vizio 42 gv421 no picture/sound

[TimT]

Tv has no picture or sound. the backlight works. I have to unplug the tv from outlet to turn it off. I have another Tv that does the same thing. is this a common problem? I would like to fix it but not sure were to start.

[MisterD]

Re: vizio 42 gv421 no picture/sound

Go to search this forum and type in Vizio, or Vizio GV421 and look at other posts, i myself fixed two vizios recently one was a bad voltage regulator on the main board. the other set had a defective T-CON Board. searching other threads/posts will give you a chance to see what other people have found. but most likely someone else will post some troubleshooting steps to help you diagnose it. Good Luck!

[TimT]

Re: vizio 42 gv421 no picture/sound

Thanks for the reply! search was not helpfull. I have a multimeter just not sure were to start

[TimT]

Re: vizio 42 gv421 no picture/sound

got the model#wrong should be gv42l. i did find some useful info on here

[TimT]

Re: vizio 42 gv421 no picture/sound

this dont look good?

[TimT]

Re: vizio 42 gv421 no picture/sound

new to this can someone tell me how to use a mulitmeter to test this?. im very new to this

[TimT]

Re: vizio 42 gv421 no picture/sound

chip with " green " is that normal? the chips are by Amtel 710 24c028n su18 and Atmel 716 24c028n s018 I cant find any information on these.

[Cubone222]

Re: vizio 42 gv421 no picture/sound

chip with " green " is that normal? the chips are by Amtel 710 24c028n su18 and Atmel 716 24c028n s018 I cant find any information on these.

I think those green and silver spots helped someone to denote pin 1 on the chip. They were replaced, or factory screwOP. You need better focused pictures. Front and back of the power supply board if possible. The whole main board. And a good picture of the whole back side of the TV so that the regular members can see how everything hooks up. I to had a bad voltage regulator on a 42" vizio. It sounds like a main board problem. But could be ccfls. Good luck.

[IamCanadian]

Re: vizio 42 gv421 no picture/sound

The Atmel chips are eeprom chips, Don't mess with them!

[TimT]

Re: vizio 42 gv421 no picture/sound

I wont mess with the chips! as i don't know what im doing I cant see anything wrong.. the caps " look " fine. here are more pictures.. I am having a hard time with my camera. so excuse the pictures.

[tom66]

Re: vizio 42 gv421 no picture/sound

On those connectors on the power supply, do you see a pin marked 5V (or 5VS, or 5VSTBY), and a pin marked ON/OFF, PSON or STBY?

[TimT]

Re: vizio 42 gv421 no picture/sound

I found 5vsb and pson see image. thank you

[tom66]

Re: vizio 42 gv421 no picture/sound

OK, what is the voltage at 5VSB and PSON when the TV is showing the ORANGE (standby) logo?

Then press the power button. Do the voltages change?

The main board and inverters should be plugged in for this test.

[TimT]

Re: vizio 42 gv421 no picture/sound

there 3.5.. funny i removed the ribbon cable to check then they were 3.0 then i put the cable back they were still 3.0 hopefully i am using the multimeter correctly. no change when i turen the tv off & on. better pictures of mainboard. is the powerboard ac and mainboard dc?

[tom66]

Re: vizio 42 gv421 no picture/sound

5VSB is just 3V? This is a problem. Can you just test a fresh AA battery just in case your meter isn't working right, you should get around 1.5-1.6V.

[TimT]

Re: vizio 42 gv421 no picture/sound

I tested a fresh AA Tested 1.5v retested the pins all were 3.5v ac except for pin " c " it was less then 1v 0.8 if i remember correctly.

[tom66]

Re: vizio 42 gv421 no picture/sound

Ah did you use DC volts or AC volts? You should use DC volts.

[budm]

Re: vizio 42 gv421 no picture/sound

"retested the pins all were 3.5v ac" AC?

[TimT]

Re: vizio 42 gv421 no picture/sound

used DC to check 1.5v AA battery. I used AC to check pins on power Board

[TimT]

Re: vizio 42 gv421 no picture/sound

I just tested it on the DC setting. I'll assume the power gets converted from AC to DC on the power board? 5VSB fluctuated between 1.44 to 1.55v PSON fluctuated between -0.08 to -0.16 and would jump to 0.78 to 0.86 when I turn the power on.