Samsung 2253LW

[selldoor]

Re: Samsung 2253LW

and oh by the way I used 1000uF/25V since its hard to find 820uF here.. will that hurt the power supply??

That is ok you are safe to go one step higher. Low ESR would be good but I guess you have to use what you can get.

If the Fuse you mention is in the circuit to power the back lights then obviously they will not come on. This may also distort some readings on other voltages

[budm]

Re: Samsung 2253LW

That green fuse is for feeding the B+ to the inverter circuits, so if is blown then more likely that you do have shorted out MOSFETs that drive the Inverter transformer.
Need to get the P/N of the SMD Mosfets to get the pin out then check for low resistance readings between S and D pins of the MOSFET.

[jahjhai]

Re: Samsung 2253LW

greetings everyone...

i manage to replace the fuse resistor and happens to check and suspect that the mbr20100ct which is a switch mode power rectifiers could be faulty. i am not aware about the proper voltage data on these components and needs assistance from everyone, since i dont have any clue on what will be their voltage reading. if only i have a schematic diagram for the mckinley 22 power supply of the 2253lw samsung monitor i can fix this with no problem at all..

regards to everyone out there...

[budm]

Re: Samsung 2253LW

@JAHJHI: leave that green fuse out off the circuits, then power up the power supply board by itself and see if you are getting any voltages on those caps you have replaced, if you do, then the MBR20100CT is not the problem.
Does the MBR20100 checked out as shorted out?
https://cdn.badcaps-static.com/pdfs/...d01a5d055f.pdf

[jahjhai]

Re: Samsung 2253LW

@budm, i'll give it a try anyways, can you provide me some voltage reading on the MBR20100CT, its hard to guess with the correct voltages for this power supply, im kinda lost since i dont have schematic diagram for this.,

by the way i got some concern with the supply voltage for the 13V, i checked the voltage on it and gives me a 16V reading.. were should i start checking and also the other component with the 6pins, im not sure if that also is damage..

thanks in advance
happy holidays to everyone...

[budm]

Re: Samsung 2253LW

Since you are reading 16V instead of 13v, what do you read on the 5V out put?

[Davi.p]

Re: Samsung 2253LW

i understand very few, why don't you post the voltage readings on the output connector? is the double diode ok? Is the main mosfet on primary ok? Where is the green fuse resistor?

[budm]

Re: Samsung 2253LW

The reason I ask if the 5V is OK or not is that both voltages are generated by the same transformer, if the one goes up, another one will be up also since it is driven by the same transformer, the regulation feedback is doen most of the time by monitoring the 5V output because the logic circuits require good steady 5V to run properly, the 13/16V for the backlights inverter circuit does not require regulated voltage to run.
The green fuse is fed by the B+ (13~16V) power supply to run the backlights circuit. See pictures in post 10. Since there is no load on the 13-16V line, the volage will be higher until the inverter circuits are running.

[Davi.p]

Re: Samsung 2253LW

Sorry for my last post, i have read for error only the first page..

[jahjhai]

Re: Samsung 2253LW

greetings... holidays make me busy fixing my things.. now i have the voltage reading for the components needed.. the 5V voltages are in good condition, yes i do understand logic circuits, they need 5 volts to operate to get low or high signals.

anyway the MBR20100CT has two terminals with 1 common cathode. the first i test has voltage reading of 5.33V on each anode.. while the other MBR20100CT has a higher voltage which is 18.88V and i tested this without the fuse resistor to determine whats goin on...

also i have some voltage data for the DM0565R
Pins in Order:
1. Drain = 302V
2. GND
3. Vcc = 14.82V
4. FB = 0.647V
5. NC
6. Vstr = 296V

AC supply is 220V

with a fuse resistor voltage is 16V
without it becomes 18V

backlight nevers lights up..

[budm]

Re: Samsung 2253LW

The power supply is working, otherwise you will not be getting the good 5V, and the 16VDC. The problem is in the inverter circuit or it is not getting the BL_ON from the main board. No need to concentrate on the power supply section, that is not the problem.
I need good clear pictures of the top and bottom side of your board so I can give you the test points to test.

[jahjhai]

Re: Samsung 2253LW

here are the pictures you have requested...

thanks and advance happy new year...

[budm]

Re: Samsung 2253LW

OK, please give me the label of those pins and the P/N of those two MOSFETs.

[lexwalker]

Re: Samsung 2253LW

greetings... holidays make me busy fixing my things.. now i have the voltage reading for the components needed.. the 5V voltages are in good condition, yes i do understand logic circuits, they need 5 volts to operate to get low or high signals.

anyway the MBR20100CT has two terminals with 1 common cathode. the first i test has voltage reading of 5.33V on each anode.. while the other MBR20100CT has a higher voltage which is 18.88V and i tested this without the fuse resistor to determine whats goin on...

also i have some voltage data for the DM0565R
Pins in Order:
1. Drain = 302V
2. GND
3. Vcc = 14.82V
4. FB = 0.647V
5. NC
6. Vstr = 296V

AC supply is 220V

with a fuse resistor voltage is 16V
without it becomes 18V

backlight nevers lights up..

Those readings are kinda on the high side, as usually on the 2253LW the voltage to the inverter section should be around 13V to 14V. You can also force the backlight to power up manually (without using the Dscaler board)...

here are the pictures you have requested...

thanks and advance happy new year...

Have you replaced all the capacitors at the secondary side yet? Looks like el-cheapo capacitors there especially on the inverter side...

[budm]

Re: Samsung 2253LW

Pin 8 on the power supply board is the BL_ON (ON-OFF) control pin, you should see it toggle when the monitor is power on and off (you have to hook up to running PC).
>2V = ON, 0 = OFF.

Read this link, I think it has the same board as yours: IP-49135 please verify, I cannot clearly read it on your board.
https://www.badcaps.net/forum/showthread.php?t=22267

1- b-dim
2- 13v
3- gnd
4- gnd
5- 5.1v
6- 5.1v
7- a-dim
8- on/off
9- 3.3v
10- led
11- key 1
12- key 2

[lexwalker]

Re: Samsung 2253LW

Pin 8 on the power supply board is the BL_ON (ON-OFF) control pin, you should see it toggle when the monitor is power on and off (you have to hook up to running PC).
>2V = ON, 0 = OFF.

Well, actually no need to hook to PC when testing the inverters. If the inverters and backlights are working then will get a white screen/display (since the Tcon is not used). Sometimes I power up the inverters using an external power supply for testing (whenever the main power section on the board failed or having problems)...

[budm]

Re: Samsung 2253LW

If he using the force on method then he does not need to use to have it hooked up to running PC. But he needs to find out first if the logic board is sending the BL_ON signal or not.

[lexwalker]

Re: Samsung 2253LW

If he using the force on method then he does not need to use to have it hooked up to running PC. But he needs to find out first if the logic board is sending the BL_ON signal or not.

First things first, find out whether the backlights can be switched on to make sure that its not the inverter problem. Then can start looking at the backlight control signal which either comes directly from the Dscaler I.C or is driven by a transistor on the Dscaler board. And those capacitors, IMHO, needs to be changed as well before any further work/diagnostics (to remove as much as possible variables)...

[budm]

Re: Samsung 2253LW

Since he had blown fuse that feed the b+ to the inverter circuit, he should check for short circuit first by looking at the MOSFET as I have shown in the diagram in the inverter section, and make sure b+ is present to run the inverter. At this point I am not where he at with that blown fuse. He can keep putting in new fuse if he does not locate the problem first. He can also check the current draw using meter in DC AMP mode if not shorts are located.

[jahjhai]

Re: Samsung 2253LW

Pin 8 on the power supply board is the BL_ON (ON-OFF) control pin, you should see it toggle when the monitor is power on and off (you have to hook up to running PC).
>2V = ON, 0 = OFF.

Read this link, I think it has the same board as yours: IP-49135 please verify, I cannot clearly read it on your board.
https://www.badcaps.net/forum/showthread.php?t=22267

1- b-dim
2- 13v
3- gnd
4- gnd
5- 5.1v
6- 5.1v
7- a-dim
8- on/off
9- 3.3v
10- led
11- key 1
12- key 2

hello there, i read the link you provided to me, and the issue is some how similar to my problem.

they have the same pins as well and yes all of it is working good except pin 2 which is getting high around 16V(with fuse resistor) - 18V(no fuse resistor)

anyway the issue on that forum was not known if e3sgr was able to fix his monitor. anyway im not giving up on this yet.. later i will be doing a lot tests on it.. including how he tried to put in a 1k resistor to force it to turn on the backlights.

thanks for all the help on this case, also i would like to inform lexwalker that the issue is that the inverter of the lcd is not working but the ccfl light are good since i tested them using a different inverter.

it will be better if there is known good board that i can compare with voltage readings or a schematic diagram that tells us all the details and test points of all the components that should be checked.

i'll post up some data later.. for now gonna go out for some time to relax..