Samsung 266BW - blue power light stays off

[cadillacman]

Re: Samsung 266BW - blue power light stays off

we will have to see what they want to do. I think i may fix this for myself if they tell me to toss it.

the model is misleading by the way, its actually a 22" monitor.

[PlainBill]

Re: Samsung 266BW - blue power light stays off

you were right on the money plainbill.

plugging in one ccfl plug at a time, i could see a glow about 1/3 of the way across the diffusers(lcd removed) except one plug did nothing. It was in the top ccfls, the one with the pink/wht wires. I pulled the diffusers and stuff down, the ccfl in question is literally fried, about 2mm missing, wire is fried going into the lamp, hell even the main diffuser got a little crispy in one spot..

Now comes the fun part of trying to find these. It needs all four, theyre pretty rough looking. I cant believe the picture was not pink looking.

Replacement CCFLs are easy - CCFLWarehouse or their eBay store, Plasmo Industries are a good source. Determining the diameter and length is a little more difficult. They aren't cheap, but a 26" monitor is worth it.

PlainBill

[cadillacman]

Re: Samsung 266BW - blue power light stays off

you were right on the money plainbill.

plugging in one ccfl plug at a time, i could see a glow about 1/3 of the way across the diffusers(lcd removed) except one plug did nothing. It was in the top ccfls, the one with the pink/wht wires. I pulled the diffusers and stuff down, the ccfl in question is literally fried, about 2mm missing, wire is fried going into the lamp, hell even the main diffuser got a little crispy in one spot..

Now comes the fun part of trying to find these. It needs all four, theyre pretty rough looking. I cant believe the picture was not pink looking.

[PlainBill]

Re: Samsung 266BW - blue power light stays off

picky picky

heh.. i may or may not have tome tonight, but if i do i will take a bunch more pics, i definately do not have an issue posting there if it helps everyone out...

im the meantime a revised pic from the op..

It definitely looks like the two CCFLs are in series. Give it a try and see if any one CCFL will light up.

PlainBill

[cadillacman]

Re: Samsung 266BW - blue power light stays off

picky picky

heh.. i may or may not have tome tonight, but if i do i will take a bunch more pics, i definately do not have an issue posting there if it helps everyone out...

im the meantime a revised pic from the op..

[PlainBill]

Re: Samsung 266BW - blue power light stays off

ok i have 4 backlight connectors... are you saying power it on with one connector at a time to see if i have a odd man out?

Yes. Although the CCFLs may not work unless both of a pair are hooked up. I could tell more by looking at a picture of the bottom of the power supply, but SOMEONE posted 7 pictures and didn't include the one I needed. (The picture of the bottom of the signal card is exceptionally useless.)

PlainBill

[cadillacman]

Re: Samsung 266BW - blue power light stays off

ok i have 4 backlight connectors... are you saying power it on with one connector at a time to see if i have a odd man out?

[PlainBill]

Re: Samsung 266BW - blue power light stays off

Here we go again with a not to simple issue even though i thought it was heh..

Ok so again this would power on to a grey screen for about 2 secs then shit off, blue power led still on.

Took it apart, apparently the sales manager at work had it apasrt, the t-con cable was disconneced. Reconnect, now i get a picture for those 2 seconds before it shuts off. 2 seconds to black kind of issue going on here...

SO i pulled the powerr supply/inverter board. Found one obious bad cap, rest are some no name krap. Replaced all caps on the power supply, fixerd some krap solder, recheck- SAME... ugh.. ive ohmed the inverters and theyre not open and read the same between each other... the backlights are not pink or flickering, it powers up to a nice pic and backlights just shut off.



WHere do i go from here? anyway to mod this to make backlights just frickin stay on?

The best way to make the backlights stay on is to fix the problem.

Disconnect one of the backlight connectors, then turn on the monitor. Do the backlights come on? Now reconnect the first connector, disconnect the other, and turn on the monitor again. Do the backlights come on with the same brightness?

PlainBill

[cadillacman]

Re: Samsung 266BW - blue power light stays off

Here we go again with a not to simple issue even though i thought it was heh..

Ok so again this would power on to a grey screen for about 2 secs then shit off, blue power led still on.

Took it apart, apparently the sales manager at work had it apasrt, the t-con cable was disconneced. Reconnect, now i get a picture for those 2 seconds before it shuts off. 2 seconds to black kind of issue going on here...

SO i pulled the powerr supply/inverter board. Found one obious bad cap, rest are some no name krap. Replaced all caps on the power supply, fixerd some krap solder, recheck- SAME... ugh.. ive ohmed the inverters and theyre not open and read the same between each other... the backlights are not pink or flickering, it powers up to a nice pic and backlights just shut off.



WHere do i go from here? anyway to mod this to make backlights just frickin stay on?

[cadillacman]

Re: Samsung 266BW - blue power light stays off

my boss has one of these in his office and it just died. It will power on to a light grey screen for about a second or two then go black. blue light stays on. Going to tear into it tonight.

[montreal]

Re: Samsung 226BW - blue power light stays off

Hopefully, you didn't void the warranty by opening it up and soldering the circuit boards. The company may use the excuse that you "tampered" with it and won't honor the warranty.

Samsung has authorized a number of agencies around the world to repair their products, not just their own warranty service depot. Any authorized service depot could have temporarily replaced the bulging caps in my monitor before determining that the caps were not the cause of the continuing fault.

I put back all the original Samsung capacitors on my IP board and the Samsung warranty technician will readily observe that they are bulging and therefore their product is suspect.

Different jurisdictions have consumer laws concerning the legitimate repair of products while under warranty. Car manufacturers once insisted that the oil be changed only by an authorized dealer in order to maintain the warranty. The consumer courts where I live have ruled that an owner can change the oil him/herself and the engine warranty will be enforced as long as a proof of purchase of the oil can be provided in order to prove that the oil was changed at the prescribed service interval.

I design and build computer interface boards as a hobby and I am confident that my 45 years of electronic handywork will stand up to any scrutiny.

[jetadm123]

Re: Samsung 226BW - blue power light stays off

Since my monitor was built in October 2007, Samsung has agreed to honor the 3 year warranty and I will be shipping it to them in the next few days.


Thanks again to all who helped me along on this problem.

Hopefully, you didn't void the warranty by opening it up and soldering the circuit boards. The company may use the excuse that you "tampered" with it and won't honor the warranty.

[montreal]

Re: Samsung 226BW - blue power light stays off

As a last effort before giving up, I temporarily soldered a 100 microfarad capacitor in parallel with each electrolytic cap on the logic board in order to provide extra filtering in case any one cap was marginal.

That did not improve things so I came to the conclusion that whatever is wrong with the logic board, it is probably within the scaler or one of the two eeproms or with the flash memory.

I could never find the perfect schematic for my particular version of the 226BW. The best I could do was find a diagram for the 206/226 general series and that was a poor match to my circuit board. It turns out that the 940BW diagram has more in common with my own board except that the IP board of the 940BW furnishes the 5 volts along with the 14 volts.

Since my monitor was built in October 2007, Samsung has agreed to honor the 3 year warranty and I will be shipping it to them in the next few days.

Even though I hit a dead end on the logic board in spite of the power supply caps being bad, I did learn a lot about the design of flat screen displays and that experience alone will help me to deal with any breakdowns which may occur with my future flat screen purchases.

Thanks again to all who helped me along on this problem.

[montreal]

Re: Samsung 266BW - blue power light stays off

You may have other capacitors that are bad.. if you don't have an ESR meter then you won't have any idea.........

......Having a capacitance meter would help too.. but depending how often you plan on doing this..might be hard to justify the cost............

As stated elsewhere the blue light gets its power from the logic board.. the logic board gets it's power from the inverter board. so if a cap is bad that will stop voltage.

Thanks Solder Boy for the reply.

My blue light gets its power from the logic board. It actually gets 1.8 volts directly from the scaler chip (pin number 123). The scaler chip is fed at many pins by two sources providing 1.8 and 3.3 volts. 1.8 volts is not enough to make the blue light glow. I suspect it needs closer to 3 Volts.

There are 6 push buttons on the front panel including the power-on switch. These buttons are connected to two quad state lines which connect directly to pins 119 and 120 of the same scaler chip. These two lines normally idle at 1.8 volts. Pressing any one of these 6 buttons will set the state on these two lines to 0.0, 0.5, and 1.0 volts. The scaler chip sees a unique combination of these levels on the two lines and then decodes what button must have been pushed. All my buttons appear to be generating the correct voltages when pushed.

So if my pressing of the power-on button does not cause my blue light to come on, it may be that the scaler chip is not cycling because the crystal clock is not generating the 14.31818 Mhz. frequency needed by the chip. However my scaler chip has nevertheless managed to turn off the BL-EN signal to the inverter and the PANEL_EN signal to the panel. To do this, the scaler chip had to set pin 109 to -0.2 volts and pin 3 to 1.72 volts. I believe this suggests that the scaler chip is functioning to some degree.

The only low voltage source on the IP board is 14 volts and I am reading 15 volts on my DVM. I have changed the axial caps (there were 4 caps in parallel for a total of 3X820 and 1X330 microfarads).

Let us assume that there is no ripple on the IP board and the logic board is receiving good quality 15 volts DC.

From the photos attached to my previous post, you can see that all caps on my logic board are surface mounted ones, most of them at 10 microfarads 16 volts. None are bulging. All have the proper voltage of 1.8, 3.3, 5, and 15 measured across them. Because I don't have an ESR nor a capacitor testing meter, I cannot speak for the quality of the voltage across each cap, only the quantity. Unlike the IP board, these caps which look a lot like TO5 transistors (top hats) run relatively cool as they don't handle a lot of power.

I am reluctant to unsolder any of these surface mounted caps and if I did, I would only have axial types available to substitute. I have not seen surface mounted caps sold in my local industrial electronics store.

What I need is a scope to see if I am getting some ripple across any of these caps.

Before my monitor completely failed, I already knew that chassis heat was a factor that sustained the operation of the monitor. It needed an hour plugged into the wall on its own before the pop-up message would appear on the screen requesting a connection to the PC. And it needed to be left with an image constantly on and not allowed to fall into power-save mode, else it would fail to come back on.

I will continue to investigate.

Has anyone ever changed a surface mounted cap on a logic board and found that doing so made the repair a success?

[Solder Boy]

Re: Samsung 266BW - blue power light stays off

You may have other capacitors that are bad.. if you don't have an ESR meter then you won't have any idea. I'm finding with fixing LCD's that you start off with the easiest solutions first before you look for other culprits.

If you look at my thread re the LG Flatron Widescreen, I replaced the obvious bad caps and it still wouldn't turn on.. I have an ESR meter so I went hunting for other bad caps.. sure enough I found 2.. one was completely shot the other cap read 6 which is bad bad.

Having a capacitance meter would help too.. but depending how often you plan on doing this..might be hard to justify the cost.

As stated elsewhere the blue light gets its power from the logic board.. the logic board gets it's power from the inverter board. so if a cap is bad that will stop voltage.

Hope this helps.

[montreal]

Re: Samsung 266BW - blue power light stays off

Suggest you supply some photos,the method being described in many of Plain Bills entries,and you will probably get some help.

Please note that my monitor is the 226BW, my typo incorrectly said 266BW.

Thanks for the prompt to post photos.

I took some photos today of the front side and rear side of both the power-inverter board and the video board.

After digging up some Samsung schematics for closely related monitors, I confirmed that the only voltage produced by the IP board is 14 volts DC and the video board is correctly generating the 5, 3.3 and 1.8 volts DC. All these voltages are available at the various test points on the video board.

I tested the voltage across the power-on button and it is OK (1.8 volts). As well the blue LED glows slightly if I feed it some current from my multimeter.

However I suspect that my main scaler chip on the video board (SE758MRH-LF) may not be working properly as it is failing to send more than 1.8 volts to the blue power-on LED. I think the LED needs a few more volts to turn on.

While I do have another schematic diagram for a similar monitor (the SE85AMH scaler chip also has 128 pins like my own chip), without the full board diagram identical to my video board, it is hard to trace any further.

So I think I may have to bite the bullet on this one and say that whatever is wrong with my monitor is much more complicated than replacing some bulging electrolytic capacitors, which I did anyway.

Thanks again for your participation in this thread.

[Wrog]

Re: Samsung 266BW - blue power light stays off

Those temperatures remind me of growing up in Minnesota. You know the climate - 9 months of Winter, three months of poor sledding.

PlainBill

Or like in Chicago, there's two seasons: winter and construction.

To the OP: Great details, but as PB always says: A picture is worth a thousand words! Hopefully you're able to provide them so that it will be easier to provide troubleshooting steps.

[PlainBill]

Re: Samsung 266BW - blue power light stays off

Summer? I think we missed it this year. 6 degrees C here, but might make 21 this afternoon.
That's 43F and 72F for you Americans.

Those temperatures remind me of growing up in Minnesota. You know the climate - 9 months of Winter, three months of poor sledding.

PlainBill

[smason]

Re: Samsung 266BW - blue power light stays off

If "montreal" is actually a Canadian from Montreal, that person, like me today, is probably trying to enjoy what is left of summer here in Canada.

PS. Great detailed description of your problem. A refreshing change from some of the other recent posts.

Summer? I think we missed it this year. 6 degrees C here, but might make 21 this afternoon.
That's 43F and 72F for you Americans.

[PlainBill]

Re: Samsung 266BW - blue power light stays off

If "montreal" is actually a Canadian from Montreal, that person, like me today, is probably trying to enjoy what is left of summer here in Canada.

Meanwhile, here in Phoenix we are hoping Summer relents enough to allow us to enjoy the Labor Day holiday. High today of 111°F, but only 102°F on Monday.

PlainBill