Samsung Syncmaster 223BW - blank screen..

[spuzzum]

Re: Samsung Syncmaster 223BW - blank screen..

Hi Cathary, thanks for the suggestion. EPROM corruption was suggested by Davi.p but I don't have access to a reprogrammer.. maybe it's time to invest in one..

Do a google for 24cxx eeprom programmer, and make one yourself.. cost like $5 in parts, and it's a pretty simple circuit. There's even a 4-pin socket on the board that I'm betting is for programming.

But from what I've been reading.. you can dump and flash the chip directly from the desktop. Here's a post from a thread where somebody wrote a fixed eeprom back to his monitor with a GUI...

http://ubuntuforums.org/showthread.p...1#post12002011

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Hi Cathary, thanks for the suggestion. EPROM corruption was suggested by Davi.p but I don't have access to a reprogrammer.. maybe it's time to invest in one..

[cathary]

Re: Samsung Syncmaster 223BW - blank screen..

Hello guys.

Has anyone troubleshoot the logic board?

All I'm going to write is just what I read online, nothing is tested.

Reading different forums, I saw that most of the techs (including me) are trying to find a faulty electronic component. Nothing bad till now, but not all to accomplish the final job.

Reading some polish/russian forums (using google translate), I realized that I overlooked the bios (firmware) role. Itself, the firmware might be responsible for this kind of situation.

There is a .*bin file (arabic forum) that can be rewritten in the flash memory. This procedure is called, from what I understand, "dumping eeprom".

There are some SPI FLASH programmers and dedicated software, like RT809F High speed USB programming unit BIOS programmer, that can do the job. This is just an example.

If someone has the possibility to test the file, I'll be more than greatful.

If anyone else has a different oppinion or way of working, please share it .

[Davi.p]

Re: Samsung Syncmaster 223BW - blank screen..

But you say that A21SC is an eeprom 24c02.. i don't see it in alldatasheet...

[selldoor]

Re: Samsung Syncmaster 223BW - blank screen..

24co2 is at digikey data sheets available

Sorry I have been a bit busy and will be for a few weeks

http://www.digikey.co.uk/product-sea...980?k=%2024c02

24co8 is at digikey data sheets available

http://www.digikey.co.uk/product-sea...980?k=%2024c08

[Davi.p]

Re: Samsung Syncmaster 223BW - blank screen..

Perhaps 10 minutes is not enough time to look?

What do you want to say?
I've searched all them with alldatasheet.com and after with yahoo

I believe
A21SC is an eeprom 24c02
...

How do you found them?

Datasheets are available for all?

??

[selldoor]

Re: Samsung Syncmaster 223BW - blank screen..

It's difficult to find datasheets...

Perhaps 10 minutes is not enough time to look?
I believe
A21SC is an eeprom 24c02
A81SC is an eeprom 24c08
MX 12G 25L 1005MC is a CMOS Serial Flash MX25L1005MC-12G
A393F 805 is a KIA393P/F

Datasheets are available for all?

[Davi.p]

Re: Samsung Syncmaster 223BW - blank screen..

Let's imagine for some minutes that the words "programmed obsolescence" has any sense, if you find the points where dc-dc ps convertion has the output and you watch for continuity with pins on that sop8 chips, we can find the vcc pins of them, now i've read some few things about resetting a serial eprom, is by shortcircuiting the pins rx-tx when powering up if i remeber, on some models, lost for lost we can maybe find that resetting that with a certain flag set by a certain obscure routine... then you have to make many shorts between pins, usually those 2 are near.. to be safe disconnect lvds flat, shorting other pins than vcc is not risky, bye.

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Yes, I had that problem too... and the version of the logic board they use in the official manual is not the same as the one in this monitor. I think BudM is right. it's a matter of replacing the logic board or binning the screen sadly.

[Davi.p]

Re: Samsung Syncmaster 223BW - blank screen..

It's difficult to find datasheets...

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Sure, From left to right they are as follows;
IC202 = A21SC J803
IC603 = A393F 805
IC203 = A81SC Q802 (or 0802 is hard to tell)
IC201 = MX 12G 25L 1005MC

[Davi.p]

Re: Samsung Syncmaster 223BW - blank screen..

Hi, can you tell me a list of the markings on all 8 pin ICs (sop8)?

[budm]

Re: Samsung Syncmaster 223BW - blank screen..

That means the MOSFET is switching on OK, so the logic signal from the controller is not being sent to turn on the MOSFET.

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Sorry Bud, I've been away... When I touch the grounded 100 Ohm resistor to the pin with 4.7v all the other pins on the MOSFET show 5.2V as long as it's connected, and then the voltage slopes back to 0V (i.e. around 4-5 s) when it's removed.

[budm]

Re: Samsung Syncmaster 223BW - blank screen..

At this point, you can try using 100 Ohm 1/4 w resistor on that pin with 4.7V and Ground to see if you do get 5V output.
I have a feeling you have have corrupt EEPROM or something bad on this logic (scaler) board.

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

thanks bud

[budm]

Re: Samsung Syncmaster 223BW - blank screen..

Too bad, the service manual does not have the same logic board as yours. I will look further.

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Helping hands have arrived. I'm getting no fluctuation in the voltage on the pin we think is the gate when pressing the power button (i.e. a steady 4.7v), or when switching on a PC connected to the VGA port. The pin registering 5.2V doesn't fluctuate either. I get no voltages on any other pins when pressing the button or switching on the PC either.

[budm]

Re: Samsung Syncmaster 223BW - blank screen..

OK, the resistance is quite normal, so the voltage on post 4 needs verification to see if we do not have 5V output is due to bad MOSFET or due to no control signal at the Gate.

[neuralnet]

Re: Samsung Syncmaster 223BW - blank screen..

Very sorry Bud, my mistake.. I'm misreading the digital meter.. it's not 0, it's off the scale. If I was using my analogue one I'd have seen which way the needle went

I'm actually getting 9900 ohms on C435, and the same on C436. Similarly, C629 initially reads 150 ohms and then goes up to 1190 ohms. I really appreciate your assistance. Thanks.