Samsung 214tw

[almoodie]

I have a Samsung 214tw which failed to come on. Took the monitor apart and found 5 swollen caps on the SMPS/Inverter board. Replaced all electrolytics and checked for cold/frosted joints, found none.
On testing the power supply light glows continuously but screen is dark except for the moving message box which says "Check signal cable". Cable and signal from computer is good as it works just fine with another LCD monitor. Connection is VGA.
Since I have the moving display box, that means the backlight is working and it follows that the power supply is working to some extent.
I'm an amateur at this, what do I do next?

[mutant]

Re: Samsung 214tw

Did you double check those connections especially those ribbon cables? I'm sure someone can chime in with another suggestion.

[almoodie]

Re: Samsung 214tw

MORE INFO

On testing the power supply light glows continuously but screen is dark except for the moving message box which says "Check signal cable, Digital". This not right as the monitor is being fed an analog signal (VGA). Don't have a DVI output on my video card so cannot test for digital input. Will search for S-Video cable tomorrow.

[almoodie]

Re: Samsung 214tw

MORE INFO

I have another, working, 214tw and took the power supply/inverter board out and put it in the non-working monitor, non-working monitor came to life.
So I have a problem with the power supply/inverter board. Can I test the output voltages on this board when I have it out or do I need to have it connected to the monitor.
Suggestions on what to look for please.

[PlainBill]

Re: Samsung 214tw

MORE INFO

I have another, working, 214tw and took the power supply/inverter board out and put it in the non-working monitor, non-working monitor came to life.
So I have a problem with the power supply/inverter board. Can I test the output voltages on this board when I have it out or do I need to have it connected to the monitor.
Suggestions on what to look for please.

Have it connected to the monitor. In the lower right hand corner of the board, next to the connector leading to the logic card, is a list of the signals on each pin of that connector. Measure them.

PlainBill

[almoodie]

Re: Samsung 214tw

Have it connected to the monitor. In the lower right hand corner of the board, next to the connector leading to the logic card, is a list of the signals on each pin of that connector. Measure them.

PlainBill

Plain Bill,

Pin numbers are listed first, then the values listed on the legend on the board, then the actual readings:

1 PWH DIM 57 mV
2 GND 57 mV
3 GND 57 mv
4 GND 57 mV
5 13V 57mV
6 13V 57mV
7 13V 57mV
8 A-DIM 57mV
9 ON/OFF 57mV

Thanks for your help.
Al Moodie.

[almoodie]

Re: Samsung 214tw

Plain Bill,

Please ignore previous values they were taken with the boards connected to each other but removed from the chassis.
With boards connected and in the chassis (logic output is NOT connected to lcd screen) values are as follows.

Pin numbers are listed first, then the values listed on the legend on the board, then the actual readings:

1 PWH DIM 0 mV
2 GND 57 0 mV
3 GND 0 mv
4 GND 0 mV
5 13V 0.1 mV
6 13V 0.1 mV
7 13V 0.1 mV
8 A-DIM 0 mV
9 ON/OFF 0 mV

Al Moodie.

[PlainBill]

Re: Samsung 214tw

Plain Bill,

Please ignore previous values they were taken with the boards connected to each other but removed from the chassis.
With boards connected and in the chassis (logic output is NOT connected to lcd screen) values are as follows.

Pin numbers are listed first, then the values listed on the legend on the board, then the actual readings:

1 PWH DIM 0 mV
2 GND 57 0 mV
3 GND 0 mv
4 GND 0 mV
5 13V 0.1 mV
6 13V 0.1 mV
7 13V 0.1 mV
8 A-DIM 0 mV
9 ON/OFF 0 mV

Al Moodie.

Did you take these measurements with the monitor plugged in?

PlainBill

[almoodie]

Re: Samsung 214tw

Did you take these measurements with the monitor plugged in?

PlainBill

Here are the conditions. Both boards removed from chassis. Both boards connected to each other. Both boards connected to display. AC power applied. Voltages are:

1 PWH DIM 57 mV
2 GND 57 mV
3 GND 57 mv
4 GND 57 mV
5 13V 57mV
6 13V 57mV
7 13V 57mV
8 A-DIM 57mV
9 ON/OFF 57mV

As you can see voltages differ depending on whether boards are connected to chassis.

Al Moodie.

[PlainBill]

Re: Samsung 214tw

Here are the conditions. Both boards removed from chassis. Both boards connected to each other. Both boards connected to display. AC power applied. Voltages are:

1 PWH DIM 57 mV
2 GND 57 mV
3 GND 57 mv
4 GND 57 mV
5 13V 57mV
6 13V 57mV
7 13V 57mV
8 A-DIM 57mV
9 ON/OFF 57mV

As you can see voltages differ depending on whether boards are connected to chassis.

Al Moodie.

Try doing it this way: Measure from your choice of pins 2,3, or 4 to pins 1, 8, 9, and your choice of 5, 6, or 7.

PlainBill

[almoodie]

Re: Samsung 214tw

Try doing it this way: Measure from your choice of pins 2,3, or 4 to pins 1, 8, 9, and your choice of 5, 6, or 7.

PlainBill

OK, I believe I have it now:
Relative to pin3

pin 1 = 3.5 mV
pin 6 = 13.11 V
pin 8 = 0.5 mV
pin 9 = 11.5 mV

Al.

[PlainBill]

Re: Samsung 214tw

OK, I believe I have it now:
Relative to pin3

pin 1 = 3.5 mV
pin 6 = 13.11 V
pin 8 = 0.5 mV
pin 9 = 11.5 mV

Al.

Now compare them to the working board.

PlainBill

[almoodie]

Re: Samsung 214tw

Now compare them to the working board.

PlainBill

For some unknown reason this monitor has now burst into life and I cannot get it to fail. Pin voltages are now:

Relative to pin3

pin 1 = 42.7 mV
pin 6 = 13.11 V
pin 8 = 7.0 mV
pin 9 = 2.9 mV
which are almost exactly the same as on my "good" power supply/inverter board.

Perhaps the changes in the voltages suggest to you what may have caused the previous failure. I am now using the monitor as my daily workhorse to see how it performs over time. Thanks for your help.
Al.

[PlainBill]

Re: Samsung 214tw

For some unknown reason this monitor has now burst into life and I cannot get it to fail. Pin voltages are now:

Relative to pin3

pin 1 = 42.7 mV
pin 6 = 13.11 V
pin 8 = 7.0 mV
pin 9 = 2.9 mV
which are almost exactly the same as on my "good" power supply/inverter board.

Perhaps the changes in the voltages suggest to you what may have caused the previous failure. I am now using the monitor as my daily workhorse to see how it performs over time. Thanks for your help.
Al.

No, they don't. Most of the designations are obvious: Gnd and 13V are obviously the outputs of the power supply. On/Off is also obvious - the control for the inverter. PWH DIM and A-DIM are less obvious; they imply that there are TWO methods of dimming the display. Usually the CCFL brightness control is an analog signal, somewhere around 1-3 volts is common. ON/OFF would typically switch between 0 Volts and 5 Volts. Milli-volt differences don't make sense.

The old rule applies here - "Problems that go away by themselves will return by themselves." I suspect a bad solder joint.

PlainBill