Vizio VX32L turns on with backlight, no video or sound

[Ayelix]

Hello,
I have the same problem as described in the thread here. My Vizio VX32L turns on with the power button, the light changes from amber to white and the backlight comes on, but there is no sound or video (only black screen). I have read the thread linked above and followed the troubleshooting for DC-DC converters in the VW32L manual (here) with no success. The VW32L manual is the most similar to the VX32L that I could find, in fact I found no differences in component names or values while troubleshooting. I have tested all of the components recommended in the manual and all seem to be working fine. Any recommendations of what I should try next?
Thanks

[cadiman]

Re: Vizio VX32L turns on with backlight, no video or sound

The problem is not the power supply with these. The problem is on the mainboard.
Look at U-9 (amc1117) 3.3v It will be low(2.2)or so. This is the same on vx32 and 37.

The tv will turn on the backlight, but nothing else.

Also you can use the vx32 mainboard on the vx37 tv. That was how I found the problem and reading posts here always helps too.

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

When I said I followed the troubleshooting for the DC-DC converters, I meant those on the mainboard. I also read to check U9 in another thread and it is at 3.3V.

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

Also working on VX32L same symptoms. I noticed at power up the blue led on inverter board has short delay then turns on, off, on ,then fades off slowly.Once the led turns on, both inverter boards make buzzing sounds, loud enough to hear ,but hard to tell where it was coming from. Have not checked anything on these boards yet.

I also checked voltages on LDO reg. I have 2 readings because the voltage changed from power up(1st reading) to when the inverter led came on(2nd reading).
LDO ... V in (1-3) ... V out (1-2) ... (2-3)

U33 ... 3.15/3.85 ... .84/.18 ... 2.88/3.01
U9 ... 2.03/1.89 ... 1.02/.83 ... 1.04/1.06
U7 ... 2.23/2.05 ... 1.16/.99 ... 1.04/1.05
U8,U2,U4 .. 3.08 ... . 1.24 ... .. 1.84

Mainboard 3632-0102-0150(4B) LDO reg all above marked AMC1117 F0646J

Also U10 measured 3.01
That is as far as I am. I had to come in and warm up, it's 18 degrees in my garage.

[cadiman]

Re: Vizio VX32L turns on with backlight, no video or sound

When the inverter board first powers up you will see the blue led light and then it will go out this is normal. should not go off and on then off

You will hear them buzz a bit like a shop light ballast. If they are really loud the ccfls are going bad.

Make sure you have the 5v standby from power supply. There are 2 small fuses soldered to the board near the power supply plug at the main board. Check these with your meter. I think one is the 5v standby and the other is the 12v after the supply is turned on.

If you really get into this thing I can take the cover off of mine and get voltages for you.

When the power button is pushed and the backlights are on you should have 12v going to the main board.(check U-3) it`s in front of the audio output IC and just under the part number. That might be the regulator of some sort should be 12v there.

good luck!

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

I have checked all of my DC-DC converter voltages and the power supply input on the main board. I can check them all again and record my readings to compare to someone else's readings if that would help me or 1simtime.

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

Both fuses on main and each fuse on inverter boards are good .
At the P.S. is 5.18v standby. powered up 5.18v , 12.00v, 24.2v and 24.2v.
U3 (7805ct) tab(gnd) to pin 1(in) is 11.9v and tab to pin 2(out) is 5.0v.
All caps on p.s. mainboard and both inverter boards appear good .I do not have an esr meter but I would like to get one.
From another vizio post I got a Digi- Key # 497-1229-1-nd for the amc1117 F0646J . The voltages I showed on my last post for U33,U9and U7 do not appear to be normal . Anything else to check before I order? Thanks

[cadiman]

Re: Vizio VX32L turns on with backlight, no video or sound

I have the cover off and I have a list of v-in and v-out for amc1117.
u33 5v in 3.2 out
u2 5v in 3.2 out
u4 5v in 3.2 out
u8 5v in 3.2 out

u7 3.2v in 1.25 out
u9 3.2v in 1.50 out

u8 has 5v in 3.2v out at all times

also check for 4 or 5v at small transisters at button control plug-in at upper left of board. (when button pushed).

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

You guys on this site are the best ! Willing to take your TV apart to get voltage readings to help out. Thanks cadiman !!!

I didn't get the same readings as you. I used pins 1-3 for in ..1-2 for out..2-3? This was how some one from another Vizio post got their readings.(pasted below)
I understand the mainboard is from a different model so the voltages I got may not be the same .

kingofcoins's
Default Re: Vizio VW42LFHDTV10...Brother Mikes TV...mainboard woes
I'm still a bit over my head on this, so when you get a chance...
New point... does the fact I get no backlight action at all mean I need to address
it separately, or is it likely the mainboard trouble keeping them off?

I not sure I took enough info on the last post so here is all the LDO regulator readings
for Vin (1-3) and Vout (1-2) and pin 2 ? (2-3):
U2.... 3.0VDC 1.2V 1.8V
U7.... 3.4 1.1 2.25
U8.... 3.1 1.2 1.85
U9.... 3.3 1.5 1.75
U33... 3.0 1.2 1.8
4 of these are AMC1117 F0646J U9 is a K1117S15 612

cadiman ..What did you use for gnd and pins for in and out so I can compare my readings? THANKS

[cadiman]

Re: Vizio VX32L turns on with backlight, no video or sound

U9 can be replaced with an amc1117. All of these are the same on the vx 32 board.

The vx37 had a k1117s15 same as the amc1117 I think the 1117 is the clue here.
You can use tv frame on this one (what the board is screwed to).

As you look at the amc1117 (the rca plugs, audio and video inputs facing you) the upper pin is v in, the middle pin is v out and the lower pin is adj. or possibly ground. these are soldered at the top of the ic depending on how you are looking at it.

In your case the top is on your left and the 3 pins are on the right.
The top is also center pin or v out. check here so you don`t short the output to the input.

You should have 5v going into all of these except for u7 and u9.

u8 should have 5v in and 3.2 out all the time. I think you should check here first with tv plugged in and tv turned off

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

Using board gnd instead of pin 1 made the difference.(post#4 used pin1 for gnd and post #9 measurements were from a post with a different model # I used as reference.

here is what I got using board gnd
LDO...pin 3........pin 2....
U33... 5.13v in . 2.05v out
U7.... 2.05v in . 1.00v out
U9.... 2.05v in . 1.0ov out
These 3 look low compared to your readings

U2,U4,U8 appear normal with 5v in and 3.2v out
U8 had 5v in and 3.2v out with tv off

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

1simtime, according to cadiman and the vw32l service manual, U33 is supposed to be at 3.3V and U7 is supposed to be at 1.2V. U9 however is not mentioned in the service manual. It looks like U33 may be the problem as it may be providing the input for U7 and U9 which is supposed to be 3.3V. This is just a guess though. Someone with knowledge of these components could confirm this.

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

Ayelix, are you getting anywhere with your VX32?

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

I have not touched it since I made the post. Tomorrow I will take readings of all the DC-DC converters on the board and record my results.

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

I took all my readings today. It seems that the inputs for almost all the 1117 converters are low, ~3V instead of 5V. I recorded the standby (SB) in and out voltages and the power on (ON) in and out voltages. Pin 1 was used as ground, the larger tab (connected to pin 2) was used for out readings, and pin 3 was used for in readings.

Component  SB out  SB in  ON out	ON in
U10     0    0    1.25   3.62
U7      0    0    1.24   3.29
U9      0    0    1.24   3.04
U33     0    0    1.24   1.94
U8      1.24   3.04   1.24	2.98
U2      0.04   0.19   1.25	2.93  *See below
U4      0    0    1.24   2.97
U3      0         11.93      Using P2 GND, P1 V+
U3      0         5.02       Using P2 GND, P3 V+

I think these readings are different than what I saw a couple days ago. I think it may be because I was using the board ground (a mounting screw) during my readings instead of pin 1 of each converter.
U2 is interesting. It reads very low on standby, but as long as the reset button is held down it goes to ~3V in and ~1.24V out. Once the reset button is released it goes back to the very low input and output. I don't really know what to make of all this!
I'm going to go check all of the power connections again and I will edit this post to add those readings.

[PlainBill]

Re: Vizio VX32L turns on with backlight, no video or sound

I took all my readings today. It seems that the inputs for almost all the 1117 converters are low, ~3V instead of 5V. I recorded the standby (SB) in and out voltages and the power on (ON) in and out voltages. Pin 1 was used as ground, the larger tab (connected to pin 2) was used for out readings, and pin 3 was used for in readings.

Component  SB out  SB in  ON out	ON in
U10     0    0    1.25   3.62
U7      0    0    1.24   3.29
U9      0    0    1.24   3.04
U33     0    0    1.24   1.94
U8      1.24   3.04   1.24	2.98
U2      0.04   0.19   1.25	2.93  *See below
U4      0    0    1.24   2.97
U3      0         11.93      Using P2 GND, P1 V+
U3      0         5.02       Using P2 GND, P3 V+

I think these readings are different than what I saw a couple days ago. I think it may be because I was using the board ground (a mounting screw) during my readings instead of pin 1 of each converter.
U2 is interesting. It reads very low on standby, but as long as the reset button is held down it goes to ~3V in and ~1.24V out. Once the reset button is released it goes back to the very low input and output. I don't really know what to make of all this!
I'm going to go check all of the power connections again and I will edit this post to add those readings.

One point to consider, the AMC, AS, LM, etc 1117 regulators come in variable (AS1117) and fixed (AS1117-33; AS1117-25; etc) versions. On a fixed output version, pin 1 is at Gnd. On a variable output version pin 1 is the Adj input, and will be at some voltage above gnd. As you noticed, it is important to choose the Ground point for your measurements carefully.

PlainBill

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

Should I be using the board ground with the adjustable regulators and pin 1 for the fixed regulators? If that is the case then all readings should just be taken using board ground right?
Thanks for the help.

[Ayelix]

Re: Vizio VX32L turns on with backlight, no video or sound

Here are my readings using the board ground instead of pin 1 of the regulators. Nothing looks wrong here . Also, it all matches the correct values in the DC-DC troubleshooting section of the VW32L service manual.

Component	SB out	SB in	ON out	ON in	
U10		0	0	2.62	4.99	
U7		0	0	1.24	3.29	
U9		0	0	1.49	3.29	
U33		0	0	3.3	5	
U8		3.3	5	3.3	5.04	
U2		0.12	0	3.33	5	
U4		0	0	3.28	5	
U3 		0		11.93		Pin 1
U3 		0		5.02		Pin 3
U1 		0	?	5	?	Pins 1,3,5,6,7,8
U6 		0	?	1.6	?	Pins 5,6

J1:
   Pin 1      PWR ON (about 3.3V? Mine's 1.7V)
   Pins 2,3,4,5   12V ON
   Pins 6,7,8    GND
   Pins 9,10,11   5V SB

F1: 12V ON
F2: 5V SB

[cadiman]

Re: Vizio VX32L turns on with backlight, no video or sound

I would go after u33 1simtime. my readings are from A GOOD WORKING BOARD ON A WORKING TV THAT I AM WATCHING A MOVIE ON.

1)As long as you get the same readings I have or not it will get you headed in the right direction, if we are lucky.

2)When an amc1117 fails I am pretty sure they go low.

3)Check with Plainbill

[1simtime]

Re: Vizio VX32L turns on with backlight, no video or sound

I plan to order from Digi- Key # 497-1229-1-nd for the amc1117 F0646J
I will post back when I get it replaced Thanks

I think Ayelix is still working on fixing a VX32L so I hope we can help !