Vizio XVT553SV Powers up/audio/no vid.

[tom66]

Re: Vizio XVT553SV Powers up/audio/no vid.

Looks like an LG Display panel, the sticker will say what model it is. However, it looks to use an AMTran motion interpolation processor (120/240Hz?) and combined T-con. No document LG produces will specify this. I am still confused about separate 5V on the board but it might be related to the LED backlights.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

LC550 DUH
(SC)(M1)
number under barcode is
550BP 188 3683 831B

[tom66]

Re: Vizio XVT553SV Powers up/audio/no vid.

There are some fuses on the main board (bottom of image), check if these are OK.
https://www.badcaps.net/forum/attach...7&d=1356302891

Maybe if one is blown TV will still power on/off but t-con and sound won't work.

However it does sound a lot like the common dead mainboard on Vizio TVs, related to either the eeprom or firmware.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

ok from right to left they read....5.10 V....12.15 V.....18.16 V

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

Here is the spec sheet:
You should have 12vdc on that TF1 fuse which is the B+ for running the T-CON. Also recheck that voltage on the other fuse again.
See page 8/43 for the T-CON pinout.

[tom66]

Re: Vizio XVT553SV Powers up/audio/no vid.

That is for a CCFL panel; this is LED backlit.

Also, it would appear that the T-con connection is not the same because the AMTran part is a Vizio part, not described in the LG datasheet. Unless that connection is compatible with an LG panel, which is possible, I suppose.

Hopefully it's just a blown fuse somewhere and not main board issues.

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

Yes, but the b+ for the T-CON is still supplied by that TF1 fuse which means the b+ from the switched transistor on the main board may be bad or it is not be trun on or it is missing 12v on the main board., the second fuse F4 is fed by CN2 (5-pin) which is not installed.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

TF1 reads 12.15
still.30 on the other fuse on other board

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK, take the readings as shown. I believe that is the transistor that supply the B+ for the T-CON.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

with power off..?

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK if i am right in assumeing that the test point 1 is the first pin ?
between 1 & 2 i read 952 ohms between 1 & 3 9.7 K ohms

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK, that is not the transistor then, that pin for the T-CON should be connected to the transistor and filter cap some where. You just have to find out which transistor on the main board is connected to that test point 1, it should be close to that connector. That is what I would be doing if I have the board in front of me.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK found it Q1
Got continuity on the pin on the one side. the side with 2 pins i get 0 on the one & 2.3 on the other

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

Can I see the picture of that area where Q1 is so I can mark the test points for you.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

Made mistake No readings on Q1.
Q3 is where i get the readings on

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK, as you look at the transistor with the middle pin on the top. The left pin is Base, the middle pin is Collector, the right pin is Emitter.
So please check the DC voltage an the Collector (middle pin), the Emitter pin using chassis as the ref ground with the TV switched on.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

On Q3
Collector .32
Emitter 12.16
Base 10.85

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

OK, it looks like PNP transistor, the Base Emitter is much higher than 0.6V for the Base-Emitter biasing voltage.
Put your meter in Diode mode, Black probe on the Base, the take the reaing between Base and Emitter, Base and Collector.

[Bob-62]

Re: Vizio XVT553SV Powers up/audio/no vid.

HUMMM
put meter on diode mode
nothing but when i touched pins backlight went of & then back on

[budm]

Re: Vizio XVT553SV Powers up/audio/no vid.

When you do component test, the TV must be unplugged! I hope nothing got damaged.
By the way, were you doing continuity testing with the TV plugged in also?