Samsung 2493HM Monitor

[budm]

Re: Samsung 2493HM Monitor

So, when the monitor is turned on or force on by the resistor between stby power supply pin and the ps-on PIN, that Voltage on the cap should go up close to 400VDC, we need o have that boosted Voltage first before going further.

[rippergr]

Re: Samsung 2493HM Monitor

Where this voltage created in the first place? I have only 310V on that cap when the monitor is on

[budm]

Re: Samsung 2493HM Monitor

It is created by the PFC controller IC, the PFC inductor and PFC diodes which are at the bottom right section of the board (looking at the board with an AC inlet at the bottom).

[rippergr]

Re: Samsung 2493HM Monitor

Can you point them ? Is there any change that something is wrong there?

[budm]

Re: Samsung 2493HM Monitor

https://www.badcaps.net/forum/attach...0&d=1468428226

ICP801S is the IC, the PFC IC, QP801S, DP801S are also for the PFC.
You have bad solder joints on the transistor QB801 which is used as the Linear regulator/switch to supply the Voltage to run the PFC ICP801S.
BTW, you need to inspect the bottom side of the board real well for cold solder joints, as you can see, one of the leg of the QB801 cracked solder ring around the left leg.

[rippergr]

Re: Samsung 2493HM Monitor

There is no bad joind in QB801.Maybe its something in the photo. I resolder the joints of the transistor just in case.
What voltage should I have in DP801S or in transistor QB801?

[budm]

Re: Samsung 2493HM Monitor

There is no bad joind in QB801.Maybe its something in the photo. I resolder the joints of the transistor just in case.
What voltage should I have in DP801S or in transistor QB801?

Report what DCV you have on all 3 legs of QB801 when PS-ON is present, make sure to use the negative leg of the main filter cap as the GND ref. for your meter because it is in the HOT side of the circuit.

[rippergr]

Re: Samsung 2493HM Monitor

PSON is never present , thts the problem.
When I just plug it on power I have 0,8V-15V in right leg and 10V-23V in middle leg. In left leg there is no voltage.

[budm]

Re: Samsung 2493HM Monitor

PSON is never present , thts the problem.
When I just plug it on power I have 0,8V-15V in right leg and 10V-23V in middle leg. In left leg there is no voltage.

Well then you need to find out why the main board is not sending the PS-ON, but I already suggested you to force on the power supply board by itself using the resistor to see if the PFC, the 12V/24V will come up or nor, if not then you have at least two bad boards. BTW, what do you mean by '0,8V-15V'? The Voltage varies that much?
QB801 is turned on by the PS-ON signal to supply the VCC to run the PFC circuit.

[rippergr]

Re: Samsung 2493HM Monitor

Using 1K resistor in SB and PSON I have 335V in capacitor and around 10V in all pins of transistor.
Is that good?

[budm]

Re: Samsung 2493HM Monitor

Using 1K resistor in SB and PSON I have 335V in capacitor and around 10V in all pins of transistor.
Is that good?

Are you sure you make the correct measurement? you cannot have 10V on all 3 pins because at least two of the pin should be 0.6V different for the transistor to be on.
If it is really 10v, that will be too low to run the PFC IC.

[asdflea]

Re: Samsung 2493HM Monitor

Hi, just one small question: does this solution/way of problem finding also work if the monitor has a black screen and the power LED is on (steady - not blinking)? If no, should I open another thread?
I got the same model 2493HM.

Thanks in advance.

[asdflea]

Re: Samsung 2493HM Monitor

Lazy as I was I just read the other threads and I will start removing those yellow glue first. Is there a chance it will work just by removing the glue? Keeping in mind my above stated symptoms?

[rippergr]

Re: Samsung 2493HM Monitor

I don't think that it will work if you remove the glue but you can see if there is a defective component under the glue.

[asdflea]

Re: Samsung 2493HM Monitor

I don't think that it will work if you remove the glue but you can see if there is a defective component under the glue.

What tool do you use to remove the glue? I have a small screwdriver here but I can't crunch the glue. It's super hard.. Do I need to soften it?

[SolderTrouble]

Re: Samsung 2493HM Monitor

A few days ago, my 2493HM started behaving just like asdflea's monitor: blue power LED is lit solid (not blinking) and black display. I plan to start a thread about it after I read more of the troubleshooting threads already available. In the meantime, here's a link to Samsung's service manual, which has troubleshooting info, wiring diagrams, schematics, etc:
http://elektrotanya.com/samsung_2493.../download.html
(It's in English.)

Is it possible for the moderator to change the vague Subject of this thread so it indicates the symptoms too? Instead of "Samsung 2493HM Monitor" how about something like "Samsung 2493HM: black screen, blinking blue LED"?

[budm]

Re: Samsung 2493HM Monitor

A few days ago, my 2493HM started behaving just like asdflea's monitor: blue power LED is lit solid (not blinking) and black display. I plan to start a thread about it after I read more of the troubleshooting threads already available. In the meantime, here's a link to Samsung's service manual, which has troubleshooting info, wiring diagrams, schematics, etc:
http://elektrotanya.com/samsung_2493.../download.html
(It's in English.)

Is it possible for the moderator to change the vague Subject of this thread so it indicates the symptoms too? Instead of "Samsung 2493HM Monitor" how about something like "Samsung 2493HM: black screen, blinking blue LED"?

BTW, the service manual does not include the power supply board diagram, only the main board diagram.

[rippergr]

Re: Samsung 2493HM Monitor

What tool do you use to remove the glue? I have a small screwdriver here but I can't crunch the glue. It's super hard.. Do I need to soften it?

No just be careful not to damage any component. I used a screwdriver myself.