i am rereading this
http://temelelektronik.info/ders/download/lcdmrx.pdf

and began check from the begining...

After checking is there good power supply for supply ic the next step is
"Testing the secondary output voltages"

On the picture i see two big diodes near the capacitors.

Where to look for these diodes on my board -
https://drive.google.com/drive/folders/1_8QmPuUGFPDw7BsY3Xfukx5qXcArBsyB

thanks in advance

...maybe are the ones on the heat sink but i want to be sure..

 

The diodes on the transformer secondary are, I believe, as arrowed below.

 

Measuring the voltage on one of them i see :

https://drive.google.com/open?id=19JsIm_qSADJ8zU28ctx1hJ1FJbP_2YXX

Why am i seeing so many voltages and what value to take for truth?

 

Where exactly are the meter leads connected?
The diodes have an AC voltage coming in and a DC voltage coming out. Your meter is set to a DC voltage range and if it is connected so that the meter sees an AC component in the voltage then you might well get that sort of response from the meter.

 

yes. i have measured now these :
the common cathode(the middle pin) of the both secondary diodes and the max value shown on the DMM is on one 0.6 on the other one 0.8 on range 20V
So the both are dead ?

 

?

 

They are probably fine. Typical voltage across a silicon junction diode (not Schottky) is 0.7volts.

 

I should expect output voltages from these shottky ->

 

Those readings...try testing them using the diode test function of your DVM.

How to Test a Silicon Diode with a Multimeter

 

so. i have new one analogue meter since today.

The both diodes :
x1 ohm check - low ohms reading, oposite probes - no reading
x10k full scale(let`s say) and with oposite probes absolutely no reading

My Esr meter does show:


So where should be the truth and why?!

 

Does your meter have a diode test mode? Use that if you have it.

Otherwise, you can use the AC voltage range to measure the inputs (the anodes) of the rectifiers to see whether there is a large signal on the diode. If there is, and there is very little DC output that points to a diode problem.

If the AC side of the diode shows a very small signal then you should look upstream for the problem since you have shown that your diodes are not shorted.

 

Measuring the voltage on one of them i see :

https://drive.google.com/open?id=19JsIm_qSADJ8zU28ctx1hJ1FJbP_2YXX

Why am i seeing so many voltages and what value to take for truth?

The diodes are Dual Shottkey types in a T0220 package, they will have a Vf of 250mV to 550mV on "Diode Test" using a DVM .

The centre pin is Cathode.

 

obviously i have shorted STK0765 which is power mosfet - i hear beep when check drain to source with curcuit check mode.

I will look for one new and then put it on board and the other desoldered elements too and will see what will be.

 

Otherwise, you can use the AC voltage range to measure the inputs (the anodes) of the rectifiers to see whether there is a large signal on the diode. If there is, and there is very little DC output that points to a diode problem.

I think this is a switch mode supply so the AC may be too high frequency for good readings on a standard multimeter.
The diode test range is a much better bet.