32" Vizio Fixed Regulator. How do I/Can I adjust

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

now without U33 attached it reads 181 ohms for both resistors. and instead of 6 on bottom one it is now 3 ohms. I also resoldered first with a much cleaner job making sure they were not touching. Didnt work so hopefully this makes better sense to you. Thanks Budm for everything so far.

[selldoor]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Now one more time? Do what?

Measure the resistors?

Also that blue/black cap connected to u7 looks to have a brown mark on the side is it ok or is it leaky - bad caps adjacent to regulators can distort the voltages.

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

All caps look fine. Im not sure what your seeing.

R30 - 181 ohms

R32- 181 ohms

(without U33 attached to the board)

[budm]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

If that is the correct reading on those two resistors, the output will be 2.5V

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

So i need a new regulator?

[tom66]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

What is the voltage between OUT and ADJ?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Out (center)= 2.02
ADJ (left pin)=.01

so 2.01?

[tom66]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Yes, the regulator is very bad. It should be 1.25V. Where did you get it; is it definitely an adjustable regulator?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

digikey... well tell me is this even the right one? I thought it was but maybe not.

http://www.digikey.com/product-detai...29-1-ND/586229

[tom66]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

It looks correct, seems very odd!! What is the part number on it?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

The original number on the old regulator said AMC1117

[tom66]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

What about on the new one?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Ld1117astr

[tom66]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Very odd. Have you got a second part you can try? It does not make sense. Is there no shor between Vin and ADJ, or Vin and Vout?

[budm]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

If the two resistors having the same value, even with the good regulator, the out put will still be only 2.5V. That U33 is set to have output of 3.3V, its output is also feed U7. So we need to concentrate on the area around U33 to see if there are shorted path somewhere, we can easily change the two resistor to make U33 put out 3.3v, but we need to look around the area first.

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Yea im afraid I may have ruined the board after taking the regulator out so many times. Its got some black burn marks around where it was. Might be getting a new board unless its fixable

[budm]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

By any chance that you also bought the 1117-3.3?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

I just bought one from the link above. Im probably gonna buy a few more should I try a different one?

[budm]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

If it is fixed 3.3V regulator, then you can use it by having pin 1 connected to ground, the middle pin will go to same point (same place as original), the third pin will go to the input (same place as original). You will not need those two resistors since we will use fixed output regulator which does not need external resistor. I do not know why Vizio does not use the fixed regulator in the first place for the 3.3V.
By the way, the input voltage to this U33 is 5V, right?

[Loozer]

Re: 32" Vizio Fixed Regulator. How do I/Can I adjust

Yes 5 V. Im gonna do that then. Sounds easier