JVC 49cf890 - Fire TV - no picture but sound

[dskall]

Re: JVC 49cf890 - Fire TV - no picture but sound

This is just a hobby for me. So there is no fun for me in board swapping. But I understand others are here just to find out what board to replace to get their TV's working again.

[vinceroger69]

Re: JVC 49cf890 - Fire TV - no picture but sound

This is just a hobby for me. So there is no fun for me in board swapping. But I understand others are here just to find out what board to replace to get their TV's working again.

same as me then, just a hobby i also like saving stuff from landfills any repaired items i pass on to family or freinds and just charge them for any parts ive had too buy.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

So, it is not the main board The new one arrived yesterday but it is still the same.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

post 2 picture 3 under the ribbon cable connector there is a fuse marked N what votage do you get on each side of that one meter lead on metal tv chassis then test voltage each side.

Will check this when i find some free time

[vinceroger69]

Re: JVC 49cf890 - Fire TV - no picture but sound

Will check this when i find some free time

Im pretty sure you will find its fine though atleast you have ruled a bad mainboard out. So now because you only get a flash of back lights i think that may need to be your next check have you got a back light tester? can you post some good clear pictures of the backlight connector on the power supply as you maybe able too check the voltage there with a multi meter.
This maybe the schematic for you board but there are a few revisions of this psu

[dskall]

Re: JVC 49cf890 - Fire TV - no picture but sound

From here on out it will likely be component level repair.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

Im pretty sure you will find its fine though atleast you have ruled a bad mainboard out. So now because you only get a flash of back lights i think that may need to be your next check have you got a back light tester? can you post some good clear pictures of the backlight connector on the power supply as you maybe able too check the voltage there with a multi meter.

Actually i do not get backlight flash only. The backligiht is working and i can see it from the back holes. Unfortuanetlly cannot upload video as this forum does not accept .mp4 video formats. I wll upload clear photo of the backlight connector in few mins....

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

Ok, here we go and some photos of the backlight connector. I believe that should be:

I have got -123V on that connector and maybe you can see that the backlight is on.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

post 2 picture 3 under the ribbon cable connector there is a fuse marked N what votage do you get on each side of that one meter lead on metal tv chassis then test voltage each side.

12.3V both ends on that fuse

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

I can feel that part here is getting very hot:

[dskall]

Re: JVC 49cf890 - Fire TV - no picture but sound

You will need to start checking voltages and for shorts.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

I checked all resistors - all looks good except that R100:

I have got short both ends. Is that resistors also?

Can you advise which voltages i need to check please?

Thanks.

[dskall]

Re: JVC 49cf890 - Fire TV - no picture but sound

Will need good pictures all along board.

[lotas]

Re: JVC 49cf890 - Fire TV - no picture but sound

R100 - 0.1 Om

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

[lotas]

Re: JVC 49cf890 - Fire TV - no picture but sound

You do not need to check the resistors, but the blocking ceramic capacitors (they should not have low resistance, short circuit). Check what resistance across induktors is relative to gnd.

[dskall]

Re: JVC 49cf890 - Fire TV - no picture but sound

Voffe, vone, vcc avvd and test points with voltages marked. All points should have correct voltages. Disconnected those points should not be low ohms from ground to test point.

[lotas]

Re: JVC 49cf890 - Fire TV - no picture but sound

And check the resistance between these induktors and gnd.

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

Voffe - 0V
Vss - 0V

Cannot find Vone and VCC AVD. Found VONE here but not sure which point to measure:


Also found few Vcc point but not AVD.

On this 32V point i have got 0V

[Dobsuk]

Re: JVC 49cf890 - Fire TV - no picture but sound

And check the resistance between these induktors and gnd.

2 of them are giving me aproxx 145Ohms and the other 2 nothing.