Samsung 2693HM - Doesn't turn on (no standby)

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

The voltage on the big cap looks a bit low. If you have 230V AC at the wall plug, you should get closer to 325V DC on the big cap (though if you have only 220V AC, the voltage on the big cap should be closer to 310-311V DC.)

I can't say for sure, it happens that I did measured wall socket AC voltage before I tested the 'standby' voltage and big fat cap voltage, but I forgot the correct value. I 'think' it was 227v AC.

could you post some pictures of the main/logic board too? There will probably will be at least 2 voltage regulators there (usually 3.3V and 1.8V) that we'll need to check out.

I made some photos of the main/logic board. Please check the attached photos. First 8 images are 'fresh' and last 2 are from back in 2017 (just so we can compare them).

What I noticed and what I tried to 'catch' with my phone camera are those....(kinda) like.... 'flame drawings'. You know, like when you try to draw a 'flame'. I thought 'oh, my main board is burned completely. You'll notice also at the right edge that its not a clear 'white' line but 'dirty yellowish' one. I managed to clean that line with 99% Isoprophyl alcohol. There is also some (I think a guy who assembled/checked the monitor in factory marked it with a pen), 'sign' on the board. I managed to almost clean that as well. Also tried to clean those 'flames' markings and I think they can be 'removed too.

But anyway, I thought board is burned. Then I had an idea to try and check if I have some old photos from back in 2017 of the same board. And...to my surprise board had the same 'flame markings' like it has now. So now I don't know what to think, but you might have an idea what those 'flame markings' mean?

Hi!

Yeah, I'm back. Actually, I never left this place to begin with. With all the nice knowledgeable folks around here, it's hard to do that.

You being one of them.

I actually like it when I see people asking a lot of questions - that means they are actively thinking about the problem, which is good.

Well, I'm glad that you like when you see many questions, but I know that many people don't like it. Just few minutes ago, I got 'slammed' for asking a long question from one guy (at an electronics discord channel) who told me: "write SHORT description of the issue. NOT a long story."

It's not that I like to 'bother' people with my long posts. I just try to provide (from my newbie point of view) all the information that I can. Maybe a value of the information that I provide is very small (or nonexistent) but I still like to provide it nonetheless. From my point of view, it can still 'create an image' of the situation and how I got there.

With good thorough responses, it's also easier for us to figure out what's going on. If anything, I think a lot of other fellow members here will agree that vague topics with vague questions about a problem or not reporting back (and then worse - ignoring or skipping over any suggested advice) tend to waste a lot more time to get to a solution and actually make it harder for us too.

I agree with you. I'm aware that I don't have a knowledge and I know (feel) that I'm at the right place to get directions. I understand that there is a present danger while checking components under high voltage. Thats why I ask so many questions. In electronics you can fix almost everything by changing it for a new part. But I got a no 'spare' life. So I gotta ask many questions.

[momaka]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Ok, here are the values that R_J asked me to check:

Standby voltage: 5.2v
BIG FAT capacitor voltage: 307v

The voltage on the big cap looks a bit low. If you have 230V AC at the wall plug, you should get closer to 325V DC on the big cap (though if you have only 220V AC, the voltage on the big cap should be closer to 310-311V DC.)

But I don't think that's the issue here, though. The main point is that you have 5V on the standby rail. This means the monitor's standby LED should at least be showing something and On/Off button responding.

Since you don't seem to be getting that, could you post some pictures of the main/logic board too? There will probably will be at least 2 voltage regulators there (usually 3.3V and 1.8V) that we'll need to check out.

I received an email notification that my topic has a new post. I checked it, and... OMG, it's him. He is back!

Hello momaka!

Hi!

Yeah, I'm back. Actually, I never left this place to begin with. With all the nice knowledgeable folks around here, it's hard to do that.

Where do you find patience to deal with so many questions that I ask, and in a way like you just did? You were doing the same thing 3 years ago when I had trouble with caps (for the same monitor). For every single question, I received an answer from you. I'm speachless. Thank you!

I actually like it when I see people asking a lot of questions - that means they are actively thinking about the problem, which is good. And it's even better when people respond back to our questions / instructions with thorough responses. After all, we don't have your device in front of us, so we rely on you to report back all observations. With good thorough responses, it's also easier for us to figure out what's going on. If anything, I think a lot of other fellow members here will agree that vague topics with vague questions about a problem or not reporting back (and then worse - ignoring or skipping over any suggested advice) tend to waste a lot more time to get to a solution and actually make it harder for us too.

That aside, while I do try to be thorough in answering questions, I'm not on badcaps everyday, so I can't help on as many threads. But members like budm, R_J, PeteS, stj, Per Hansson, petehall347, piernov and many many others who are here every day and offer so much help to everyone are truly the heroes.

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Ok, here are the values that R_J asked me to check:

Standby voltage: 5.2v
BIG FAT capacitor voltage: 307v

I also pulled 2 ceramic fuses out of the board, and resistance is 0.2 Ohm (on both). Same resistance (0.2 Ohm) is when two probes of my multimeter (black and red) are shorted. I guess it is nothing to care about, but fuses while in their board sockets, measured 2.7 Ohms 2 day ago. Probably the other board elements increased that value a bit, right?

Now, I don't know what are the markings that are written on the BIG FAT capacitor, because markings are on its other side which is not accessible.

User alfanikos had issue with his monitor (same monitor, same board model: BN44-00181B) and in his first post, his BIG FAT cap markings are hidden as well. But in the another post his picture shows a different capacitor and markings were (220uF 450v). Still, his measurement of that big fat capacitor was: 323v. So, I guess it's similar to a value that I measured (307v).

Here are his posts:
Samsung 2693HM. it operates and suddenly switches off (post #1)
Samsung 2693HM. it operates and suddenly switches off (post #10)


Can someone tell me if the values that I got indicate something, and suggest me what should be the next thing to check?

Thanks!

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

I received an email notification that my topic has a new post. I checked it, and... OMG, it's him. He is back!

Hello momaka!

Where do you find patience to deal with so many questions that I ask, and in a way like you just did? You were doing the same thing 3 years ago when I had trouble with caps (for the same monitor). For every single question, I received an answer from you. I'm speachless. Thank you!

I read your whole post. Right now it is 5.00 A.M here. I will re-read your post again and try to process all the information that you provided. Later I'll try to measure a standby pin voltage (if there is any) that R_J suggested me to check. And I'll report the results here.

Once again, thank you!

[momaka]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Q1:
First, I checked the connector from side point of view and he does have 16 pins. But when I was checking the soldered pins of that connector (on the bottom side of the board), I have to determ (and be sure) which one is the StandBy pin. I grouped pins and I hope I grouped them correctly (especially the StandBy pin). Can someone check that image, please?

That looks correct to me.

Q2:
There are also 2 other pins (not in the same line like the other 16 pins, positioned at the 2 far ends of connector). I would like to know what are these 2 pins.

Most likely, these are metal straps that go into the while plastic of the connector to make sure it is firmly attached to the board and can't be broken away easily.

Q3:
Another question is: when I put black probe on GND pin, can I stuck (lock) the negative (black) probe between two GND pins? IMO I can, but I would like to get confirmation on that.

Yes.
As long as you stick the probe between two pins with the same label (i.e. at the same potential, or lack thereof in the case of the GND pin), nothing wrong can happen.

Now if you do happen to slip your probe between two pins of different voltages, that may or may not cause damage to the monitor, depending on what voltages the pins are outputting and what their source is.

In the above case, you are working on the secondary side of the PSU, and these PSUs typically have pretty decent protection against short-circuit and over-load. So in the worse case, you may see a small spark if you short a voltage rail to ground, followed by the PSU shutting down gracefully (if it was working at all to begin with.)

Q4:
If (by accident) black probe touch one GND pin and red probe touch another GND pin, what would happen?

Nothing.

When you measure voltage with your multimeter, you can measure voltage between any two points and nothing bad will usually happen. Of course, there are some exceptions, like for example trying to measure voltage at the MOSFET output on the primary side - the high frequency and high voltage spikes from the inductive kickback of the transformer can kill some multimeters (usually the really dirt-cheap ones.) And it's not a good idea to measure the output of devices that are operating at high frequency - the probe wire length of your multimeter may cause undesirable effects in the circuit and break it. But no worries about this. We are not measuring anything like that here. I simply mentioned it for educational purposes. The above measurements at the connector on the secondary side are DC voltages and really nothing dangerous.

Q5:
If (by accident) black probe touch GND pin and red probe touch PWR ON/OFF pin, what would happen?

Nothing.

You might see a small stray voltage of a few mV...

Q6:
If (by accident) black probe toouch StandBy pin and red probe touch PWR ON/OFF pin, what would happen?

Probably nothing again.

Unless your meter has considerably low impedance on the DC voltage setting (extremely unlikely - most meters exhibit at least several MegaOhms impedance), chances are it won't be able to make the PSU try to turn On. (Because shorting or pulling high or pulling up the On/Off pin on LCD monitor PSUs to the Standby rail will tell the PSU's main supply to start running - i.e. the supply that runs the inverter/backlights, and whatever else that needs more power than just in standby mode.)

Q7:
I watched this youtube clip (I hope its allowed to post it):
...
And the guy sais that even if the board is powered with 120v you can't test it yet, because only one connector pin has voltage and thats PSON

Incorrect (well, I didn't watch the video, b/c I'm on a slow PC right now), but that statement above the way you worded it is not true.

First off, not all LCD TVs and monitors have a standby supply. Typically smaller monitors and TVs will have just a single always-On PSU that provides both standby and main power.

On bigger TVs and monitors that do actually have two power supplies on their PSU board (like your monitor above), there will always be standby supply that outputs some standby voltage on some connector that goes to the main/logic board. This voltage powers the logic board in stanby/soft off mode so that it can interpret when buttons are pressed on the monitor (in order to turn on, for example.) When the logic board sees that a button has been pressed, it can then send a signal (pull high or low, depending on PSU design) to the PS_ON pin to tell the main power supply to turn On (so you can get power to the backlights and everything else.)

I know this can be dangerous and I'm trying to collect all the information before I proceed. (I'm aware that its a simple proces for most of you, but...I'm a newb and I accept that I lack a knowledge, and thats why I'm trying NOT TO make any mistake.)

Most mistakes that people make are usually not related to measuring a voltage incorrectly, but rather how and where they are performing these tests.

First and foremost, JUST DON'T RUSH. Take your time and observe everything you do.

#2 mistake I see is people being messy (sometimes due to #1 above) and ultimately either dropping something on the board by mistake when it's powered On or not placing the board on a surface where it won't slip and/or fall and get damaged.

On that note, if your PSU board was installed in a metal box/case with the solder side pointing towards you (that's how many monitors are usually done), then you can install the PSU board back into that metal box so that the PCB will have less chance of slipping away when you try to measure it. Not to mention that once connected to the wall, the metal case of the box is at GROUND. So there's less chance of you touching something on the board and getting a shock or shorting out the power supply. And instead of holding the black multimeter probe to a ground pin, you can use the case as ground (provided the board tie-down screws are installed.)
Now if your PSU board doesn't mount in a metal case like that, then just place it on some kind of a NON-CONDUCTIVE surface. Even better if the surface has some friction to it, so the PCB won't slide around. And also, if possible, try to do it on a surface that is flame resistant... or at least not easily flammable (i.e. NO newspaper or regular paper.) Cardboard - passable, but don't leave anything connected unattended. A rough wood surface is one good example of surface that is non-conductive, has some friction to it, and is fairly flame and heat-resistant.

1. how exactly to measure the capacitor volgate while the power board is connected to power socket though power cable? Did the guys (from other place) told me correcty? Can the cap 'explode' when i touch its legs with multimeter wires?

No, nothing won't explode if you have your multimeter dialed in the right setting (in this case, DC Voltage and probes inserted in the correct slots on the multimeter - i.e. COM and V.)

2. Is the checking the big fat cap first, correct order of steps for trying to figureout what failed on my monitor power board (I would guess its the power board and no other kind of board like inverter, tcon, ...).

It's an OK first step.

However, not knowing how safe people know to be around high voltages, I usually advise with checking voltages on the secondary (low-voltage) side of the PSU, to determine if the PSU is indeed faulty or not. If that's not possible to determine (either due to PSU and/or device design) or inconclusive, then I advise to check fuses. And if that checks out OK, then do a measurement at the high-voltage cap on the primary side.

This is all for issues relating to "no power at all" from the device.

Anyone can help? I'm especially interested in SAFE steps about the 1st question No1. I know that I really need to be careful and to do things 100% correctly, so please advise me about that, so that I don't make mistake.

Besides the above advice I gave above regarding where/how to test the power supply, you may also want to use an extension cord with a power switch (if you have one) when performing the voltage tests on the PSU. That way, should something go wrong (typically the PSU shorting due to negligence or mistakes mentioned above), you should be able to shut down power to the PSU quicker this way.

btw. I did disassembled my monitor couple days ago. I tried to see if there anything 'melted' or 'damaged' on power board, but I didn't noticed anything. Some area of the board itself were...'darker', like...it was burned over a year because it was some heat there, more than on other part of the board. But it looked like (kinda) almost the same as it was back in 2017 when I was replacing the caps.

Yeah, a lot of older CCFL LCD monitors (i.e. before LED backlights became the norm) tend to run very hot and burn their PCBs like that.

In your case, the burn looks even worse, because the PCB is cheap phenolic type. The slightly more "expensive" fiberglass ones (typically yellow or white on one side instead of this orange / dark orange) don't burn up with heat like that.

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

The questions are not stupid, but don't slip with the probes, in this case it might not cause a problem, but when checking other parts of the circuit it could be fatal to the board.
Yes the yellow circled pin is the standby pin, you can place the ground on any of the 3 ground pins, or wedge it between two of them. You can just hold the ground probe on a ground pin and check for the standby voltage, you won't need to press power etc.

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Thanks R_J for trying to help me.

I'm asking these 'multitude' of questions because I NEED TO KNOW, before I proceed. I know you are a pro, and these qeustions might sound stuped from your point of view. But I'm a new to this, and I got no knowledge. So I have to know what to expect. I cannot allow myself to rush things, because with this kind of things, you make mistake only once.

So, can you check my 2nd picture and tell me: did I located StandBy pin correctly? (the one in yellow circle)

Also, on the last (4th) picture, can I 'stuck' black probe between 2 GND pins? I'm asking because it would be easier for me to 'hold' one probe in place while trying NOT TO 'slip' my red probe from the correct (standby) pin.

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

In the last picture, what is the voltage? You MUST HAVE THIS VOLTAGE.
The PSON pin is what turns on the rest of the power supply, without the standby voltage you will have nothing on PSON, so don't worry about it yet.
And for your multitude of questions, DON'T short out the pins
In picture 3, those other 2 pins are used to help mount/secure the connector

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Ok, I took the picture of that CNM803 connector.

So, can someone please check the attached images and see the questions that I have in my mind.

Q1:
First, I checked the connector from side point of view and he does have 16 pins. But when I was checking the soldered pins of that connector (on the bottom side of the board), I have to determ (and be sure) which one is the StandBy pin. I grouped pins and I hope I grouped them correctly (especially the StandBy pin). Can someone check that image, please?

Q2:
There are also 2 other pins (not in the same line like the other 16 pins, positioned at the 2 far ends of connector). I would like to know what are these 2 pins.

Q3:
Another question is: when I put black probe on GND pin, can I stuck (lock) the negative (black) probe between two GND pins? IMO I can, but I would like to get confirmation on that.

Q4:
If (by accident) black probe touch one GND pin and red probe touch another GND pin, what would happen?

Q5:
If (by accident) black probe touch GND pin and red probe touch PWR ON/OFF pin, what would happen?

Q6:
If (by accident) black probe toouch StandBy pin and red probe touch PWR ON/OFF pin, what would happen?


Q7:
I watched this youtube clip (I hope its allowed to post it):

How To Test LCD/LED TV Power Supply Boards (No Power)

And the guy sais that even if the board is powered with 120v you can't test it yet, because only one connector pin has voltage and thats PSON (on my board I believe its marked PWR ON/OFF). He also said that other pins wont have voltages until you short thtat PSON pin with StandBy pin (marked as '5v SB' pin in his case).
So... my question is: ...should I still expect to have 5v (or 3.3v) on StandBy pin even if I only connect the board to wall socket and then put black probe on GND and red probe on ST_BY pin, without shorting anything upfront?

Those questions are the ones that bothers me right now.I know it might be a lot of them, but I really need to know. I know this can be dangerous and I'm trying to collect all the information before I proceed. (I'm aware that its a simple proces for most of you, but...I'm a newb and I accept that I lack a knowledge, and thats why I'm trying NOT TO make any mistake.)

Thanks in advance for all your answers!

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

2.7Ω means the fuses are ok. the 2.7Ω is likely the lead resistance meter leads. If you short your meter leads together they will likely measure around 2.7Ω.

I checked resistance between red and black probes of my multimeter.
Resistance is only 0.2 Ohm.

btw. my multimeter is not a professional one, but I would like to think its good enough for this.
Model is ANENG AN8002 (I attached the image of it).

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

2.7Ω means the fuses are ok. the 2.7Ω is likely the lead resistance meter leads. If you short your meter leads together they will likely measure around 2.7Ω.
As for the voltage, all you need connected is the a/c mains supply, so be careful it can be dangerous.
Check if you have the standby voltage on CNM803?

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

I just checked all 3 fuses.

Red fuse has 2.7 Ohm

The other 2 (white) ceramic fuses also show 2.7 Ohm reisistance.


As for checking something under voltage, Im gonna need to make small steps with that, meaning I first need to be 100% sure what I'm doing before I actually decide to do it.

Also, thank you for trying to help me!

btw. Can you check the attached image, please? Is that where multimeter probes has to go while board is under voltage (connected though power cable to a wall socket)? I'm guessing you are reffering to that when you say 'white plug'.

ICB801 is the standby ic, in the pictures the ic's solder connections do not look that good, but it could just be the picture.

I think they look ok. My room light is strong, and because of that I had trouble to find the best angle while taking the pictures of the board.

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

No resistance is always measured without power applied. Most meters will "beep" in continuity mode with a resistance between 0Ω and 150Ω.
Re check the voltages on the white plug and see if you have any voltage on ST_BY pin. This is the standby voltage and is needed before anything else will work.
ICB801 is the standby ic, in the pictures the ic's solder connections do not look that good, but it could just be the picture.

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

OK, I'm a newb so my conclusions are probably wrong.

I hope you wont mind my next question (which might be a stupid one but... I gotta ask):

Since you ask for fuse resistance, does that mean that in order to measure it, the board has to be under voltage (connected through a cable to a wall socket). Correct?

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Yes, all 3 fuses (including a red fuse) beeps while checking them in continuity mode.

It beeps? beeps mean nothing, what is the resistance reading?

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

If you don't have standby, did you check the red fuse near ic801?

Yes, all 3 fuses (including a red fuse) beeps while checking them in continuity mode.

[R_J]

Re: Samsung 2693HM - Doesn't turn on (no standby)

If you don't have standby, did you check the red fuse near icb801?

[twist3r]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Hello guys. Thanks for your respond!

I finally disassembled my monitor again and made some pictures. I did checked some components (while board is NOT under voltage) and you can read what I noticed if you zoom in the images that I'm going to attach.

Can you post straight shot, high res pictures from all the boards front and back, then attach it using the attachment function? Maybe we can zoom in and see something? After all, if it smelled like burnet electronics, maybe we can find the problem.

I was thinking and.... one thought got on my mind. ....'Maybe' the smell I felt was comming from cable device (Set Top Box) itself. I'm not sure anymore. The only thing thats 100% true, is that my monitor doesn't work anymore.

The cable company tech guys came 2 days ago to install a new Set Top Box. I told them 'your STB device made me 'problem' . They instantly responded 'what problem, did it killed TV?' I said 'not a tv, but a monitor'. And they said 'yeaa, it sent hight voltage over HDMI cable. We have such cases every day, and we install new boxed every single day where such thing happens'.

I second what CapLeaker asked, and also to affirm that yes, checking the main filter cap is the first step in troubleshooting power problems.
But it is not necessary if you do have secondary voltages present, but we do not know that yet.
That said if high voltage entered via the HDMI port it would be extremely unlikely that the power board has failed.
It is allot more likely that the main ASIC IC has been destroyed.
But I do not understand why they do not cover the repair themselves if that is the case?

Ok, thanks. So big cap is the first step. I didn't tested it yet. Got to gather a courage first cause I fear high voltages since they are dangerous. I did measure low voltage caps and they show no voltage. But for big cap, I have to 'prepare myself mentally. Sure this sounds 'silly' or 'funny' for you, but for me its a big deal. Mistake is not the option.

As for your thought that maybe IC chip is destroyed,... I don't know what to thing since I have no experience with these things. Is it 'better' if an IC is destroyed and nothing something else?

And to answer your question about why they don't cover the repair themselves,...well the reason lies in the fact that you live where you live, and I live where I live.

Btw. I made some element markings 'zoomed in' (ICs too) so you can check them. Also, notice that some part of the board is pretty dark compared to other areas. I know its from heat, but the difference between light and dark areas is not small.

Few other things (which you can also read from the attached images):

'5W R12K' ....is that 0.12 Ohm resistor? Cause when I measured it it showed 0.7 Ohm?

Also, one diode acting 'strange'. It measure 0.313 in diode mode. But when multimeter probes switch places, it start from 0.600 and keep increasing that, to like 1.000 then keep increasing to 2.000 and keep increasing...


Also there are 2 diodes close to eachother. When I measure one diode (in diode mode) it shows 0.220, but when probes switch places, it show 0.860. Its the same for other diode next to the first one.

Other diodes that I checked goes from 0.4** or 0.5**, so I would say (as a newb) thats ok (they show 0L when probes switch places)

Ok, here are the image attachments below. Please zoom them in. I did best I could with my phone camera while trying not to get much reflect from room light.

btw. here is a stupid question: Can I use some (I think its called) ceramic resistor to discarge a capacitor like that big fat one? AND, should I expect some sparks or things like that? I bought one resistor like that a year or two ago, but I have to find where I put it (since I never used it).

[Per Hansson]

Re: Samsung 2693HM - Doesn't turn on (no standby)

I second what CapLeaker asked, and also to affirm that yes, checking the main filter cap is the first step in troubleshooting power problems.
But it is not necessary if you do have secondary voltages present, but we do not know that yet.
That said if high voltage entered via the HDMI port it would be extremely unlikely that the power board has failed.
It is allot more likely that the main ASIC IC has been destroyed.
But I do not understand why they do not cover the repair themselves if that is the case?

[CapLeaker]

Re: Samsung 2693HM - Doesn't turn on (no standby)

Can you post straight shot, high res pictures from all the boards front and back, then attach it using the attachment function? Maybe we can zoom in and see something? After all, if it smelled like burnet electronics, maybe we can find the problem.