Samsung 244T ...stuck in standby

[tuk]

Re: Samsung 244T ...stuck in standby

caps replaced, turned on and it worked perfectly for 2-3hrs ...even the power light was functioning normally again( before it would not turn off)

then the screen went dark ..I thought the pc had cashed, but on reboot I couldn't see the post screen

the screen starts off black, then the pc is turned on..after a few secs the screen lightens slightly(backlight on?) ..but no display ...'no signal' message not present either ...and no flashing stuck in standby as before..just solid green regardless if signal is present or not

pressing the powerlight turns off the 'button light' and dims the monitor to black(off)

[tuk]

Re: Samsung 244T ...stuck in standby

the screen starts off black, then the pc is turned on..after a few secs the screen lightens slightly(backlight on?)

just to correct this slightly ..it does this when monitor is powered on, even if signal cable is disconnected from the pc

[tuk]

Re: Samsung 244T ...stuck in standby

the monitor power light comes on and stays solid green ..a few seconds later the screen lights up but stays black ..I'm assuming this is the back light ...the OSD menu doesn't appear .. basically apart from the backlight coming on there is no display...even with no signal cable the power light is solid green when it should be blinking(standby) ...connecting the signal cable makes no difference to the above

I'v found the service manual for the 244T ..but unsure where to start given the symptoms and history?

pdf 4 ..troubleshooting: don't think this applies to me?
pdf 9 ..powerflow voltage chart
pdf 10 ..wiring diag
pdf 15 ..schematic

forum would not host service file so
service manual

[PlainBill]

Re: Samsung 244T ...stuck in standby

the monitor power light comes on and stays solid green ..a few seconds later the screen lights up but stays black ..I'm assuming this is the back light ...the OSD menu doesn't appear .. basically apart from the backlight coming on there is no display...even with no signal cable the power light is solid green when it should be blinking(standby) ...connecting the signal cable makes no difference to the above

I'v found the service manual for the 244T ..but unsure where to start given the symptoms and history?

pdf 4 ..troubleshooting: don't think this applies to me?
pdf 9 ..powerflow voltage chart
pdf 10 ..wiring diag
pdf 15 ..schematic

forum would not host service file so
service manual

There are a few possible failure points and it's difficult to know which you are seeing.

First, most monitors display 'No Signal', then go to standby if the signal cable is not hooked to a computer. Dell monitors usually display a color box that slowly steps across the screen. Other options are possible; I don't know what this Samsung does. Universally I would expect a monitor to shut off the LCD panel and backlight, and go to an amber display if the signal cable is hooked to a computer that is off.

Further, LCD panels can either pass the backlight when not receiving power (that is normally the case with lcd panels used in monitors) or block the backlight when not receiving power (commonly found in TVs).

IF the green power LED responded normally, I would suspect you had the second type of panel and eithr a problem with the cable to the LCD panel, or a bad panel card.

By the description. it appears there is a problem with the signal card; it is not generating video information for the LCD panel, and is not processing video information from the computer properly.

PlainBill

[tuk]

Re: Samsung 244T ...stuck in standby

First, most monitors display 'No Signal', then go to standby if the signal cable is not hooked to a computer. Dell monitors usually display a color box that slowly steps across the screen. Other options are possible; I don't know what this Samsung does.

when the 244T is working normally but no signal, it shows the same 'no signal' box stepping across the screen then goes to standby ..in this case it wont show anything ..including its own OSD menu

IF the green power LED responded normally, I would suspect you had the second type of panel and eithr a problem with the cable to the LCD panel, or a bad panel card.

I have just noticed it only stays solid green when the signal cable is unplugged from the pc ..I have no idea if this was the case before. ..once more with feeling:

pc( turned off ) connected to monitor(flashing/standby):

Turn on pc, post beep
power led stops flashing and goes solid green
backlight comes on
no display

Turn off pc
power led goes from solid green back to flashing/standby
-----------

so the monitor is responding to the pc input ..just not displaying the signal data being sent

By the description. it appears there is a problem with the signal card; it is not generating video information for the LCD panel, and is not processing video information from the computer properly.

...my electronic knowledge is sketchy to say the least, what is the best plan of attack with these symptoms?, given that I have just replaced the caps and it worked perfectly for 2-3 hours ...should I start by testing the psu board ..and if so should I test the individual cap voltages ..or just measure the voltage leaving the board ..according to the 'power flow chart' in the service manual the SMPS should have 13V at output

e2a:
dunno if this is relevant ...but it was working ok for a few hours after the cap replacement...I was watching a full screen video which froze but the sound was still playing normally ...I though the pc had crashed ..but I'm thinking now it was the monitor that crashed and froze the image ..as the sound was not interrupted(pc audio) ..& ctrl-alt-del etc did not work(it did but I couldn't see it) ...on reboot the post screen didn't display and the new problem was born

[tuk]

Re: Samsung 244T ...stuck in standby

#delete me

[PlainBill]

Re: Samsung 244T ...stuck in standby

when the 244T is working normally but no signal, it shows the same 'no signal' box stepping across the screen then goes to standby ..in this case it wont show anything ..including its own OSD menu


I have just noticed it only stays solid green when the signal cable is unplugged from the pc ..I have no idea if this was the case before. ..once more with feeling:

pc( turned off ) connected to monitor(flashing/standby):

Turn on pc, post beep
power led stops flashing and goes solid green
backlight comes on
no display

Turn off pc
power led goes from solid green back to flashing/standby
-----------

so the monitor is responding to the pc input ..just not displaying the signal data being sent


...my electronic knowledge is sketchy to say the least, what is the best plan of attack with these symptoms?, given that I have just replaced the caps and it worked perfectly for 2-3 hours ...should I start by testing the psu board ..and if so should I test the individual cap voltages ..or just measure the voltage leaving the board ..according to the 'power flow chart' in the service manual the SMPS should have 13V at output

e2a:
dunno if this is relevant ...but it was working ok for a few hours after the cap replacement...I was watching a full screen video which froze but the sound was still playing normally ...I though the pc had crashed ..but I'm thinking now it was the monitor that crashed and froze the image ..as the sound was not interrupted(pc audio) ..& ctrl-alt-del etc did not work(it did but I couldn't see it) ...on reboot the post screen didn't display and the new problem was born

It is a common fallacy to believe Post hoc ergo propter hoc (after this, therefore because of this).

There is a quick test to perform. Disconnect the cable inking the signal card to the LCD panel. Turn on the monitor. If you get a white screen, the problem is the signal card. If you get a black screen, the problem is the LCD panel (or more properly, the panel card AKA tcon).

AHH, crud. Add PROBABLY to the above statements. The way I understand it, when a pixel is updated the signal card sends the information to the panel card. Pixels that are unchanged do not get updated , therefor at any instant the complete display pattern is stored on the panel card (tcon). And somewhere the datalink has been broken.

PlainBill

[tuk]

Re: Samsung 244T ...stuck in standby

AHH, crud. Add PROBABLY to the above statements. The way I understand it, when a pixel is updated the signal card sends the information to the panel card. Pixels that are unchanged do not get updated , therefor at any instant the complete display pattern is stored on the panel card (tcon). And somewhere the datalink has been broken.

I have a volt meter(1000vDC/700vAC) & an old Tektronics 2215A 60MHZ ...I'm thinking I need to trace/test the path from dvi input-->tcon output ..can I use a volt meter to test the signal path or do I use the scope?

[PlainBill]

Re: Samsung 244T ...stuck in standby

I have a volt meter(1000vDC/700vAC) & an old Tektronics 2215A 60MHZ ...I'm thinking I need to trace/test the path from dvi input-->tcon output ..can I use a volt meter to test the signal path or do I use the scope?

You, sir are a genius!!! Use the oscilloscope. It isn't fast enough to see the actual waveforms but should be capable of indicating some activity.

As far as I know, the pinout of the LVDS cable is standardized; I've attached a picture showing it. Ignore the pin numbers on the IC - that will vary with the GPU, of course. The pins on CN104 are the ones that should be of interest.

I'd say it isn't necessary to follow the signals all the way through from VGA or DVI connector to the output of the panel card. The waveforms are obviously getting to the GPU, the question is if the drive signals are getting to the LVDS connector, and if they are getting from the LVDS connector on the tcon to the proper chip there.

PlainBill

[tuk]

Re: Samsung 244T ...stuck in standby

thanks bill ..this will be my project over the holidays