Nash LCD TV NTFT-3203CX screen on then off

[chandra]

Nash LCD TV NTFT-3203CX .When on the tv,some times a flash on screen then dark.some times it gets on and then if there is no input signal it shows plain screen.If I give the input video signal the screen goes to dark.Anybody can help.But the standby led remains green.

[ProDave]

Check the backlights. It's common with many sets for the backlights to come on at power up, then trip a second or two later.

If it is that, we can give some more tips what to look for.

[chandra]

Yes.Same. The back lights are on for one second and then goes off.The power 24volts are goes to 0volt.But the 5v and power on supply is steady.Tv is not going to standby.

[chandra]

I checked the backlights are ok.When switch on some time a flash at screen or sometime the TV name NASH displaying 10 secondds.

[ProDave]

Okay, the problem is a fault on the inverter board.  Something is causing it to trip.  Common culprits are capacitors or the transformers, sometimes even just dry joints.

Do you have the service manual or a circuit for the inverter?

Have a look and see what chip it uses.  If it's an OZ960, there's a neat trick to fix it while you diagnose the fault proper.

[chandra]

I checked the inverter board.It uses OZ9966SN chip.24 pin smd package

[ProDave]

The "trick" is to connect an LED from pin 10 on the OZ960 to ground, which is pin 6 on the OZ960. This disables one of the protection modes.

You will need to look up the datasheet for the OZ9966 and compare it with the OZ960 first to see if it's broadly the same device and if so which is the equivalent of the OZ960's pin 10.  IIRC the OZ960 is a 20 pin device.

[chandra]

I searched internet,anywhere I did not find the schematic or datasheet for the chip OZ9966SN.Anybody have it.Please.

[niculae_pavel]

partial pins for oz9966

6=gnd
7=rft
8=ct
9=sync
10=lct
11=b-dim
12=v-sens
13=i-sens
14=sst-cmp
15=timer
16=ovfb
17=uvls
18=a-dim
19=ena
20=vdd