Samsung SyncMaster 226BW

[jetadm123]

Re: Samsung SyncMaster 226BW

This is the video of what the video does. http://www.youtube.com/watch?v=fVbHsfY1A3Q

Welcome to the forum and thanks for sharing your YouTube video! One can only imagine what people will think (those folks who aren't aware of this forum) when they come across your video and try to figure out what's going on. Who knows, it could generate a lot of "buzz" and go viral! Seriously, follow retiredcaps advice on the previous page and we'll go from there.

[mastertheknife]

Re: Samsung SyncMaster 226BW

Hi everyone,

I have a 226BW with the exact same problem, I opened the monitor and indeed there are some bad caps there.
I ordered the nichicon caps recommended in this forum and other websites and replaced all 6 capacitors (820x2,680x2,330x1,47x1) successfully.
I made sure the polarity is correct and all the connections (those ccfl connections) are good and in the right order.
I closed the 226BW, powered it up, it was good, the backlight was working like new.
However that only lasted around 5 seconds, after that it began to flicker so i turned off the monitor and then i saw a white screen (strange?)
Now no matter what i do, the backlight just doesn't come on, however the monitor works, i can confirm that with a flash light.
I'm desperate, any ideas or what can i test\measure?

Thank you,
mastertheknife.

[jetadm123]

Re: Samsung SyncMaster 226BW

Hi everyone,

I have a 226BW with the exact same problem, I opened the monitor and indeed there are some bad caps there.
I ordered the nichicon caps recommended in this forum and other websites and replaced all 6 capacitors (820x2,680x2,330x1,47x1) successfully.
I made sure the polarity is correct and all the connections (those ccfl connections) are good and in the right order.
I closed the 226BW, powered it up, it was good, the backlight was working like new.
However that only lasted around 5 seconds, after that it began to flicker so i turned off the monitor and then i saw a white screen (strange?)
Now no matter what i do, the backlight just doesn't come on, however the monitor works, i can confirm that with a flash light.
I'm desperate, any ideas or what can i test\measure?

Thank you,
mastertheknife.

1) A "white screen" generally means that the backlight is on, but the LCD panel is not proceesing video input.

2) However, you're saying that the backlights are off, but you can see an image with a flashlight.

3) I guess you mean #2 above?

4) Apparently, there are several versions of the power supply used for this monitor. Please post some photos of it. Entire board, top and bottom.

5) There's probably a fuse either on top of the board or a surface mount fuse on the bottom that feeds the inverter section. Usually marked FXX?. Check to see if it's open.

6) Also, verify that (I think) 24V? is feeding the inverter section.

7) The two 8-pin chips contain dual mosfets. Check them for shorts.

[mastertheknife]

Re: Samsung SyncMaster 226BW

1) A "white screen" generally means that the backlight is on, but the LCD panel is not proceesing video input.

2) However, you're saying that the backlights are off, but you can see an image with a flashlight.

3) I guess you mean #2 above?

4) Apparently, there are several versions of the power supply used for this monitor. Please post some photos of it. Entire board, top and bottom.

5) There's probably a fuse either on top of the board or a surface mount fuse on the bottom that feeds the inverter section. Usually marked FXX?. Check to see if it's open.

6) Also, verify that (I think) 24V? is feeding the inverter section.

7) The two 8-pin chips contain dual mosfets. Check them for shorts.

Hi, thanks for your reply.

1, 2 and 3) I will try to explain it better. After replacing the capacitors and powering up the monitor, the monitor was working fine for few seconds, including the backlight, it was working and i could see my desktop.
After a few seconds, the backlight began to flicker real bad, so i turned off the monitor. After turning off the monitor (using the power button) i saw a white screen (the backlight was still working here but flickering) for about half a second or a second and then the monitor was off.
I opened the monitor to inspect if any capacitors has failed early but no luck, they all look good.
After powering the monitor again, i couldn't get the backlight to work. I can see a picture but no backlight, i can confirm the picture by using a flash light. I hope the ccfls aren't fried.
After turning off the monitor, the white screen for about half a second still happens (although with the backlight off, i noticed it using a flash light).

This is an S panel 226BW so i am really interested in fixing it, i probably messed up something up badly during my soldering.
When soldering the 47uf capacitor i accidently put too much solder, i think i might have caused a short, so i later i tried to remove the excess solder with wick, scratching the PCB a little on the way because it was almost impossible to get off for some reason.

4) This seems to be the Rev 1 of the power supply board.

5) I noticed two fuses on the board (marked F301 and F101), both are open.

6) Sorry i'm not good with electronics. Where do i need to check?

7) They all seem OK.

I took pictures of the board, including the capacitors i used and the board prior to replacement capacitors.

[retiredcaps]

Re: Samsung SyncMaster 226BW

5) I noticed two fuses on the board (marked F301 and F101), both are open.

If you have a multimeter, set it to the lowest ohms setting. Touch your 2 probes together.

1) What is the reading of the 2 probes together?

2) Measure and report the ohms for F301.

3) Do the same for F101.

A good fuse should measure less than 1.0 ohms.

[mastertheknife]

Re: Samsung SyncMaster 226BW

If you have a multimeter, set it to the lowest ohms setting. Touch your 2 probes together.

1) What is the reading of the 2 probes together?

2) Measure and report the ohms for F301.

3) Do the same for F101.

A good fuse should measure less than 1.0 ohms.

1) The reading of the 2 probes are 1.3 ohms, i guess this old multimeter is not calibrated properly.

2) F301 is 1.3 ohms

3) F101 is also 1.3 ohms

Thank you,
mastertheknife.

[retiredcaps]

Re: Samsung SyncMaster 226BW

1) The reading of the 2 probes are 1.3 ohms, i guess this old multimeter is not calibrated properly.

2) F301 is 1.3 ohms

3) F101 is also 1.3 ohms

Your fuses are good. Your multimeter may need a new battery. We have seen this a lot lately. Old/weak batteries give inaccurate readings.

PS. When you say "open fuse", it is blown (bad).

[retiredcaps]

Re: Samsung SyncMaster 226BW

It is not uncommon to have more than 1 problem with a monitor.

Changing the caps was the first step. The next is to measure your inverter transformers.

1) Put your multimeter on 2000 ohms (if manual).

2) Measure and report the resistance between the 2 yellow dots.

3) Do the same for the 2 red dots.

[mastertheknife]

Re: Samsung SyncMaster 226BW

It is not uncommon to have more than 1 problem with a monitor.

Changing the caps was the first step. The next is to measure your inverter transformers.

1) Put your multimeter on 2000 ohms (if manual).

2) Measure and report the resistance between the 2 yellow dots.

3) Do the same for the 2 red dots.

2) The yellow dots gives 1076 ohms in 2K mode (the multimeter actually displays 1.076)

3) The red gives 1089 ohms in 2K mode (the multimeter actually displays 1.089)

Thank you again,
mastertheknife.

[retiredcaps]

Re: Samsung SyncMaster 226BW

2) The yellow dots gives 1076 ohms in 2K mode (the multimeter actually displays 1.076)

3) The red gives 1089 ohms in 2K mode (the multimeter actually displays 1.089)

The two inverter transformers measure fine.

There are two 8 pin ICs just to the left of the dip arrow. I believe it is U308 and U309?

Look at the part number. Find the datasheet on the Internet. The datasheet should tell you which pins are source, gate, and drain.

Measure the resistance between S-G, S-D, and G-D. Report readings for all pins and both chips.

[mastertheknife]

Re: Samsung SyncMaster 226BW

The two inverter transformers measure fine.

There are two 8 pin ICs just to the left of the dip arrow. I believe it is U308 and U309?

Look at the part number. Find the datasheet on the Internet. The datasheet should tell you which pins are source, gate, and drain.

Measure the resistance between S-G, S-D, and G-D. Report readings for all pins and both chips.

U302 and U303 are those 8pin ICs. Part number for both is AP4511GED and is a dual mosfet.

EDIT: I didn't test them properly, re-doing the test now in the proper mode.

Thanks again,
mastertheknife.

[mastertheknife]

Re: Samsung SyncMaster 226BW

The board didn't let me edit the previous post, so here it is:

First chip:
S1->G1 = ~1840 ohms
S1->D1 = ~1660 ohms
G1->D1 = infinite

S2->G2 = ~700 ohms
S2->D2 = ~550 ohms
G2->D2 = ~1350 ohms


Second chip:
S1->G1 = ~1840 ohms
S1->D1 = ~1660 ohms
G1->D1 = infinite

S2->G2 = ~730 ohms
S2->D2 = ~550 ohms
G2->D2 = ~1380 ohms

This was in diode test mode. In resistance mode (including 2 million) all tests show infinite.

Thanks again,
mastertheknife.

[mastertheknife]

Re: Samsung SyncMaster 226BW

I opened up another 226BW (a working one) and tried its power supply board in this 226BW and the monitor worked like new, this rules out the ccfl, the panel or the signal board from being the problem.

both boards are identical. I tried checking things with the multimeter on both boards in order to locate a mismatch\problem but no luck in finding the problem.
I noticed a short in the bad board near an IC (I suppose its the inverter IC). After fixing that short and verifying with the multimeter, the backlight came on but only for a few seconds, because then it began to flicker and now its off again and power cycling the monitor doesn't bring it back on (just like before fixing the short).

The white screen for half a second still happens when the monitor is off, i noticed that the white comes from the center of the screen and then spreads to the corners.
This doesn't happen with a good power supply from another 226BW.

Can it be the new capacitors? can it be my bad solder near the 47uf cap?
Any ideas\clues?

Thanks, mastertheknife.

[PlainBill]

Re: Samsung SyncMaster 226BW

I opened up another 226BW (a working one) and tried its power supply board in this 226BW and the monitor worked like new, this rules out the ccfl, the panel or the signal board from being the problem.

both boards are identical. I tried checking things with the multimeter on both boards in order to locate a mismatch\problem but no luck in finding the problem.
I noticed a short in the bad board near an IC (I suppose its the inverter IC). After fixing that short and verifying with the multimeter, the backlight came on but only for a few seconds, because then it began to flicker and now its off again and power cycling the monitor doesn't bring it back on (just like before fixing the short).

The white screen for half a second still happens when the monitor is off, i noticed that the white comes from the center of the screen and then spreads to the corners.
This doesn't happen with a good power supply from another 226BW.

Can it be the new capacitors? can it be my bad solder near the 47uf cap?
Any ideas\clues?

Thanks, mastertheknife.

SWAG, but the white screen pattern sounds like the panel is loosing power. IT'S supply is from the logic board. So that leads back to the 5V output of the power supply being suspect.

PlainBill

[mastertheknife]

Re: Samsung SyncMaster 226BW

SWAG, but the white screen pattern sounds like the panel is loosing power. IT'S supply is from the logic board. So that leads back to the 5V output of the power supply being suspect.

PlainBill

Hi PlainBill,
I am not really knowledgeable when it comes to electronics, can you give me a clue what to check\where\how ?

Thank you,
mastertheknife

[jetadm123]

Re: Samsung SyncMaster 226BW

Hi PlainBill,
I am not really knowledgeable when it comes to electronics, can you give me a clue what to check\where\how ?

Thank you,
mastertheknife

On other power supplies, you normally have a 5V and 12V output. The 5v supplies the logic board and the 12V the inverter section. In your case, it looks like you have you have a single output that drives everything. Try measuring the voltage of the the device mounted on the heatsink above the 3 inline caps on the right side of your photo. Use a mounting screw for your negative probe and measure the output voltage on the middle leg of the device. Looks like the voltage output of the power supply is stamped on the board, but I can't read it.


You also mentioned that you cleared a short near some IC. Why do you think it was a short and what IC was it near?

[mastertheknife]

Re: Samsung SyncMaster 226BW

I found something interesting, i found how to reproduce the backlight working and the white screen:

If i discharge all capacitors on the board (by shorting them with a flat screw driver) and then plug in the monitor, the backlight is on and i see a solid white screen. If i hit the power button to turn on the monitor the white screen disappears and then i see the monitor searching for source(analog\digital thing - it was unplugged) and after few seconds the backlight flickers and then turns off (however the monitor still works, can confirm with a flash light).

So it appears there are 2 problems:
1) The logic board doesn't keep the panel off when it needs to be off (monitor off), this is probably the reason it displays a white screen, however, it didn't happen before replacing the capacitors and doesn't happen with another power supply from another 226BW.
2) The backlight works if i discharge all capacitors, but only for about 5 seconds, then it begins to flicker and after 2-3 seconds the backlight is off.

I took out the 47uf capacitor and put the original one back in, no luck, same problem.

Ideas\clues are welcome,
mastertheknife.

[mastertheknife]

Re: Samsung SyncMaster 226BW

Thank you jedadm123, i will do that test right away.

Looks like the voltage output of the power supply is stamped on the board, but I can't read it.

Thats correct, on the board it says:
MODEL: IP-45130A
INPUT: 100-240V~50/60Hz 1.2A
OUTPUT: (CN2) 13V (DC) 1.5A (Level3)
(CN3~CN6) 700V~/7.5mA

You also mentioned that you cleared a short near some IC. Why do you think it was a short and what IC was it near?

I attached pictures of it in the good board and in the bad one. Maybe it was there, maybe i did it accidently with the soldering iron.
I fixed it already but it doesn't seem to be the problem, the backlight working after that was probably because i discharged all capacitors prior to the soldering.

Thanks again,
mastertheknife.

[mastertheknife]

Re: Samsung SyncMaster 226BW

On other power supplies, you normally have a 5V and 12V output. The 5v supplies the logic board and the 12V the inverter section. In your case, it looks like you have you have a single output that drives everything. Try measuring the voltage of the the device mounted on the heatsink above the 3 inline caps on the right side of your photo. Use a mounting screw for your negative probe and measure the output voltage on the middle leg of the device.

Measured 13.24VDC with monitor both on and off.

Thanks again,
mastertheknife.

[mastertheknife]

Re: Samsung SyncMaster 226BW

I found a bad resistor on the power pin going to\from the signal board, on the good board it measures 91,000 ohms and on the bad board around 350 ohms.
Can this be the cause of the issue?

mastertheknife