Vizio SV420XVT1A no sound

[sawickipeter]

Hi, I just got a Vizio SV420XVT1A from my sister in law. However, the unit has no sound. I tried the cable input as well as HDMI and reset all video and audio settings but still no audio. She said that she sometimes had audio for about 30 minutes and it would quit. Was at random. Currently I can't get any audio out. I have tried the unplug and reset options online already. Anyone have any pointers at what to look at on either the main board or the audio board?

[Andrew F. Ali]

Re: Vizio SV420XVT1A no sound

Have you tested the speakers to see if they are good? Try a head phones to see if the audio circuit is really faulty.

[sawickipeter]

Re: Vizio SV420XVT1A no sound

I checked the speakers with a function generator and they do work.
I also found the service manual for this unit on another thread and performed the DC-DC Converter check, which all checked good. There is also a "Trouble of Speaker Out" section which I went through. On the TX BD/Tx Card I only had the issue of 3.3V on Pin2 of JC2 missing. It shows 0V only. I also checked pin 1 and 3 on JC2 and those show 0V as well while plugged in. However, when I disconnect that cable, I still get 0V on pin 2 but pins 1 and 3 show 8V.

Unfortunately I do not have the schematic for this unit so not sure where that 3.3V is being generated at for that pin. I did see the 3.3V come out on the main board on J14/J19 on pin 2 which goes into the audio board and I see it there as well but what happens throughout the audio board I have no idea.

[Andrew F. Ali]

Re: Vizio SV420XVT1A no sound

You could measure the resistance of the speaker coil; by putting your DMM on 200 and observe what the reading across the coil. Or you can use a 1.5v battery across the speaker terminals and see if the cone move and hear a pop at the same time. All this is done with the speaker disconnected, of course.

[R_J]

Re: Vizio SV420XVT1A no sound

I just checked shopjimmy for this model and it shows a seperate board for audio . Maybe post a couple good quality pictures or go to shopjimmy's site and see which boards are used in your tv.

[sawickipeter]

Re: Vizio SV420XVT1A no sound

You could measure the resistance of the speaker coil; by putting your DMM on 200 and observe what the reading across the coil. Or you can use a 1.5v battery across the speaker terminals and see if the cone move and hear a pop at the same time. All this is done with the speaker disconnected, of course.

The speakers do produce a pop as a result of being energized when the TV turns on. I also ran the speaker wires through a sweep function generate and they produce sounds, so those seem to be ok. I am not quite certain if my problem may be on the main board or the audio board. On the audio board, I am not getting the 3.3V to the Tx Board, however, not sure if that 3.3V is also missing on other components of the audio board without a schematic that may be part of the output drive for the speaker system.

[budm]

Re: Vizio SV420XVT1A no sound

Can we at least see the pictures of the whole backside of the TV showing all the boards?
Dose it have RCA Audio line out jacks (Red and White jacks) that you can connected to powered speakers to see if you do get sound or not?
Does it have headphone jack?

[sawickipeter]

Re: Vizio SV420XVT1A no sound

Attached are pictures of the boards. The square board is the audio board. The rectangular is the main board. This TV has RCA audio output jacks but I do not have any device i can plug into it to test. Unfortunately there are no headphone audio jacks on this unit either.

[PeterKiryluk]

Re: Vizio SV420XVT1A no sound

SOLUTION, to anyone reading with this problem. The main board may have a bad 630UF capacitor its the biggest one one the board. Set the analog output to variable on the tv menu. On the main board u will notice a 4 pin output on the audio out section. Take the cord running to the sd card, that is the same size, (it runs to the separate audio board) Hook that cable to the 4 pin audio test port next above the audio out. The sound will now work. You will loose whatever the SD thing does but that looks useless anyway so i dont it will be missed. The sound will now work.

[PeterKiryluk]

Re: Vizio SV420XVT1A no sound

Correction NOT ALL THE CONNECTIONS ONLY THE BROWN WIRE. out of the 4

[T33]

Re: Vizio SV420XVT1A no sound

SOLUTION, to anyone reading with this problem. The main board may have a bad 630UF capacitor its the biggest one one the board. Set the analog output to variable on the tv menu. On the main board u will notice a 4 pin output on the audio out section. Take the cord running to the sd card, that is the same size, (it runs to the separate audio board) Hook that cable to the 4 pin audio test port next above the audio out. The sound will now work. You will loose whatever the SD thing does but that looks useless anyway so i dont it will be missed. The sound will now work.

hi, i just joined and have seen the pics. i dont have a background in this and yes i know i dont have any business insid the tv but......it's all discontinued now so i need to fix it. now then what/where is the sd card? what/where is the test port? maybe point these out on the pic? thanks