Samsung 940n wont turn on

[Rtech]

Re: Samsung 940n wont turn on

It is a schottky diode,The centre pin is the output and the two outside legs are the inputs which are then rectified,the output is then fed to caps.Check from each outside leg to the centre,on resistance,each time changing leads over, so you get 2 readings ie forward and reverse, from each outside leg to the centre.

[CroTech]

Re: Samsung 940n wont turn on

black on pin1 red on pin2 when I leave it for a couple of minutes gives 2,14kOhm
red on pin1 black on pin 2 1,95 kOhm
red on pin3 black on pin2 1,96kOhm
black on pin3 red on pin2 2,04kOhm

all measured in 20K area on the meter, left for a minut and a half to have a steady reading...

Again I found a way to turn the LED ON... shorting pin2 and pin3 on the schotky for a milisec will give the output 14,5V on the connector and the logic board shows blue LED on the switches, wondering what would happen if I connect the screen...

So i assume the problem is in the schotky? Finally?

[Rtech]

Re: Samsung 940n wont turn on

datasheet for D606 as follows:-
http://pdf1.alldatasheet.com/datashe...FMEN-210A.html

[CroTech]

Re: Samsung 940n wont turn on

A breakthrough... pluged in the screen logic board and everything, shortened pin2 and pin3 on the shotky and after a few seconds the screen is working showing no cable pluged in the wga, colors are good and everything

[selldoor]

Re: Samsung 940n wont turn on

There is a couple of basic rules in testing which I think you have missed.
I usually tell newbies

1 Resistance test (ohms) = power off
2 Voltage test = Power on.

You have perhaps been lucky this time not to blow anything but when checking resistance power should be off.

[selldoor]

Re: Samsung 940n wont turn on

I still dont know what your breakthrough means - perhaps a controller ic is stuck
or faulty caps are pulling the voltage down? perhaps rtech has an idea.

[CroTech]

Re: Samsung 940n wont turn on

You have perhaps been lucky this time not to blow anything but when checking resistance power should be off.

You assumed wrong... I know that, when using Ohm meter the instrument uses it´s own power supply to determine the resistance in this case a 9V battery inside the instrument.

The breakthrough is, I can now use my monitor again
I´ll just make a switch by soldering it on pin 2 and pin3
But I would still like to make it fully worikng again

[Rtech]

Re: Samsung 940n wont turn on

You need to change it..Doubt if you can buy the correct one easily.So you need a Schottky Diode 100V 10Amps.If your has a Plastic back on to the heatsink, then if you can only find one with a metal back then you need a fixing kit to isolate it from the heatsink.The following may help I note the first one is easily available on UK Ebay.
The mounting kit required where stated is TO220 mounting kit.
MBR20100CT (kit),MBR10100CT(kit),SB10150FCT,STPS20S100CT(kit),STPR1020Ct,STPS10AH100CTP,SB20200FC,STPS20H10(kit)

[CroTech]

Re: Samsung 940n wont turn on

will this one do http://www.ebay.com/itm/1pcs-MBR2010...item2a24addfd7

And just to mention this... When I turn on the monitor by shorting those pins I cant switch it off by pressing the button. I can only shut it down by unpluging it!

Could it be that the buttons are some how faulty?

[CroTech]

Re: Samsung 940n wont turn on

yup mine is plastic, but I can easily isolate it

[Rtech]

Re: Samsung 940n wont turn on

I would resolder the three legs on the diode before replacing,and see what happens.

[CroTech]

Re: Samsung 940n wont turn on

I´ll do that. Any thoughts on the buttons? How can I check them? I checked the cables for consistency and turned out they are good.

[Rtech]

Re: Samsung 940n wont turn on

I am pretty sure its NOT the buttons,It is the Power supply,because when you tested it on its own it was not giving the 14.5 volts OR the 5v,and the 5v is needed to work the regulators on the logic,to give 1,8v which is the LED voltage normally.

[CroTech]

Re: Samsung 940n wont turn on

Resoldered them... Nothing happend.

I´ll replace the schotky and then I ll get back to you.

Thanks for everything

[CroTech]

Re: Samsung 940n wont turn on

Changed the schotky, put on the same plastic one. Nothing changed. Now I can turn on monitor when I short pin 2 and pin 3 but later when I unplug it from AC I cant turn it ON back again with the buttons.

[Rtech]

Re: Samsung 940n wont turn on

Ok,with the Power Board ONLY, are we getting the 5v and 14.5v on the connector??

[CroTech]

Re: Samsung 940n wont turn on

Nope... 14.5V volts shows 4,8V and 5V gives 1,67V

[selldoor]

Re: Samsung 940n wont turn on

In your recent post on this thread
https://www.badcaps.net/forum/showth...294#post300294
Was the board you were talking about this one? or another

I was under the impression in post 1 that you had changed the inverter transformer for a one the same. If as you say in the other thread you used one with secondaries at 1600 ohms instead of 1200 ohms have you considered what affect that will have on the power supply? Perhaps it is just protection kicking in and you are somehow managing to override that.

[UniT3d]

Re: Samsung 940n wont turn on

Hmmm .....

Pardon me for jumping in ..... but the readings in post #10 doesn't make any sense to me ... does it make sense to anyone who understands the FSDM0465 smps controller? I'm expecting 12v on pin3 and 311v on pin6 and pin5 is supposed to be N.C. unless I'm not reading it right .....

[CroTech]

Re: Samsung 940n wont turn on

@selldoor yup I changed the transformers with the same one sunce I bought 2
I've seen people changing those with completly different modela and it worked good...

@unit3d I can recheck the voltages again on the controller