Samsung SyncMaster 226BW

[Spood]

Re: Samsung SyncMaster 226BW

Successfully fixed my monitor thanks to the advice in this thread after coming across it with a google search, my thanks to all!

[EGuevarae]

Re: Samsung SyncMaster 226BW

Successfully fixed my monitor thanks to the advice in this thread after coming across it with a google search, my thanks to all!

For the record, please post info on the symptoms and what did you do to the unit to get it fixed.
And welcome ..!!!

[Spood]

Re: Samsung SyncMaster 226BW

For the record, please post info on the symptoms and what did you do to the unit to get it fixed.
And welcome ..!!!

Yessir.

First symptom was high pitch beep every time the blue light came on in standby mode (as it flashed), secondly monitor took increasingly longer to turn on when returning from stanby/turned off, accompanied by a 'struggling' high pitch beep. From a combination of this and my limited electronics knowledge I googled for 'syncmaster 226bw capacitor', and came upon this most useful of threads.

Took the monitor apart and noticed a bunch of hot sexy engorged capacitors, in a layout akin to Krickster's.

Using the list of caps from Toasty's post I set about ordering replacement capacitors from https://uk.rs-online.com/web/

Replaced all caps except the biggest one (you know, that fat bastard in the middle), plugged it in and turned it on, whereupon I was greeting with an extremely dim and flickering image. 'Ah', thought I, and subsequently shit myself. After regaining my composure I took the monitor apart again, crying into the night sky 'ONCE MORE UNTO THE BREACH DEAR FRIENDS, ONCE MORE'. It was at this point I realised the diddly little bastard capacitor up there at the top of the board was inserted upside down and at a rather jaunty angle.

After replacing this cap for the second time I slipped the power lead into the gaping maw of the monitor, ignoring its whorish protestations.

Defeated, the monitor once again worked. I then went to the pub and got drunk then replied to this post.

The end.

[Space Ghost]

Re: Samsung SyncMaster 226BW

I have the same (or very similar) problem with one of my Samsung SyncMaster 226BW monitors (I have two running side by side in a dual-head configuration). A few weeks ago the monitor (on the right) started blinking rapidly when coming out of sleep mode... eventually, after about 1 minute it would slowly stop blinking and self-correct. However, 1 minute became 2 mintes... and 2 minutes became 3 minutes... etc.

Eventually I discovered that if I turned down the brightness on the monitor while the screen was blinking, the blinking would stop when I dialed the brightness down into the 20s or so (out of a maximum brightness value of 100). Then, when the monitor would stop blinking, I would slowly crank up the brightness back to where I had it set (85). And the monitor would be fine and not start blinking again until coming out of sleep mode.

However, after a few days of doing this self-correction routine several times, I turned off the sleep settings entirely and kept the monitors on all the time (night and day). Of course I realize (now) that it probably only accelerated the problem. Today, the monitor starting blinking just in the middle of a computing session (not coming out of sleep). I turned the brightness down to 20 to get it to stop, but then this time the monitor started blinking again as soon as I increased it. Uh oh. After another few minutes of running at brightness level 20, the monitor started blinking again this time much more rapidly. I cranked the brightness down to zero (barely visible), yet the blinking did not subside. The screen kept blinking until it became completely dark... which is what it is now - dark black.

After a quick google search, I found this forum and have been reading the helpful posts from the many contributors to this thread. I did not know this until I cam here, but I discovered that this monitor has a 3 year warranty (thanks PlainBill!). I had no idea. So I quickly checked my invoice (which I still have). I bought both monitors from newegg on (wait for it).... April 30, 3007. 3 years and 1 month ago. Doh! The monitor was probably still under warranty when I first noticed the problem started. Oh, bother.

Out of desperation, I called up Samsung to see if I could sweet talk them into extending the warranty. Well, it turns out that if you "register" your product with Samsung, then you get an additional 3 months (total warranty time == 3 years and 3 months). So I hastily filled out the warranty card on-line at the suggestion of the helpful Samsung customer service rep and extended the warranty on the monitor by 3 months... which will now cover the return. Whew!

(Note: if you don't have the invoice for your monitor, Samsung customer service can look up your warranty information using your monitor's serial number. I asked about this explicitly.)

I got a return authorization ticket number and address shipping label to an authorized Samsung dealer not less than 15 minutes after hanging up the phone with Sumsung customer support. Wow. Had I not found this thread, I would have never realized I had such a lengthy warranty (3 years seems unheard of for electronic equipment!). I've bookmarked this thread in case my other (currently working) monitor decides to misbehave.

Many thanks to all the contributors!

cheers.

[tillwhompson]

Re: Samsung SyncMaster 226BW

First, I wanted to thank everyone who has posted on here... it's helped me along on the repair process of my monitor.

Unfortunately, it still has the same symptoms. I replaced all the capacitors (even the big one ) but it hasn't helped.

Symptoms:

Plug it in, power light comes on, it detects a signal, and then the back light flashes once and then stays off, however, the display is still active and can be seen if one shines a light on it. (It's faint, but there)

My guess is that it's a bad transformer or inverter controller, like PlainBill said.

What I've done so far:

Replaced all the capacitors on the PS Board.
Hooked up another identical LCD panel ( to the samsung unit) with the same result: (back light flashes, goes off, but the LCD is still getting a signal.)

Anyway, I was hoping someone could help me, or simply tell me how much trouble it will be to replace inverter controller or transformers, if that's really the problem.

Thanks!

[PlainBill]

Re: Samsung SyncMaster 226BW

First, I wanted to thank everyone who has posted on here... it's helped me along on the repair process of my monitor.

Unfortunately, it still has the same symptoms. I replaced all the capacitors (even the big one ) but it hasn't helped.

Symptoms:

Plug it in, power light comes on, it detects a signal, and then the back light flashes once and then stays off, however, the display is still active and can be seen if one shines a light on it. (It's faint, but there)

My guess is that it's a bad transformer or inverter controller, like PlainBill said.

What I've done so far:

Replaced all the capacitors on the PS Board.
Hooked up another identical LCD panel ( to the samsung unit) with the same result: (back light flashes, goes off, but the LCD is still getting a signal.)

Anyway, I was hoping someone could help me, or simply tell me how much trouble it will be to replace inverter controller or transformers, if that's really the problem.

Thanks!

Good job of troubleshooting. That eliminates the CCFLs and the wiring. It's unlikely the problem is the inverter controller. A transformer or the sense circuitry is much more likely. It's the old story, replacing the bad part is easy, it's locating it that is the problem.

Post 40 in this thread has a picture of the power supply / inverter. Compare it to yours. If it isn't an exact match I will need a picture of the front and back of yours. If it is an exact match, we're off to the races!

the first lap is quite easy. With an ohmmeter, measure the resistance between the two points on the left circled in yellow. Do the same for the two on the right. I would expect something around 1000 ohms, but we are looking for very small differences between them, so give the exact numbers, please.

PlainBill

[tillwhompson]

Re: Samsung SyncMaster 226BW

Thanks for your quick reply!

I took some time and compared the front and back of my board, and it looks like I have an identical board, (with the same OZ694GN chip also).

Results from measuring the resistance from the circled points with a digital multimeter:

Left points: 1101 OHMS
Right points: 1111 OHMS


So, there is definitely a difference between the two transformers Does this mean that one (or both) of the transformers are bad, and thus are tripping the sense circuitry?

[PlainBill]

Re: Samsung SyncMaster 226BW

Thanks for your quick reply!

I took some time and compared the front and back of my board, and it looks like I have an identical board, (with the same OZ694GN chip also).

Results from measuring the resistance from the circled points with a digital multimeter:

Left points: 1101 OHMS
Right points: 1111 OHMS


So, there is definitely a difference between the two transformers Does this mean that one (or both) of the transformers are bad, and thus are tripping the sense circuitry?

Aww, FUDGE!!! The answer is 'Maybe'. The resistance of a length of wire will vary slightly, a little extra tug, a slight change in composition in the copper can result in a change in resistance. A few shorted turns will make a small difference. As a first guess, I would say that a 1% difference is within normal tolerances. The only time I encountered a bad inverter transformer the variation was over 10%, and I had a bunch of them to compare. I just checked a known good pair and the variation was less than .5%.

Now the fun starts. The following exercise involves voltage and currents that could be painful, but probably not fatal. I STRONGLY suggest having an assistant, preferably not someone who stands to benefit financially from your demise. Hook up the monitor power supply / inverter and the LCD panel including CCFLs in such a manner that you have access to the bottom side of the power supply / inverter.

Notice on the picture I have identified 4 points V1-V4; these are the voltage sense lines for the inverter outputs. I have also identified 4 points as R1-R4; these are the current sense lines. Your mission, should you decide to accept it, is to measure the voltage on each of these points while the inverter is working. Use the large ground pad just right of the large black arrow in the center of the board as the ground point.

The suggested method is for one person to hold the probes and watch the meter while the other pushes the power button on the monitor, writes down the readings, and is prepared to call 911. The process would go like this: Plug in power, press power button to turn off monitor. Hold probes on test points, press power button, note the highest reading, when the CCFLs turn off press the power button again, repeat several times for each point. Obviously, we are looking for one point that is significantly different than the rest of that type.

PlainBill

[tillwhompson]

Re: Samsung SyncMaster 226BW

Oh, thanks for info! I always like learning about everything electronic! And I appreciate the somewhat humorous post

So, it looks like the transformers are okay.

Well, it looks like I have a problem:

Once I started measuring voltages... I could never get the same reading twice!!! I had HUGE variations in voltage every time.

Here are some of many, many measurements. I hand picked some of the highest values.

V1: 250mV
V2: 273mV
F1: 427mV
F2: 534mV

V3: 364mV
V4: 255mV
F3: 109mV
F4: 169mV

Now here's the kicker At one point during my hour of measuring seemingly random voltages, the lamps stayed on for about 6 seconds!!! Instead of the usual 1/2 second. I happened to be measuring V3 at the time and got a whopping ~660mV! Though I could never repeat that happening

For the most part, I got voltages around 100mV for most things. But the voltage definitely depended on how long I left the monitor off before another measurement. This is probably the most critical part of my findings, considering it renders all data useless

Another detail I noticed was that although I had been testing the monitor for quite a while, the surface on which I had the circuit board, never became warm... that probably is useless, but I figure the more details the better

So, I'm guessing this is not what you were expecting.... now what?

[PlainBill]

Re: Samsung SyncMaster 226BW

Oh, thanks for info! I always like learning about everything electronic! And I appreciate the somewhat humorous post

So, it looks like the transformers are okay.

Well, it looks like I have a problem:

Once I started measuring voltages... I could never get the same reading twice!!! I had HUGE variations in voltage every time.

Here are some of many, many measurements. I hand picked some of the highest values.

V1: 250mV
V2: 273mV
F1: 427mV
F2: 534mV

V3: 364mV
V4: 255mV
F3: 109mV
F4: 169mV

Now here's the kicker At one point during my hour of measuring seemingly random voltages, the lamps stayed on for about 6 seconds!!! Instead of the usual 1/2 second. I happened to be measuring V3 at the time and got a whopping ~660mV! Though I could never repeat that happening

For the most part, I got voltages around 100mV for most things. But the voltage definitely depended on how long I left the monitor off before another measurement. This is probably the most critical part of my findings, considering it renders all data useless

Another detail I noticed was that although I had been testing the monitor for quite a while, the surface on which I had the circuit board, never became warm... that probably is useless, but I figure the more details the better

So, I'm guessing this is not what you were expecting.... now what?

Well, let's rearrange the data. By teh way, this monitor uses a capacitive voltage divider to sense the output voltage and a resistor network to sense the current.

V1: 250mV V2: 273mV V3: 364mV V4: 255mV
R1: 427mV R2: 534mV R3: 109mV R4: 169mV

The first thing that stands out is V3. It is significantly higher than the others. The second thing that stands out is R3 and R4; the current sensed is much lower on the lamps connected to T302 than the lamps connected to T301. (I say 'sensed' because in one case the cause was determined to be a bad dual diode.

Now a couple of things to consider. First of all, I have heard of a 'fix' for this problem (actually a bypass) that involves using a resistor and an LED to adjust the reference voltage on the OZ694GN. I DO NOT suggest this as even a temporary cure, but it might make it easier to establish voltages if the inverter doesn't shut down.

Next, I will need a better picture of the area we are dealing with. I would like one as detailed as possible covering at least the area I've outlined.

PlainBill

[tillwhompson]

Re: Samsung SyncMaster 226BW

Okay, here you go!

And one question, does this mean that the great trouble I had in getting readings that were half-way decent doesn't indicate anything?

[PlainBill]

Re: Samsung SyncMaster 226BW

Okay, here you go!

And one question, does this mean that the great trouble I had in getting readings that were half-way decent doesn't indicate anything?

No, it means you have found a way to 'see' the problem. What is uncertain is the nature of the problem. Is it transformer? Is it the sense circuit? At this point I am suspecting the sense circuit. If you want to try an experiment, try swapping the transformers. If the lower current shows up on the other side of the board, the problem IS the transformer.

Myself, I'd rather play with a meter. So once again I defaced a picture.

First - there is a solder splash circled in yellow. Did it short anything out? remove it and test. I don't think it had anything to do with the problem, but....

If the solder splash wasn't responsible, in the area circled in gray, I am interested in the resistances at D205, D206, D3207, and D208. I've numbered the pins on one of them. Measure the resistance from 1 to 2, 2 to 3, and 3 to 1. Also, if your DMM has a diode check function, measure the voltage across the junctions. I think it should be Red lead on 1, black lead on 2, then red lead on 2, black lead on 3 but I may have it backwards. Of course, if you find a shorted doide, no need to continue.

Next, in the areas circled in lime green, I am interested in the resistances of Q211, Q212, Q213, Q214, and again, the voltage drops of the junctions.


For your information, I've also attached a simplified drawing of an inverter based on the same chip.

PlainBill

[tillwhompson]

Re: Samsung SyncMaster 226BW

Alright... I haven't measured the diode readings yet, but here is the resistance info... I've sorted them from left to right in your 'defaced' picture.

Unfortunately, although I'll admit I don't know what I'm doing... it looks like these guys are all fine... but I'll let you be the judge of that

Resistance of components:

D207:
1 -> 2: 353 OHMS
2 -> 3: 553 OHMS
3 -> 1: 0 OHMS

D206:
1 -> 2: 354 OHMS
2 -> 3: 553 OHMS
3 -> 1: 0 OHMS

D208:
1 -> 2: 353 OHMS
2 -> 3: 553 OHMS
3 -> 1: 0 OHMS

D205:
1 -> 2: 353 OHMS
2 -> 3: 551 OHMS
3 -> 1: 0 OHMS

Q213:
1 -> 2: 427 OHMS
2 -> 3: 956 OHMS
3 -> 1: 4 OHMS

Q214:
1 -> 2: 397 OHMS
2 -> 3: 880 OHMS
3 -> 1: 957 OHMS

Q212:
1 -> 2: 424 OHMS
2 -> 3: 948 OHMS
3 -> 1: 4 OHMS

Q211:
1 -> 2: 397 OHMS
2 -> 3: 870 OHMS
3 -> 1: 956 OHMS

Oh and a little lesson maybe someone can learn from. I discharged all the capacitors on the board first, and also had to play with the setting on my DMM to get resistance values that made any since... yea stupid me trying to measure resistance on the smallest scale

Diode measurements to come.

[ansi]

Re: Samsung SyncMaster 226BW

in buzznjackal's first image attachment, there's a component next to C111 and C112, i'm not sure what it is but i removed mine thinking it was some sort of cap but it isn't. i need to replace it. i have the same exact board as his attachment and i can't seem to locate the caps i removed as i did it last week before i left on vacation. now i'm back and can't find them, heh. any ideas on what that is so that i can replace it? also, the large cap C105 that lies on it's side, has some very small leads on it (the replacement). I guess i need to order another one with longer leads on it?

BuzzNJackal's atachment: https://www.badcaps.net/forum/attach...chmentid=11728

[retiredcaps]

Re: Samsung SyncMaster 226BW

in buzznjackal's first image attachment, there's a component next to C111 and C112, i'm not sure what it is

I can't quite make out the writing on the PCB, but if it starts with the letter L, it is an inductor. That is, it will say L101 or something like that.

[ansi]

Re: Samsung SyncMaster 226BW

I can't quite make out the writing on the PCB, but if it starts with the letter L, it is an inductor. That is, it will say L101 or something like that.

yeah it's labeled L101, thank you. Still need to try and figure out which one to get though. I have to track down the old ones and see if i can't figure it out from there.

[ansi]

Re: Samsung SyncMaster 226BW

alright i've managed to locate the removed caps and the missing inductor. you think it would be alright if i soldered the old one back into it? thinking about doing this for the large cap as well but i removed the plastic coating on it and can't determine the position of the negative lead now. probably be safer just to reorder that item. yeah?

[PlainBill]

Re: Samsung SyncMaster 226BW

alright i've managed to locate the removed caps and the missing inductor. you think it would be alright if i soldered the old one back into it? thinking about doing this for the large cap as well but i removed the plastic coating on it and can't determine the position of the negative lead now. probably be safer just to reorder that item. yeah?

The inductor is nothing more than a number of turns of wire around a ferrite core. It's pretty much immune to any abuse short of physical damage. Yes, you can go ahead and reuse it.

You can use the cap with the short leads. Just use the leads from the old one to 'bridge' the gap. Don't play guessing games with which is the negative lead. Getting it wrong would result in the equivalent of a shotgun going off when the monitor was plugged in. Unless, of course, you look forward to explaining the 'explosion' to your significant other, the neighbors, and the local police force.

PlainBill

[ansi]

Re: Samsung SyncMaster 226BW

Does it matter if the inductor is in there backwards? I don't believe it is but there are no visible markings to determine it. but being as it's a wire wrapped around a core it should do the same thing even if it were reversed? and the bridging the gap idea, +1 to you good sir. I hadn't even thought of that. Thank you.

[ansi]

Re: Samsung SyncMaster 226BW

you guys rock. my monitor is up and running again and it only ran me about $12 to fix it. thanks!