momaka]

Re: Samsung 2233SN panel problem

i think i screwed up sth. i just broke the connector of the t-con (( i think i cant resolder it cos the pins are broken

Oops.
Keep it for spare parts. If you ever get a monitor with a white screen problem, you can use this one for parts. Or if you find a broken screen with a good LVDS connector, you may be able to put that one on this monitor.

anyway here are the voltages

These voltages look good too.
There's a variable resistor on the board (to the left of IC502 in this picture). I'm not entirely sure what it does, but one of my guesses is it could be for the gamma adjustment.
If you get the LVDS connector fixed, it may be worth to try and mess with this varistor to see what it does.

[senndogg]

Re: Samsung 2233SN panel problem

too many thanks momaka for everything, but i think i really broke it. im gonna try to resolder it when i ll have more free time. thanx anyway.

[hexid]

Re: Samsung 2233SN panel problem

HI Guys i have the same problem with this monitor ? Did you finde out how to fix it ?

[senndogg]

Re: Samsung 2233SN panel problem

hi hexid and sorry for the late reply.
my monitor is archived at my store as faulty and i have never managed to repair it again. i have kept it for spare parts. i have used its psu and ccfls for some purposes.
if you can go further with measurements we can try to help you.