Samsung 266BW - blue power light stays off

[retiredcaps]

Re: Samsung 266BW - blue power light stays off

I'll post followup reports next week. Happy labor day.....

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.

[montreal]

Re: Samsung 266BW - blue power light stays off

Thanks for your encouragement on my problem. Since posting, I have examined the video board and identified the DC to DC converter chip that transforms 14 VDC to 5VDC. Next week I will have a chance to see exactly where the 5 volts is not coming through.

As for the missing blue LED power light, there appears to be two surface mounted LED diodes the size of pin heads soldered to the small circuit board that carries the ON/OFF pushbutton. Much smaller than a typical LED, these compact structures are a minimalist solution.

I'll post followup reports next week. Happy labor day.....

[PlainBill]

Re: Samsung 266BW - blue power light stays off

Retiredcaps must be taking the afternoon off. He's earned the break. Note the links in my signature. First, verify you used the proper caps. That's a common error.

Next, follow the links on taking pictures and take pictures of both the bottom and top of the power supply and the logic card. Attach them to your next post.

PlainBill

[Rtech]

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.

[montreal]

Hello, this is my first post and any feedback on my problem will be greatly appreciated.

My neighbor gave me his 2 year old Samsung 226BW after it died completely on him a few months ago. Having been an electronics hobbiest for some time, I welcomed the chance to try to give it a new life.

I found that the monitor would have a black screen even though the blue power light was on.

If I disconnected the computer video cable (DVI) and left the monitor attached to the 120 volt AC, then after about 30 minutes I would finally get that moving message on the screen requesting an analog or digital connection. Once the video connection was made, then the monitor worked fine until it fell into Power Save mode and eventually cooled down.

Once cool, the monitor would not wake up and the blue light continued to flash. The screen would stay black. The blue power light eventually went off and would only come back on if I disconnected the video cable (DVI). Reconnecting the video cable would make the light go off again.

If I permanently disconnected the computer cable and plugged the monitor back into the 120 Volt AC source, then eventually it would warm up enough to work again.

Once I stopped using the Power Save option, the monitor continued to work OK in screen saver mode. I found that if I had to reboot the computer, my monitor was OK as long as I restarted everything quickly.

Last night I had to shut down the PC to clean the CPU fan. The delay getting the monitor back on-line was too long and this time, the monitor's blue power light never came back on.

So after discovering this web site, I opened up the monitor and determined that three 25 volt capacitors on the power supply board were bulging. I changed these 3 caps as well as 3 other 25 volt types which were not bulging.

Unfortunately that did not change anything for the better.

What I do know is that apart from producing the high voltage for the backlamp, the power supply board produces 14 volts DC for the display (logic) board.

From what I can tell, the logic board receives the 14 volts DC via a 9 wire flat cable and the logic board converts this 14 volts to a number of lower voltages including 1.8 volts, 3.3 volts, and 5 volts. The logic board sends 3 signals back to the power supply board (DimA, DimB, and ON/OFF). I conclude that the DimA/DimB signals tell the lamp's inverter to set the backlight level and the ON/OFF signal orders the lamp inverter to go into Power Save mode.

My problem is that I have no 5 volts appearing on the display logic board at any of the locations marked as 5 volt test points. The high voltage 170 volts DC, and 1.8 Volts DC and 3.3 Volts DC are all OK.

The 5 volts that the video board needs does not appear to be produced on the power supply board as is the case with other Samsung models.


So I would conclude that locating where the 5 volts is created on the video board might be the first step to solving my problem.

As well I am trying to discover where the actual blue power light comes from. When I disassemble the power switch, I see no additional blue LED.

Any advice?

Thanks