Samsung Syncmaster 245BW

[jetadm123]

Re: Samsung Syncmaster 245BW

My problem is as everybody else's, black screen, power button is solid blue and no 5.3V or 24V(they are 0V). PFC stage won't start, it sits at 165V. No PS_ON voltage, only ST_BY.

If you're seeing 5V ST_BY voltage, then that's what providing power to the logic board. If you're not seeing any voltage at the PS_ON pin when you press the on/off button, then I would suggest checking the voltage regulator(s) on the logic board for proper output.

[tibimakai]

Re: Samsung Syncmaster 245BW

I have measured today the PS_ON and it has the 3.2V. I have replaced all the capacitors, 3x68Ohm resistors, 18nF capacitor, the main 82uF one also, just in case because I want to keep it for myself. Maybe these help in a way, but it still won't start.
Not sure how come I have now PS_ON?

[selldoor]

Re: Samsung Syncmaster 245BW

Hi - There are different boards used in this monitor. Perhaps you can post good clear pictures of your boards and state the Board Part Numbers.
If you have PS-ON have you tried setting it up but without the LVDS cable plugged in
to see if the the other voltages come up?

[budm]

Re: Samsung Syncmaster 245BW

Is this the same board you are working on? I drew the pin out of the board.
http://s807.photobucket.com/albums/y...msung%20245BW/

[tibimakai]

Re: Samsung Syncmaster 245BW

Yes, is the same.

[jetadm123]

Re: Samsung Syncmaster 245BW

To recap:

You're getting 5V_STBY and 3.2V for PS_ON and no output from the 24V/5V outputs. Correct?


1) Eventhough you replaced CM802, check it again for a bad solder joint, etc.

2) That leads us to the F9222L (ICM801) controller. I suggest checking the voltage at the pins specified on the schematic located somewhere in this thread. Warning: there are high voltages on some of the pins.

[tibimakai]

Re: Samsung Syncmaster 245BW

That is correct.
I haven't identify the pin numbers yet(do you know which is pin#1?), but I'm measuring high voltage at three pins, which I don't think that is a good thing.(2x 150V and 1x 168V)
I have just received in the mail the new F9222L. Should I just replace it?
I have fixed a Vizio VW42L in 30 minutes and with these two monitors(this 245BW and an Asus MK241H) I'm spending way to much time. Same goes with another Vizio VO42L.

[jetadm123]

Re: Samsung Syncmaster 245BW

Trying to find a F9222L datasheet is pretty difficult. The link below has a schematic in post #1. Also, there are 10 listed voltages for the F9222L. From what I can see, only 1 pin should be at a high voltage.

https://www.badcaps.net/forum/showth...ighlight=cm802

[tibimakai]

Re: Samsung Syncmaster 245BW

That's why I think that it's bad.

[jetadm123]

Re: Samsung Syncmaster 245BW

You can try performing a resistance check across the 2 pins reading 150V to see if it's shorted internally. Also, If you're seeing 150/168V at pins that are supposed be at low voltage, then some of the external components connected to those pins might very well be damaged. And replacing the F9222L may not solve the problem.

[tibimakai]

Re: Samsung Syncmaster 245BW

Good point. I will measure some components around the IC and I will check the resistance between those high voltages pins. I guess one pin has to have high voltage, but the other two, no.

[Philboye]

Re: Samsung Syncmaster 245BW

I recieved my new components in and replaced the 68 ohm resistor as well as most caps as I don't want to fix this monitor again.
All works well and also my bulk voltage is at 390v instead of the 165v I originally reported. I did not have to change the bulk cap CP803.
Thanks for everyones help.

Philboye

[tibimakai]

Re: Samsung Syncmaster 245BW

Good for you, I'm not that lucky as you.

[tibimakai]

Re: Samsung Syncmaster 245BW

I did some more checking and I have realized, that the F9222L it's not supplied with the right voltage. That should be like 292V as specified in the diagram. I don't have that voltage, I have only 164V.
The two other high voltage pins that I was measuring were the FET outputs from the F9222L pins 15-16.
Tomorrow I will have to check the TDA4863G chip's voltages. I have a feeling that my problem is there.
I need to repair at least this monitor or the Asus MK, since I don't have a monitor at my workplace. I have sold the one I had(22" Samsung 226BW).
I want to have two 24" monitors, one at each workbench/table.

[tibimakai]

Re: Samsung Syncmaster 245BW

The TDA 4863AG is not getting enough VCC either.
I have traced it to the ICE3B0365J which gets the right voltage, but from there the voltage received by the TDA it's very low.
Basically it looks like the 3x68 Ohm resistors won't let through enough voltage.
They receive 26.6V and after the three resistors I'm only getting 2.4V and it should be over 15V there(I assume). The only other component between the three 68 Ohm resistors and the TDA is the QB802 transistor.
The voltage drop between the three resistors is as follows(roughly what I remember), after the first one is 18.xV, after the second is 10.xV and after the third one is 2.4V.
I'm wondering what would happen if I would exclude on of the resistors?
By the way they run very hot.
Not sure where does it go the QB802? it shows DM810(can't even find it).

[budm]

Re: Samsung Syncmaster 245BW

Darn! where did you find this circuit? Do you have it in PDF?
I have to study the circuit, I have been trying to find out why those 3-68Ohms resistors keep blowing open for a long time.
Can I get the link to the diagram? Thanks.

[tibimakai]

Re: Samsung Syncmaster 245BW

It is in here a couple of pages back.

[budm]

Re: Samsung Syncmaster 245BW

The one in post 512 is not the same as yours.

[tibimakai]

Re: Samsung Syncmaster 245BW

Check post #139:
https://www.badcaps.net/forum/showth...?t=9343&page=7
It's as mine but it's not all in there.

[budm]

Re: Samsung Syncmaster 245BW

Please see the markup diagram.
If the output side of the 3-68 Ohms resistor is only have 2.4V, and it is running hot, then the load after the 20V regulator QB803 is shorted (its output is for ICM801S VCC), or the output of the regulator transistor QB802 (its output is for the VCC of ICP801S PFC Controller IC) is feeding shorted circuits, check ceramic cap CP805 which is in parallel with CP811. Also check CM811 which is connected to VCC pin7 of ICM801S.
You can lift one leg of the choke BB803 which is connected to the Output Emitter of the regulator transistor QB803. Also try lifting the Emitter leg of the QB802 to see if the voltage output of the resistor will rise up.
When the circuits operating normally, I expect to see around 35V at the input side of the 68 Ohms resistors.
Right now you have shorted circuits that is why the resistors are getting hot. You have either shorted caps or shorted ICs.