Samsung 2493HM Monitor

[rippergr]

Hello,
I have a samsung 2493HM Monitor which have a black screen and blinking blue led.
There is no bad caps whith cisual inspection and no burning marks on any component.
I checked 5,3V and 24V and I have no voltage in any of them
Can someone help me?

[rippergr]

Re: Samsung 2493HM Monitor

For some reason the photos of my previous post was lost so I upload them here.

[budm]

Re: Samsung 2493HM Monitor

First thing you need to do is to remove those bad glues and inspect the components legs and parts for corrosion and damages.
This is what bad glue can do to the board.
You can also search badcaps.net for 'BN44-00195'

https://www.badcaps.net/forum/showthread.php?t=34692

[rippergr]

Re: Samsung 2493HM Monitor

I already remove the glue. I show earlier that post. Maybe it doesnt show clearly on the photos.
There is no damage in any leg of component or component itself.

[budm]

Re: Samsung 2493HM Monitor

I can still see lots of glues, especially on the high voltage caps in the 12V/24V power supply section.
You must be getting the standby Voltage otherwise you will not have any LED indicator, so I do not see why you said you do not have any Voltages.

[rippergr]

Re: Samsung 2493HM Monitor

Ok I removed most of the glue altough I could inspect the legs of the components even if they didnt show clearly on the photo.
I also checked the transofrmer widings and they seem ok.
If the standby voltage is in S_B pins then I have 5.3V there.

[rippergr]

Re: Samsung 2493HM Monitor

Here are the voltages I have from the back of the board

[budm]

Re: Samsung 2493HM Monitor

You need to find out when the PS-ON is present you do have around 400VDC on the main filter cap.

[rippergr]

Re: Samsung 2493HM Monitor

Where should I check for PS-ON voltage?
and for the main filter cap I just measure it with power and it should give me 400v?

[budm]

Re: Samsung 2493HM Monitor

Where should I check for PS-ON voltage?
and for the main filter cap I just measure it with power and it should give me 400v?

Look at the connector of the power supply board that goes to the main board, you can see the pin labels.'
400VDC will be present on the main filter cap when the PS-ON is present to turn on the PFC Voltage booster circuit and the 12V/24V switched power supply section.

[rippergr]

Re: Samsung 2493HM Monitor

I have no voltage neither in 400V cap nor the PSON

[budm]

Re: Samsung 2493HM Monitor

I have no voltage neither in 400V cap nor the PSON

The PS-ON (pin 1 of the connector CN851, <1VDC = OFF, >2.5VDC = ON) is generated by the main/Logic when the monitor is turned ON.
So if there is no PS-ON then there will be no Boosted Voltage, no 12V/24V power supply.
Is the monitor connected to running PC?

[rippergr]

Re: Samsung 2493HM Monitor

No I just give power to board. Should I connect a runnng pc to enable the power to pson?

[budm]

Re: Samsung 2493HM Monitor

You need to have all the boards connected otherwise the power board will not get the command signals.
Most monitor will turn on for a few seconds or minutes and then goes into standby if the video signal is not detected.

[budm]

Re: Samsung 2493HM Monitor

BTW, you can also force the power supply without having it connected to other board by putting a 470~1K resistor between the standby power supply pin and the PSON pin.

[rippergr]

Re: Samsung 2493HM Monitor

I connect all the boards still the blue light blinking no voltage on PSON . ON filter cap I have instantly about 100V and instantly dropping to 20V and then continue dropping.
I have it connected to a pc that is running

[budm]

Re: Samsung 2493HM Monitor

I connect all the boards still the blue light blinking no voltage on PSON . ON filter cap I have instantly about 100V and instantly dropping to 20V and then continue dropping.
I have it connected to a pc that is running

How do you put the probe to measure the Voltage of the main filter cap?
Did you put the probes on each legs of the cap?
Your country is 220~240VAC, right? Then the dcv on the main filter cap in standby mode should be more than 300vdc.

[rippergr]

Re: Samsung 2493HM Monitor

My country is 220V and I put the black probe to a ground and check the voltage on + of the cap.
Am I doing it wrong?

[budm]

Re: Samsung 2493HM Monitor

My country is 220V and I put the black probe to a ground and check the voltage on + of the cap.
Am I doing it wrong?

You are doing it wrong, when you are making the measurement in the primary side of the circuit, the GND ref. for the meter will be the negative leg of the main filter cap.
When making the measurement in the secondary/cold side of the circuit, you can use the chassis GND as the GND ref. for your meter (if the secondary GND is tied to the chassis).

[rippergr]

Re: Samsung 2493HM Monitor

You are doing it wrong, when you are making the measurement in the primary side of the circuit, the GND ref. for the meter will be the negative leg of the main filter cap.
When making the measurement in the secondary/cold side of the circuit, you can use the chassis GND as the GND ref. for your meter (if the secondary GND is tied to the chassis).

Thanks I didn't know that.
According to your directions I measured the capacitor correctly and I have 315V