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

[Loozer]

So i just replaced a bad regulator on a Vizio i have. It powered on with backlight but no sound or no image whatsoever. Also it couldnt be turned off once turned on unless you unplug the power cable. Well I recieved and new regulator and replaced it and when i turned it on i had an image of (channel 37) and some vertical blue lines on the screen. It also turned off from the side inputs which was good but when i check the voltages on the new regulator the adjust pin reads .01 V. I know this is wrong and there is a few resistors that i dont think i touched but maybe its possible i unsoldered one because one of them reads 2.02 V and the other reads nothing. Not sure because i didnt test them before (stupid) Now its back to the old symptoms tho and i get no picture/wont turn off. My question is can i adjust the last pin back up around 1-2 V where it should be or did i blow this new regulator already? Any help would be appreciated thank you.

[selldoor]

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

You should test the resistors off board meter on ohms scale to cover the expected result. Do you mean new regulator in the last sentence - perhaps edit it.


This might help
https://www.badcaps.net/forum/showpo...2&postcount=80

[tom66]

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

Voltage from OUT to ADJ should be 1.25V.

[Loozer]

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

Thanks.
u33 reads:
Yes pin 1 reads 5.07 and pin 2 reads 2.02. Pin 3 is reading .01
which would mean its bad right. I checked U7 too which is connected to U33(the one i replaced)
u7 reads:
pin 1- 2.01 pin 2 - .97 pin 3 - .02

i will check the resistors tonight when i get off work. But appreciate anything you can add to help.

[Loozer]

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

You should test the resistors off board meter on ohms scale to cover the expected result.
This might help
https://www.badcaps.net/forum/showpo...2&postcount=80

Now one more time? Do what?

[Loozer]

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

My question is can you manually adjust the 3rd pin on U33? i know the voltage is wrong but i literally just got it in the mail today. If not im just goin to order 2 new regulators and replace both U33 and U7 and hope for the best.

[Loozer]

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

Voltage from OUT to ADJ should be 1.25V.

i know thats what it should be. The new regulator however is reading the same as the old one. Im wondering if you can adjust it or if it sounds to you like its just another faulty regulator. Thanks again tom

[budm]

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

The voltage on pin out looks confused: It looks like you count it as, with big tab up, pin1 as the right most pin.
I look at it this way:
If we are looking at the regulator with the Big tab up (the big tab is tied internally to the center pin).
Adjustable regulator will have two resistors attached to it, one resistor (Rfb) is between pin1 and pin2, another resistor (Rg) is between pin1 and ground. Pin3 is an input pin.
The voltage between the Adjust pin (left pin) and the center pin (Pin2, output) will always be 1.25V +/- 2% (this is the precision voltage reference), if it is not, it is bad.
To figure out what the output voltage should be: measure the voltage between pin 1 and ground and add 1.25V to that number, that is the output voltage on pin 2 but you have to make sure you do have 1.25 between pin 1 and 2 as noted above
What is the model of this VIZIO?

[Loozer]

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

Yeah both regulators are bad then. Ill just buy like 10 this time in case i run into this problem again. They were only 50 cent each.

Model No: VX32L HDTV10A

[budm]

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

You may have damage the resistors or thy came off during de-soldering. Do you have good clear pictures of these two regulators.
I just upload the calculator for the LDO in post 8

[budm]

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

I look at SHOPJIMMY and see that both regulators have two resistor close by. Do you know what the output voltage should be? I can try searching the forum for U7, U33 but that may take times.
If the resistors are still there, you can give me the value then I tell if they are correct or not using my calculator.
Follow-up: I found the value:
U33 = 3.3v
U7 = 1.25V

[budm]

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

Thanks.
u33 reads:
Yes pin 1 reads 5.07 and pin 2 reads 2.02. Pin 3 is reading .01
which would mean its bad right. I checked U7 too which is connected to U33(the one i replaced)
u7 reads:
pin 1- 2.01 pin 2 - .97 pin 3 - .02

i will check the resistors tonight when i get off work. But appreciate anything you can add to help.

So from the reading above, the U7 is reading wrong because U33 output is too low for the U7 to work. So we just need to fix U33 section.

[Loozer]

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

yeah i only have a pic of from before until tomorrow.

alright i set the multimeter to 2000 ohms and:

R30 read: 354

R32 read: 1 (thats what it reads when not even connected to anything, So looks like this is bad or damaged)

CB21 actually made the meter dim out and displayed nothing. Not sure what that means

I may be looking for a new board as it looks. I may have burned something when taking out the original. It doesnt look pretty

[budm]

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

Which one of the resistor has one end connected to ground?

[budm]

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

I search the forum and it looks like R30 is connected between the ADJ pin and Ground, the R32 is connected between the ADJ pin and the Output pin. So you must have solder bridge between ADJ and the output pin.

[Loozer]

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

Alright i didnt realize there were 2 readings for them.

R30: Top of pin(in pic) 354
bottom 6

R32 top: 351
bottom: 1

[Loozer]

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

Solder bridge? So should i desolder and solder again with a smaller bead?

[budm]

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

What do you mean by bottom 6 and bottom 1?
Is the reading across R30 = 354 Ohms
and the reading across R32 = 351 Ohms?

[Loozer]

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

yes I dont know when i touch the top(in pic) or piece closest to regulators they read 354 ohms and 351 ohms. on the opposite side one doesnt read anything and one reads 6. (on 2000 ohms setting) its very possible that there may be a solder bridge tho. im not the most precise yet haha

[budm]

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

I think you should remove U33, then take the resistance reading across each resistors for me.
It is 12'O clock, so I am going to bed. We will continue tomorrow evening, good night.