Samsung SyncMaster 2493HM black screen with power

[superphreak4]

Re: Samsung SyncMaster 2493HM black screen with power

I've decided to try replacing all my caps. I purchased a kit for the Power Supply board but someone also mentioned replacing the 2 yellow caps on the inverter board, marked NXH 470uf 35V, in picture 5. Looking at the badcaps store and digikey, I realized I don't know exactly what I'm looking for. Digikey has so many fields to filter by.

What I do know I need:
Panasonic, Nichicon, Rubycon (recommended)
470uf
35v (or higher if no 35v ??)
105C operating temperature

What other requirements are there?

[PlainBill]

Re: Samsung SyncMaster 2493HM black screen with power

I am having the same issues as thirdoff. My 2493hm will just go black. The Blue LED is on solid. I can't see anything shining a flashlight on it. I also get the clicking/ticking noise. I have opened it up and the caps are not visibly swollen or leaking.

I don't have a multimeter, nor do I think I have the patience/understanding to run all the tests that may be suggested. I was wondering if I should still try replacing the caps?

Background: The monitor started doing it about a week and a half ago. The amount of time between failures progressively shortened. At one point it would work for about 2 minutes, about 30 minutes later it would only work for about 20-30 seconds. I replaced the monitor with an older one for a week and then connected it again because I forgot to do the flashlight test. The monitor didn't fail for another 2 days of non-continuous use.

If you don't have a DMM and don't have any patience, you have two options: Replace all the electrolytic caps, or sell it as non-working. The symptoms COULD be caused by bad caps.

PlainBill

[superphreak4]

Re: Samsung SyncMaster 2493HM black screen with power

I am having the same issues as thirdoff. My 2493hm will just go black. The Blue LED is on solid. I can't see anything shining a flashlight on it. I also get the clicking/ticking noise. I have opened it up and the caps are not visibly swollen or leaking.

I don't have a multimeter, nor do I think I have the patience/understanding to run all the tests that may be suggested. I was wondering if I should still try replacing the caps?

Background: The monitor started doing it about a week and a half ago. The amount of time between failures progressively shortened. At one point it would work for about 2 minutes, about 30 minutes later it would only work for about 20-30 seconds. I replaced the monitor with an older one for a week and then connected it again because I forgot to do the flashlight test. The monitor didn't fail for another 2 days of non-continuous use.

[mikepp]

Re: Samsung SyncMaster 2493HM black screen with power

Thirdoff, I await the results of your testing as my same monitor is doing exactly what yours is. If there are this many same problems with this monitor wonder why Samsung doesnt do a recall or at least suggest a fix.

[jetadm123]

Re: Samsung SyncMaster 2493HM black screen with power

Sorry for hijacking your thread. But since my problem was "Samsung SyncMaster 2493HM black screen with power" it looked ok to be here since other users that may have a "Samsung SyncMaster 2493HM black screen with power" would find it here. Even you could benefit from that.
Best. Glad your mon is working.

On this forum, it's okay to attach your monitor to an existing thread as long it's the same model for the reason you explained. It can add some confusion if you have multiple members trying to post their monitors around the same time and can extend the thread over many pages, but by keeping everything in one thread, it reduces the number of threads for the same model monitor.

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

Sorry for hijacking your thread. But since my problem was "Samsung SyncMaster 2493HM black screen with power" it looked ok to be here since other users that may have a "Samsung SyncMaster 2493HM black screen with power" would find it here. Even you could benefit from that.
Best. Glad your mon is working.

[thirdoff]

Re: Samsung SyncMaster 2493HM black screen with power

I should be getting back to this soon, the monitor has been working since my last post. It has worked for this long before so I suspect it goes back out. If/when it quits again I will continue to test as needed and post my results. I would request the moderator clip this thread at it's hijacked point and start those posts a new thread as it is VERY OFF TOPIC and the original info could really help someone else. The barbas posts are not related and do NOT contribute to this topic. Thank you.

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

Now the ON/OFF rail that should be more than 2.4VDC is 2.8VDC. Also the value in the A-DIM rail increased to 1.3VDC. Seems healthy huh? I think I was right into assuming that these fuses do open over time, in a slow fashion. Obviously one would think it would be better to replace it with one of the same kind, that I would do eventually.

Some funky stuff appeared on the screen, that I do not know where it came. If someone has an idea, please share. See the attached pic:

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

An image is worth a thousand words, here are the results. I bypassed the fuse with a piece of wire and this was the result:

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

Hm also found this 3A pico fuse its putting 117ohm.

The specs from LittelFuse are here:
https://cdn.badcaps-static.com/pdfs/...255b0c9470.pdf

From the description:
"The NANO2 Slo-Blo® fuse has enhanced inrush withstand
characteristics over the NANO2 Fast-Acting fuse. The
unique time delay feature of this fuse design helps solve
the problem of nuisance “opening” by accommodating
inrush currents that normally cause a fast-acting fuse to
open."

That looks like a regular fuse would open easily, if not, why then they used that kind of fuse there? The one in the inverter is way different.
It states at the rated current (3A) it would take 4 hours to fully open. That indicates that even under low current, the material is reacting and may be that is opening slowly over time, maybe years until you notice some resistance on it. As always, I could be wrong... But I believe any fuse would work there. It states its cold resistence would be 0.0340ohms. I think I am way over...

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

It seems like a lot of samsung boards use the same specs. I saw the picture of this one and is pretty much the same as mine. Here are some mfg specs:

1 24 V
2 24 V
3 24 V
4 24 V
5 24 V
6 GND
7 GND
8 GND
9 GND
10 GND
11 No Connection (DO NOT CONNECT) *ERROR DETECTION (NORMAL : GND / ABNORMAL : 5V)
12 Backlight On /Off [ON:2.4 – 5.25 V, OFF: 0 - 0.8 V]
13 Dimming Control [0V:Min, 3.3V:Max]
14 No Connection (DO NOT CONNECT)

I just tried to get better readings at the A-DIM and ON/OFF rails with the cheapo meter.
A-DIM:0.130VDC
ON/OFF:0.28VDC

Since I had the brightness from the controls set to very low, I am not suspecting from the A-DIM right now. But I will try to put a 5VDC lead on the ON/OFF rail to see what happens later this night.

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

Thanks for chiming in. Well, maybe I did not elaborate enough. The cap that I replaced from the power supply has been working fine since like 7 months, the monitor had problems to turn on its power led, and the cap was leaking. The inductor transformer broken solder making the arc; I fixed it like 9 months ago. Now yesterday it did not start all of a sudden, but its power led remained lit, so I am not suspecting of the PSU, also because of it putting the right amount of volts right in those rails.
Now talking about the power supp cap I replaced, I would not think of it being the best, its hard to find a shop with good caps here, I live far from US, and I need the monitor to work on it, so wait for a intl shipment is an ultimate choice. It is Jakec brand. There is a read in this forum where a person had success with them in a PSU.
My suspects are the logic board or the inductor board. The logic because of the "A-DIM" rail showing 0 volts, and the "ON/OFF" having low voltage, if the other read is an homolog, that could be it. However I do not have the skills to test it. Thanks for the kind help.

[PlainBill]

Re: Samsung SyncMaster 2493HM black screen with power

Hi. I am having blank screen problem with the same monitor. Had to replace a power supply cap recently, and now no screen. Also, I had an arc sound with a flickering from back light. Had to resolder one of those inductor things in the inverter board. If you turned the olights off you could even see the arc. Whats happening with the quality control from samsung?

I tested the voltage in the on/off line, my cheapo non exact multimeter read 0.28 volts on that line. The 24v rails all of them have power. The first and second (EX-PWM and A-DIM) read 0 volts.

Any word on this??? Could not see anything with a flashlight on the screen...

I am attaching some pics of the inverter board.

Let me post a hypothetical question. Assume you are about 12 years old and you go to your Mother and say "Mom, I was hungry a few hours ago so I ate something from the refrigerator. Now my stomach doesn't feel too good. But the cat was acting funny, so I took some pictures."

What do you think your mother's first question would be? Maybe "What did you eat?" And she probably wouldn't be impressed by the half dozen pictures you wanted to show her of the cat, either.

I'm not your Mother, but I WOULD like to know more about the cap you replaced. And is the power supply now producing the correct voltages? What's more, is the power supply getting the command to turn on the main supply?

PlainBill

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

This small reading could be of help here:
http://www.powerbookmedic.com/forum/...hp?f=13&t=2548

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

The arc was formed because of a broken solder spot.

I just read the A-DIM rail should be non zero. 0 means no light, 4V means light (not from this LCD panel, but may apply). Any words?

[Th3_uN1Qu3]

Re: Samsung SyncMaster 2493HM black screen with power

Well if you could see an arc i think it should be obvious that you need new inverter transformers.

[barbas]

Re: Samsung SyncMaster 2493HM black screen with power

Hi. I am having blank screen problem with the same monitor. Had to replace a power supply cap recently, and now no screen. Also, I had an arc sound with a flickering from back light. Had to resolder one of those inductor things in the inverter board. If you turned the olights off you could even see the arc. Whats happening with the quality control from samsung?

I tested the voltage in the on/off line, my cheapo non exact multimeter read 0.28 volts on that line. The 24v rails all of them have power. The first and second (EX-PWM and A-DIM) read 0 volts.

Any word on this??? Could not see anything with a flashlight on the screen...

I am attaching some pics of the inverter board.

[pumady]

Re: Samsung SyncMaster 2493HM black screen with power

Hi thirdoff, do you get the solution? My 2493HM monitor has the same problem, looking forward your suggestion.

[thirdoff]

Re: Samsung SyncMaster 2493HM black screen with power

Thank you, I still need to set it up so I can check the test points. I was not clear to where the "pins" were located on the inverter. On the white/blue cable or ???...
I was originally hoping just switching the caps would help. Does the noise reveal anything?

[alexanna]

Re: Samsung SyncMaster 2493HM black screen with power

Two seconds to black is just a very general term to describe a problem, it can be a lot quicker than two seconds. On some monitors you may not even be able to see through the dark LCD screen
Have you or can you verify that the backlight on voltage stays at about 3.3V when the lights go out?
PlainBill identified the pin to check.