Vizio gv47l fhdtv10a

[mmoore5553]

Just wanted to say first off thank you everyone for helping me on some of those tv's. I got another one for free. It is a vizio gv47l fhdtv10a.

I have done some troubleshooting already and look around the forum. I plug it in and hear the relay click . So i know some voltages are there. I checked and i have the 5 volt standby. I have checked and see the 12v to the regulator and then five volts out of it.

I have narrowed it down I believe but not 100 percent sure. I do not have a back light. Sometimes when i turn the TV on and hit the power it light up and logo goes to white. Every now and then it does not even do that but when i unplug you hear the relay click all the time.

TV comes on and buttons light up amber and logo goes white. I have check voltages on some transistors. I have listed them here. I think one of the transistors is bad.

If I am wrong please let me know or if i should check some other area's.

I think it is U5 which is amc1117

I messaged the voltage from the bottom leg up to the top.

Here is some voltages on the regulator -

U5
pin 1 --- .48
pin 2 --- 1.34
pin 3 --- 3.3

u9

pin 1 --- .0
pin 2 --- 1.8
pin 3 --- 3.3

u10

pin 1 --- .0
pin 2 --- 1.8
pin 3 --- 3.3

[mmoore5553]

Re: Vizio gv47l fhdtv10a

If i need to upload better pictures please let me know. Here is the picture of the problem child and i label how i measured the pins.

the chip is amc1117

I just am getting way to low of voltage on pins 1 and 2 . Or I should say I think I am . Let's see what the experts say.

[budm]

Re: Vizio gv47l fhdtv10a

U5
pin 1 --- .48
pin 2 --- 1.34
pin 3 --- 3.3

Pin 2 output should be = 1.25Vref + 0.48V = 1.73V, so yes, that voltage is wrong for this ADJ. x1117.

[mmoore5553]

Re: Vizio gv47l fhdtv10a

Just so i can learn some more. How did you get the 1.25 ? I just assumed since pin 3 was 3.3 that the other pin should match the other two transistors to have at least close to 1.8.

Thanks for the teaching lesson.

[cliff_hootarski]

Re: Vizio gv47l fhdtv10a

Did you check all three fuses on the top right of the board? These boards have a bad habit of blowing one of those fuses.

[budm]

Re: Vizio gv47l fhdtv10a

The 1.25V is the Vref inside the Adjustable 1117 type, pin 1 and 2 will always have 1.25V +/- 2% between the two pins. The output on pin 2 will always be = 1.25V + to what you read on pin 1.
You can tell if it is adjustable by looking at pin one, there will be one resistors between pin 1 and pin 2, and another resistor between pin 1 and circuit Ground.
This is the calculator for figuring out the value of the resistors.
https://www.badcaps.net/forum/showth...999#post300999

[mmoore5553]

Re: Vizio gv47l fhdtv10a

Cliff- Yes , I did check the fuses. I was hoping it was that easy.

Budm - Thank you so much on the exclamation. Just still loss. I am trying to figure out how you new 1.25 v . Was that on a schemative or because 1117. I can not understand how you got the 1.25. i know 1.7 and 2 percent of that puts us around 1.5. Sorry for the newbie but trying to wrap my head around how you come to that. Yes , I seen the resistors to ground. Or is it by just the datasheet min at 1.25 .

[budm]

Re: Vizio gv47l fhdtv10a

Some of them can be as tight as 1%, 1.238V on the low end, and 1.263 on the high end.
The spec for AP1117 has Vref 2% for the Adjustable, and also 2% for the output voltage of the fixed regulator.

[jwillifixit]

Re: Vizio gv47l fhdtv10a

Wow... I got one for free today and have exactly the same issue. What did you do to "fix" yours? Did you replace AMC 1115 chip?

[budm]

Re: Vizio gv47l fhdtv10a

Wow... I got one for free today and have exactly the same issue. What did you do to "fix" yours? Did you replace AMC 1115 chip?

Do you mean 1117 regulator IC?
Did you check the regulator Voltages, fuses, control signals, etc?

[ivtec]

Re: Vizio gv47l fhdtv10a

https://www.youtube.com/watch?v=qC9FEZ78-qM


I have fixed one of this for a friend ;see the whole video

https://www.badcaps.net/forum/showthread.php?t=52743

https://www.youtube.com/watch?v=qC9FEZ78-qM

[jwillifixit]

Re: Vizio gv47l fhdtv10a

Budm - yes I did mean 117 regulator IC. I did start to look at the voltages and some were clearly not right. now after seeing Ivtec's video I'll check those fuses and post the results of all this evening. Guys I've not done this sort of diagnostics and repair before and am really loving this!!! Thanks so much for what you do and for supporting us noobs as we try to learn.

[jwillifixit]

Re: Vizio gv47l fhdtv10a

Continuity check on F1, F2, F3 was good.
I really don't know how to check the amp draw using my meter (pic attached) but here's what I found on all the voltage regulators that I could locate.
U5 = 3.26 In, 3.0 Out, 0.01 Adj
U10 = 3.26, 1.80, 0.01
U9 = 3.26, 1.80, 0.01
U8 = 4.98, 3.26, 0.01
U6 = 5.06, 3.26, 0.01
U4 = 5.06, 3.26, 0.01
U18 = 3.26, 1.49, 0.26
U7 = 3.26, 1.80, 0.01
DU2 = 4.98, 3.26, 0.01
DU3 = 4.99, 2.50, 0.01
DU4 = 3.28, 1.24, 0.01
DU1 = 5.00, 0.01, 11.64

How do I further check the fuses using this meter.

[budm]

Re: Vizio gv47l fhdtv10a

"U5 = 3.26 In, 3.0 Out, 0.01 Adj:" This does not look right, the difference between the Vin and Vout is only 0.26V, typical for regulation is between 1.1~1.2V. It is bad to me.
What is the P/N as printed on that IC?
Any good closed up pictures of the U5?

[dick_barton]

Re: Vizio gv47l fhdtv10a

Continuity check on F1, F2, F3 was good.
How do I further check the fuses using this meter.

Turn the dial on your meter to --!>-- position. Place probes either side of diode and take reading, then reverse leads and read again. Good diodes have a reading in one direction say 0.3 - 0.7 and OL (open) the other direction.
If there is a reading in both directions then lift one end of the diode off the board and test again.

[jwillifixit]

Re: Vizio gv47l fhdtv10a

U5 correction:
3.26 In, 3.0 Out, 1.08 Adj

I confirmed the Out several times.

Part number is:
AMC1117
F0706J

Close up of U5/U10/U9 attached.

Still think replacing that AMC1117 at U5 is a good starting point?


I'm still not getting how to check out those fuses...
With the unit off I get continuity but how do I check the current draw?

Thanks again

[jwillifixit]

Re: Vizio gv47l fhdtv10a

I forgot to say that i "think" i'm getting
F1 = 0.221 Amps
F2 = 0.049 Amps
F3 = 0.079 Amps

U5 correction:

I'm still not getting how to check out those fuses...
With the unit off I get continuity but how do I check the current draw?

Here's a close up of them.

Thanks again

[dick_barton]

Re: Vizio gv47l fhdtv10a

I'm still not getting how to check out those fuses...
With the unit off I get continuity but how do I check the current draw?
Thanks again

You don't need to check the current to see if the fuse is OK. A continuity test with your meter on ohms should show short circuit 0.00 ohms (or close enough ignoring the resistance of the meter leads.
If the fuses are OK then I don't know why you want to know the current through them.

You would need to lift the fuse, off the solder pads and set your meter to Amps and place your meter lead across the two pads it was lifted from.

[jwillifixit]

Re: Vizio gv47l fhdtv10a

dick_barton... thanks for the response and I think I understand you. My question about the current draw under load was because of a post a few up from ivtec who has a link to a youtube diagnostic video on this same TV. Have a look - starting about about 1:20 he's talking about checking the current draw on the bad "open" fuse at F1.

I'm going to get some parts on order from Digikey and figure since they are not expensive I'll pick up the fuse as well even though it has continuity. At this point all I'm looking at replacing on this board is the IC at U5
AMC1117
F0706J

https://www.youtube.com/watch?v=qC9FEZ78-qM

[dick_barton]

Re: Vizio gv47l fhdtv10a

The fuse he is checking the current on, is open circuit i.e. blown, so it would be identical to having no fuse at that position and he's measuring the current between the two pads that the fuse is soldered to to establish how much current was flowing and if it was more than the fuse rating that blew.

If your fuse has continuity when checked using your meter on ohms and of course with the set off, then there's no point doing this?