42" VIZO Television Will Not Power On

[MisterD]

Re: 42" VIZO Television Will Not Power On

Ok, thanks to you all for your support. I noticed in one of your photos a ground cable connected to a screw on your power supply board. Mine doesn't have that wire connected. Am I suppose to have it. Instead, my set is grounded at the power cord plug. Is that the equvalant? I will post the voltage readings as soon as my DMM arrives in the mail.
See these three photos.

That ground wire is my black negative probe to my volt meter, I loosened the screw and and slid the prob under it and tightened it back down, I used that method because I didn't have any alligator clip leads available.

[Cubone222]

Re: 42" VIZO Television Will Not Power On

That ground wire is my black negative probe to my volt meter, I loosened the screw and and slid the prob under it and tightened it back down, I used that method because I didn't have any alligator clip leads available.

OK, Thanks..

[MisterD]

Re: 42" VIZO Television Will Not Power On

Did you get that volt meter from Texas?

[Cubone222]

Re: 42" VIZO Television Will Not Power On

Did you get that volt meter from Texas?

It is still in transit through FedEx. It appears to be at my town just not delivered. I should have those voltages posted no later than Friday afternoon. You guys are a great help misterD, plain bill, Tom, and you other guys. I hope to get it working. 49cents is a real bargin when total investment was more.

[Cubone222]

Re: 42" VIZO Television Will Not Power On

OK, here are the voltage checks:

U2
AMC1117
F0734F
PIN1 1.44V
PIN2 2.32V
PIN3 5.09V

U7
AMC1117
F0734F
PIN1 0.02V
PIN2 1.27V
PIN3 3.28V

U8
AMC1117
F0734F
PIN1 2.00V
PIN2 3.23V
PIN3 5.11V

U9
K1117S15
745
PIN1 0.00V
PIN2 1.52V
PIN3 3.28V

U33
AMC1117
F0734F
PIN1 2.03V
PIN2 3.28V
PIN3 5.09V

I found three more scatered about the board:

U3
AZ7805T
-E1
746D61
PIN1 0.00V
PIN2 0.00V
PIN3 0.00V

U10
1084
0747AL
PIN1 1.35V
PIN2 2.6V
PIN3 5.08V

Q27
C5886
7x
PIN1 0.00V
PIN2 0.00V
PIN3 0.00V

OK, now what should I check.

[budm]

Re: 42" VIZO Television Will Not Power On

This is the way to figure out if the adjustable regulator is good or not:
Notes: 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.
See my Voltage calculator spreadsheet here, post #6:
https://www.badcaps.net/forum/showth...417#post273417

U2 (adjustable regulator) this one look bad, verify that you do have reading of 1.25V between pin1 and pin2 as I explained above. If pin 1 is 1.44, then the output (pin2) should be 1.25 + 1.44 = 2.69v
AMC1117
F0734F
PIN1 1.44V
PIN2 2.32V
PIN3 5.09V

U7 is OK, 1.25 +.02 = 1.27V
AMC1117
F0734F
PIN1 0.02V
PIN2 1.27V
PIN3 3.28V

U8 (adjustable) is OK. 1.25 + 2 = 3.25V, it is within 2%
AMC1117
F0734F
PIN1 2.00V
PIN2 3.23V
PIN3 5.11V

U9 is OK, it is a 1.5V fixed output regulator.
K1117S15
745
PIN1 0.00V
PIN2 1.52V
PIN3 3.28V

U33 (adjustable) is OK, 1.25 + 2.03 = 3.28V
AMC1117
F0734F
PIN1 2.03V
PIN2 3.28V
PIN3 5.09V

U10 (adjustable) is OK, 1.25 + 1.35 = 2.6V
1084
0747AL
PIN1 1.35V
PIN2 2.6V
PIN3 5.08V

U3, this one is 5V regulator 78xx series, it may be getting 0V input because of the bad regulator U2 not working right.
AZ7805T
-E1
746D61
PIN1 0.00V
PIN2 0.00V
PIN3 0.00V

1117 series LDO from DIGIKEY:

Adjustable:
http://www.digikey.com/product-detai...SCT-ND/1967218

1.5V fixed:
http://www.digikey.com/product-detai...SCT-ND/2121241

1.8V fixed:
http://www.digikey.com/product-detai...SCT-ND/1967216

2.5V fixed:
http://www.digikey.com/product-detai...SCT-ND/2121243

3.3V fixed:
http://www.digikey.com/product-detai...OSCT-ND/660708

[Cubone222]

Re: 42" VIZO Television Will Not Power On

OK budm. I will try and replace U2. I will replace U8 even though it is within tolarance. It seems to be getting bad although it is still OK. I hope that an 80W iron will be suffient. I have zero sodering skills. But youtube has got me somewhat prepaired. I will post back after I do said repair. You are very helpful. Thanks.

[MisterD]

Re: 42" VIZO Television Will Not Power On

OK budm. I will try and replace U2. I will replace U8 even though it is within tolarance. It seems to be getting bad although it is still OK. I hope that an 80W iron will be suffient. I have zero sodering skills. But youtube has got me somewhat prepaired. I will post back after I do said repair. You are very helpful. Thanks.

I use a 25 watt pencil soldering iron, also solder wick. you can try the heat/add solder and slide method but be very careful of surrounding components, like the little resistors, don't let the iron near them if possible. the solder wick or solder sucker method is ok but then the legs/pins of the regulator want to stick to the trace and when lifting it off you can pull up a trace with it. I hope all goes well for you.

[XmouseX]

Re: 42" VIZO Television Will Not Power On

I fix vizio's 80% of the time by replacing the Voltage regulators. Just test the input and outputs and you will find the faulty ones. U9 U2 are the most common for me.. Hope this helps.

[Cubone222]

Re: 42" VIZO Television Will Not Power On

I use a 25 watt pencil soldering iron, also solder wick. you can try the heat/add solder and slide method but be very careful of surrounding components, like the little resistors, don't let the iron near them if possible. the solder wick or solder sucker method is ok but then the legs/pins of the regulator want to stick to the trace and when lifting it off you can pull up a trace with it. I hope all goes well for you.

What size and type of solder do I need?

[MisterD]

Re: 42" VIZO Television Will Not Power On

[QUOTE=Cubone222;279200]What size and type of solder do I need?[/QUOTE


For electronics, it is traditionally a mix of tin and lead. Lead has a lower melting point than tin. I have used 60/40 for years with no issue.Try to find a small diameter solder.

"Heat the part not the solder"

[budm]

Re: 42" VIZO Television Will Not Power On

I cut the two legs off, no need to try to remove bad part as a whole.

[Cubone222]

Re: 42" VIZO Television Will Not Power On

I like that method budm, thanks misterD.

[Cubone222]

Re: 42" VIZO Television Will Not Power On

Sorry for the wait everyone. I just got all the supplys and will post back when I am finished with this operation. BTW, that game was cool.. Soldering may be too hard for me. I can't get the solder to stick and/or flow. A real pain! Any supporters? Guess not. I will bury the hachet and try again.. I think the solder I got is lead free junk!

[Cubone222]

Re: 42" VIZO Television Will Not Power On

I can't cut the three pins; I can't wick the solder. It's a nightmare!

[MisterD]

Re: 42" VIZO Television Will Not Power On

Do not use lead free solder!!!! use 60/40 electronic solder, always heat the part and let the part melt the solder, don't try to melt the solder and try to flow it onto the part...just get the legs of the part hot then melt the solder with the legs of the part. I wish I was there to help you cause I have a lot of soldering experience.
Keep your soldering iron tip clean by wiping with a wet sponge or use flux and wipe it off with a wet cloth.

[MisterD]

Re: 42" VIZO Television Will Not Power On

I can't cut the three pins; I can't wick the solder. It's a nightmare!

Do you have soldering paste? if so put some of it on the end of the wick you are about to use, lay the wick on the leg of the regulator, then put the soldering iron tip on top of the wick, it will draw only some of the solder out, cutting the pins or legs would be best but you need very small side cutters or dikes, then you could heat the tab last and grab the plastic body of the regulator with needle nose pliers or pry upward with a flat blad screwdriver while heating the part. be careful not to have the trace circuit stick and lift up with the part.

OR Actually this may be the best method.... Flux or Soldering paste is as must, use a lot and apply to all 3 pins and the tab of the regulator, heat all 3 pins and the tab keeping them hot and apply more solder to all of them keeping the solder melted, then slide the part away from where it's mounted. (Don't slide towards the small resistors, go the other way), you should then be able to remove it, then the last step is to clean the pads where the part was soldered on the circuit board with the wick, then solder in the new part by adding solder to one pad and one pin of the part, lay the part in place, heat only that one pin melting the solder, let it cool then solder each pin and the tab individually.

[MisterD]

Re: 42" VIZO Television Will Not Power On

About 2/3 of the way through this video Watch this guy remove U33 voltage regulator on a Vizio Mainboard similar to yours..it will work for you but you must use soldering paste also know as flux and apply it well to the pins and tab of the regulator, slide the part away from the small resistors just like he did.

http://www.youtube.com/watch?v=cNFzBJELFoU&feature=plcp

[Cubone222]

Re: 42" VIZO Television Will Not Power On

Yea, if only I could have misterd. It might be a cold solder but who cares. As of now the TV comes on. Amazing! It powered on. The light went from amber to white. It had a blue screen that said no signal. Is that normal?

[budm]

Re: 42" VIZO Television Will Not Power On

That is good, you just need to set the input to TV mode or DVD, or what ever video source you have. Good job getting it fixed.