normande lcd model ND37701

[willyam1]

Hi to all.
all inputare ok exepet VGA .
no signal in vga input.
main board B.TR901E-1 8384.
FACTORY RESET?.
WILLYAM

[tom66]

Re: normande lcd model ND37701

Any pictures of parts inside?
Tried component video input, if available? That is generally shared with VGA.

[willyam1]

Re: normande lcd model ND37701

thanks tom66.
can see with scope that that the input r g b in the main ic are flickring even without connecting the vga to my laptop all voltage are ok.
also no vs and hs to the main ic it comes from an ic that act like nand gate laptop don't recognize this input maybe because the sda scl don't work or maybe the switching vga don't work its seems to me that the problem is in the main ic.
I keep on digging and see what can be the problem?

[tom66]

Re: normande lcd model ND37701

The HS/VS are important for VGA. It is possible the NAND gate IC is used as an logic inverter. If it is failed, VGA will not be detected. Try replacing that IC.

[willyam1]

Re: normande lcd model ND37701

change the ic no joy.
willyam

[tom66]

Re: normande lcd model ND37701

Check A,B input and Q output for each gate using scope. The Q should be the inverse of A and B (if A,B are connected to the same signal, it's simply the inverse of A or B.)

[willyam1]

Re: normande lcd model ND37701

by scoping the input of the hex shmit trigger that ruls the hs /vs to the main board I found that ther oly a dc signal and the outputs is revers to the input.
no signal because the laptop don't camunicat with the tv because the problem. I think that the sda scl not working because a problem.
as a result of this I think maybe e reset can help?the customer says after an electric fall the problem appear.
in the clint stor I could see that the pic appear for a few sec and then no signal.
willyam

[tom66]

Re: normande lcd model ND37701

The EDID memory could be corrupt. You can try using a program such as "powerstrip" to read the EDID memory.

[Mrx3750]

Re: normande lcd model ND37701

Are you sure the cable you're using to connect your laptop is good? I have never heard of just VGA failing on a TV.

[willyam1]

Re: normande lcd model ND37701

the cabel is good in another tv it working

[willyam1]

Re: normande lcd model ND37701

tomm66.
I will try to chang this memory from another board.
willyam

[tom66]

Re: normande lcd model ND37701

This is the little 8 pin chip hanging off the SDA/SCL lines of the VGA connector. It's an eeprom.

[willyam1]

Re: normande lcd model ND37701

thanks tomm66.
tv is working now.
problem was 3 smd resistor 75ohm this 3 connected to the vga conector R G B.
I MADE A CHECK IF ONE IS MISSING NO SIGNAL.
thanks tomm66 for your kindley efforts.
willyam

[tom66]

Re: normande lcd model ND37701

Glad to hear...but usually if one of those was bad, the appropriate colour would be too bright or missing, you have no video signal?

[willyam1]

Re: normande lcd model ND37701

sorry tomm66.
your are right im missing it with hs /vs.
the first I found 2 resi and the pic wasn't ok then I found another one that was hiding next to the conector with some black gloo on it.
willyam