Samsung Syncmaster 223BW

[Jitir]

Hi,

I bought a Syncmaster 223BW display knowing it was defect and hoping to only have to replace some caps. Sadly this didn't fix the display.

Issue:
When plugging the power in, the LED blinks slowly, screen stays black. Connecting a pc does not have any effect.

I did replace some old caps that were bulged. I made a picture of the old ones and tried to get some shots of the new ones. Sadly I didn't know that I had to use specific ones. I only bought caps with the same specs.

I also did measurements of some parts.
CN2 Connector on Power Supply:

1 - on/off = 0.015
2 - A-Dim = 4.56
3 - 13.5V = 14.25
4 - 13.5V = 14.25
5 - 13.5v = 14.25
6 - GND = 0
7 - GND = 0
8 - GND = 0
9 - B-DIM = 4.93

The following are from the logic board (since I dont have pin numbers, I will refer to #1 as closest to the top of the board (ribbon cable) or closest to left of the board (power cable in):

Part IC602
17-18
#1 = 3.79
#2 = 1.79
#3 = 0

Part ic204
6p806
#1 = 5.16
#2 = 0
#3 = 5.14

Part ic601
17-33g
#1 = 0
#2 = 3.25
#3 = 5.16

Part ic702
1501-50
#1 = 14.26
#2 = 5.92
#3 = 0
#4 = 5.16
#5 = 0

CN200
#1 = 0
#2 = 1.8 <- Goes to 0 when power Switch is pressed
#3 = 1.8
#4 = 0.28

It looks like IC702 is way of and IC601 is just a bit more of than 1%. Could this be causing my problems?

I only replaced 5x 820 uF and 1x 330uF caps on the power supply board. But I image as the CN2 voltages are alright there is no immediate need to replace the rest.

The 2 fuses on the power supply board seem to be alright (very low resistance).

Any ideas what else could be bad?

[redwire]

Re: Samsung Syncmaster 223BW

Your PSU voltages are look good enough, I would shotgun (=change all the electrolytics) on the IP board, it's just less hassle.

The pushbuttons on CN200 have pullup resistors to +3.3V, and then head directly into the CPU IC310 (GM5822 Genesis). They should float at 3.3V, not 1.8V so I would check the 3.3V supply to the CPU. I think it comes from IC705 (AP1501-33) after fuse ST706.
There are several voltage regulators and fuses on the CPU board, I would check them too.

I have seen caps go bad on the (IP) power board and then also take out SMD caps on the CPU board or its fuses.

[Jitir]

Re: Samsung Syncmaster 223BW

I'm really new to all this stuff, and now I'm confused.

Your PSU voltages are look good enough, I would shotgun (=change all the electrolytics) on the IP board, it's just less hassle.

Ok, I will do that. I guess I don't have to replace the big cap?

The pushbuttons on CN200 have pullup resistors to +3.3V, and then head directly into the CPU IC310 (GM5822 Genesis). They should float at 3.3V, not 1.8V so I would check the 3.3V supply to the CPU. I think it comes from IC705 (AP1501-33) after fuse ST706.

I have two questions regarding this part:

• In another thread the user stated, that the also measured 1.8V and there the values were fine.
• Where are IC310, IC705 and ST706 located? I cannot find them.

There are several voltage regulators and fuses on the CPU board, I would check them too.

Didn't I check all voltage regulators? How can I identify the rest of them?

[redwire]

Re: Samsung Syncmaster 223BW

I am using the 223BW service manual from Electro Tanya
The AC mains filter cap can fail, but it is not common and would not cause the symptoms you are seeing. The monitor has two PCB's - Logic board and (IP) power supply board. Each board has voltage regulators.
I would measure voltages on the logic board, to check the CPU power. The service manual is wrong, picture 13-1 calling the CPU Vregs "EEPROM".
It might only have 1.8VDC on the pushbuttons while sleeping but in this post it is 3.3VDC. So that may or may not be something to chase.

[Jitir]

Re: Samsung Syncmaster 223BW

I am using the 223BW service manual from Electro Tanya

That explains why I cannot find the parts you were naming Sadly I have not enough experience to either use the information in the manual or translate it to my logic board.

The monitor has two PCB's - Logic board and (IP) power supply board. Each board has voltage regulators.
I would measure voltages on the logic board, to check the CPU power.

Thanks for clearing that out! I think I already checked all Vregs (results in first post). And indeed the 5V regulator gives a a too high voltage. The text on the regulator says: "1501-50 0804BL". Can I replace it with any regulator that has 1501-50 on it?

It might only have 1.8VDC on the pushbuttons while sleeping but in this post it is 3.3VDC. So that may or may not be something to chase.

Interesting! I will measure the voltage again after replacement.

[Jitir]

Re: Samsung Syncmaster 223BW

Does anybody know which voltage regulator I can buy to replace IC702 "1501-50 0804BL" and where I could buy it?

[diif]

Re: Samsung Syncmaster 223BW

Here is the data sheet

Mouser have some in stock. http://www.mouser.de/ProductDetail/D...LjArhzsvGR9T1L