vizio gv47l amber logo no power on.

[Horty24]

Re: vizio gv47l amber logo no power on.

I need to test U1 IC 4953GM. What's the best way to do this with a DMM?
'

[Horty24]

Re: vizio gv47l amber logo no power on.

F1 rated @ 1.5A= .4OHMS, 5.13v at both ends.
F2 rated @ 1.5A= .4OHMS, 5.13v at both ends
F3 rated @ 3A. = .4OHMS. 0.63v at both ends.
Looks like failed fuse at F3?

I made a mistake a read wrong fuse layout I wrote fuse 1 and 3 backwards

F1 rated @ 3A = .4OHMs, 0.63 v
F3 rated @ 1.5A = .4OHMs , 5.13v

So I do have a bad fuse that feeds my low read regulators?

[budm]

Re: vizio gv47l amber logo no power on.

The fuse's resistances areOK, one of them will be fed by switched 12v, the other two are more likely to be fed by 5v. you can easily find out which is fed by 12v, or 5v by checking the resistance between the fuse and the power supply 12v and 5v pins.

[Horty24]

Re: vizio gv47l amber logo no power on.

From 5v to fuse
F1 = 0.0
F2 = 51.4
F3= 0.4

From 12v
All showed 0.0

[budm]

Re: vizio gv47l amber logo no power on.

So it looks like F1 and F3 are fed by 5V power supply. Th 12v pin should not be showing 0 Ohms to F1 or F3.
But it seems to me that F1 is showing "F1 rated @ 3A = .4OHMs, 0.63 v" which will be impossible since you are getting 5V at F3. You need to verify your measurement.

[dgelfuso]

Re: vizio gv47l amber logo no power on.

I need to test U1 IC 4953GM. What's the best way to do this with a DMM?
'

Horty, what was your fix for your GV47L? I believe mine has either a bad U11 (4953GM) or U8 (17-33L) because I only get 3.53VDC out of pins 5&6 of U11 going to pin 1 of U8. Any help would be very much appreciated.

David

[Horty24]

Re: vizio gv47l amber logo no power on.

Hi David, I could not find the problem with the main board. I even sent it out to a guy that fixes these boards and he couldn't even find the problem. I ended up Buying a board from eBay for 20$ and Walla. .. got my TV working. . Sorry.

[Horty24]

Re: vizio gv47l amber logo no power on.

But I think you're on the right track. .. u11 seems to be a culprit. Good luck.

[budm]

Re: vizio gv47l amber logo no power on.

On U11 (4953GM) you have 3.53VDC on the Drain pin (5/6). What do you have on the Source (S2) pin3?

[dgelfuso]

Re: vizio gv47l amber logo no power on.

On U11 (4953GM) you have 3.53VDC on the Drain pin (5/6). What do you have on the Source (S2) pin3?

When I apply power to the TV, S1 is 5.17VDC. When I turn on the set, it drops to 3.5VDC. You asked about S2, but I think that is for the #2 circuit with outputs on pins 7&8, correct?

[dgelfuso]

Re: vizio gv47l amber logo no power on.

Hi David, I could not find the problem with the main board. I even sent it out to a guy that fixes these boards and he couldn't even find the problem. I ended up Buying a board from eBay for 20$ and Walla. .. got my TV working. . Sorry.

Thanks, and how did you find a working board for $20? If I could, I would simply do that and stop trying the DIY way.

[budm]

Re: vizio gv47l amber logo no power on.

"I only get 3.53VDC out of pins 5&6"
S2 is the Source pin of the MOSFET #2, PIN 5 and 6 are the Drain pin of MOSFET #2.
So right now you have about 3.5V at the Drain of MOSFET #2, S2 is the input for the B+, when MOSFET #2 is turn on, the voltage will pass through to the D2 (PIN 5/6). MOSFET is being used as a switch so we need to find out if S2 also has about 3.5V, if it does, then the MOSFET is OK.
S1 is for MOSFET #1, pin 7and 8 are the Drain (D1) pin of MOSFET #1.
When the voltage drops a lot, it means it is being loaded down too much or the 5V power supply is too weak to handle the load.

[dgelfuso]

Re: vizio gv47l amber logo no power on.

"I only get 3.53VDC out of pins 5&6"
S2 is the Source pin of the MOSFET #2, PIN 5 and 6 are the Drain pin of MOSFET #2.
So right now you have about 3.5V at the Drain of MOSFET #2, S2 is the input for the B+, when MOSFET #2 is turn on, the voltage will pass through to the D2 (PIN 5/6). MOSFET is being used as a switch so we need to find out if S2 also has about 3.5V, if it does, then the MOSFET is OK.
S1 is for MOSFET #1, pin 7and 8 are the Drain (D1) pin of MOSFET #1.
When the voltage drops a lot, it means it is being loaded down too much or the 5V power supply is too weak to handle the load.

I think I might have the pin numbers wrong, so hopefully this clears it up:

With power applied and the TV not powered on (all values are VDC):
S1:5.17 D1:0.5
G1:4.98 D1:0.5
S2:3.32 D2:0.100 and climbed while holding probe on the pin
G2:4.98 D2:0.100 and climbed while holding probe on the pin

With power applied and TV power turned on:
S1:3.58 D1:3.53
G1:0.060 D1:3.53
S2:3.32 D2:3.32
G2:0.060 D2:3.32

[budm]

Re: vizio gv47l amber logo no power on.

OK, the MOSFETs are OK, they are switching as it should, the problem is the 5.17V power supply line, it is not holding at 5V.
You need to find out if this 5V feeding the S1 (MOSFET #1) is from the 5VSTBY or it is generated from some where else.
The voltages are being fed into the Source pins and go out on the Drain pins.

[Shane711]

Re: vizio gv47l amber logo no power on.

So I got 2 of these TVs ( Vizio GV47L ) The first one I got about 2 weeks ago and it was the fuse on the main board marked F3 (1.5A Fast blow) It was hard to believe it was that simple.

The second one I got today and I was like "I know what it is!", but I was wrong so I figured it had to be a voltage regulator and I started testing them. I was suspecting U5 but I was not sure. Then I came on here and saw budm's formula for testing the regulators and I decided to replace U5 and the TV turned on. Awesome! The first time it turned on nothing was working like the volume and source but I unplugged it and turned it back on and it decided to work. So I am happy

OK, now when U5 was bad pin 3 was about .350 volts and after I replaced it, it was like .750 volts. The output now is 1.90 to 2v so now the math adds up.

So budm, if pin 3 reads 0.00v does that always mean it is a fixed regulator?