Vizio SV472XVT won't turn on

[cmitchel]

Hello all. I am trying to get my TV working again and could use some help to determine where my problem lies.

Backstory
My TV doubles as a normal TV and a computer monitor for movies. A while back all my HDMI ports went out and I had to switch to component connections. From what I read, the HDMI ports are very sensitive to surges and can get fried even if using a surge protector power strip and the only fix was a new main board. Everything else about the TV worked fine, so I lived with using component video. Months later as I was watching TV my screen went black all of a sudden and the power light switched from white (on) to orange (standby). I don't recall hearing any audible pop of a fuse being blown. I tried both remote and TV power buttons and even unplugged it from the wall to power cycle it, but couldn't get more than just the orange light to come back on.

TV Specs
Brand: Vizio
Model No: SV472XVT Rev. B1.20.4
Serial No: LSPFKBL0500120
Display No: LC470WUL (SB)(M3)
Main board No: 0171-2272-2937 / 3647-0172-0150(7F)
Power Supply Unit No: 0500-0507-0710
Inverter board No: 6917L-0013C


Troubleshooting
I have already opened it up once and checked a few things with my multimeter. The 3 fuses on the main board checked out OK. The main fuse on the power supply unit at first read good, but later on I found it to be blown, so I put in a temporary replacement for now. I've been reading that I need to check all the voltage regulators to make sure they all check out as good. This will be my next step. If I can determine all I need is a new circuit component then I'll be very happy, but I am prepared to order a new main board and possibly power supply board if need be.

Help
If anyone out there knows if there is a common solution to my problem that would greatly help. If more information or photos are needed, just let me know what all I need to check (continuity, voltage, resistance, amperage, etc.) and I will report back.

Thanks for the help in advance!

[dick_barton]

Re: Vizio SV472XVT won't turn on

What supplies have you measured and can you list them. Example
CON1, Pin1, 12V,0.0V
CON1 Pin2, P_On, 3V

That is:-
CON1 Pin 1 labelled 12V reads 0V
CON1 Pin2 labelled P_On reads 3V
Etc


That could help to determine the fault.

[cmitchel]

Re: Vizio SV472XVT won't turn on

All I could get a reading on was the incoming power CN1,Pin1,L,120V / CN1,Pin3,N,0V. I also had 120V at both sides of the fuse. On connectors CN2 through CN6 going out to the other boards I got a reading of 0V on all pins, but previously I know I was reading some voltage. A few of the voltage regulators on the primary side (Q601, Q602, Q801, Q905) had around 58.8-60V at them along with the primary side of the D903 transformer. I may have fried something when I was reading the voltage off Q905 and my meter lead slipped and shorted across two of the pins.

This was all measured from ground with all the wiring to the other boards removed. I'll check again tonight with all the other boards plugged back in to see if I get anything different.

[budm]

Re: Vizio SV472XVT won't turn on

When you check the DCV in the primary side, you do not use chassis as the GND ref, you have to use the negative leg of the main filter cap in the primary side as the GND ref for your meter, the secondary cold side you can use the chassis as the GND ref.
So lets fined out if you have at least 5VSTBY on the cold side first.

[cmitchel]

Re: Vizio SV472XVT won't turn on

Unfortunately my main filter cap is under a large metal shield with no access to the top side. I'll have to unmount the whole board from the tv, flip it over, and make some leads to tie all the grounds back to the tv chassis as I can't tell if they are all connected electrically on the board.

[budm]

Re: Vizio SV472XVT won't turn on

So right now all 5 connectors on the cold side have no DCV at all?
You can run the power supply board by itself out off the chassis so you can test the DCV between the two legs of the main filter cap C804, it should have about 160VDC.

Vizio 0500-0507-0710 (DPS-286BPA) Power Supply Unit

Pictures provided by shopjimmy.

[cmitchel]

Re: Vizio SV472XVT won't turn on

Budm,
Correct 0.0 DCV on all the connectors on the cold side currently (unless i need to replace a fuse on my multimeter). I'll pull the board out and check the voltage on C804 when I get home and report back.

[budm]

Re: Vizio SV472XVT won't turn on

Budm,
Correct 0.0 DCV on all the connectors on the cold side currently (unless i need to replace a fuse on my multimeter). I'll pull the board out and check the voltage on C804 when I get home and report back.

That means the standby power supply is dead. We need to find out if we do have about 160VDC between the two legs of the main filter cap first.
BTW, you should plug the board into the GFCI outlet to protect yourself.

[dick_barton]

Re: Vizio SV472XVT won't turn on

There's a repair kit listed which may help.

http://www.ebay.com/itm/Sharp-RDENCA...-/251847463491

[budm]

Re: Vizio SV472XVT won't turn on

If the picture of the parts as shown on the EBAY is correct, then it is not the right parts for his board because his board uses SMD SMPS IC for driving the Power MOSFET, the one on EBAY is the Power SMPS IC.
The board on EBAY is DPS-286AP, his board is DPS-286BP.

[cmitchel]

Re: Vizio SV472XVT won't turn on

I did find a full working board for only $40 including shipping that I could get if need be.

http://www.ebay.com/itm/272162075486...%3AMEBIDX%3AIT

[dick_barton]

Re: Vizio SV472XVT won't turn on

Thanks Budm for spotting my error. I don't like to offer incorrect information and I missed that on.

[cmitchel]

Re: Vizio SV472XVT won't turn on

So right now all 5 connectors on the cold side have no DCV at all?
You can run the power supply board by itself out off the chassis so you can test the DCV between the two legs of the main filter cap C804, it should have about 160VDC.

Vizio 0500-0507-0710 (DPS-286BPA) Power Supply Unit

Pictures provided by shopjimmy.

So I pulled the power supply board out, made sure I was using an outlet protected on a GFI breaker, plugged it up, and immediately tripped my breaker. I then made sure I had a good ground connection to the board, reset my breaker, and tried again only to get a spark out the board and a blown fuse. Replaced the fuse, put the board back on the TV chassis, plugged it in, and blew the second fuse. Tried one more time with a slightly higher ampacity fuse, only to get the same result.

So new board from ebay is on order and should be in next week.

[budm]

Re: Vizio SV472XVT won't turn on

Something that was ready to fail had failed badly?

[cmitchel]

Re: Vizio SV472XVT won't turn on

Ok, I got the new power supply board installed and no blown fuses so far, but TV still doesn't turn on. I've got power coming in and my Vizio logo is lit up orange. Measured voltages at connectors are as below:

All pins on CN2 going to inverter board read 0.0V (24V, SGDN2, A, B, C).

CN4, Pin 1, 18V, 0.0V
CN4, Pin 2, 18V, 0.0V
CN4, Pin 3, SGDN3, 0.0V
CN4, Pin 3, SGDN3, 0.0V

CN5, Pin 1, PSON, 0.0V
CN5, Pin 2, 12V, 0.0V
CN5, Pin 3, 12V, 0.0V
CN5, Pin 4, SGDN3, 0.0V
CN5, Pin 5, SGDN3, 0.0V
CN5, Pin 6, SGDN3, 0.0V
CN5, Pin 7, SGDN3, 0.0V
CN5, Pin 8, SGDN3, 0.0V
CN5, Pin 9, SGDN3, 0.0V
CN5, Pin 10, SGDN3, 0.0V
CN5, Pin 11, +5VSB, 5.21V
CN5, Pin 12, +5VSB, 5.21V
CN5, Pin 13, +5VSB, 5.21V
CN5, Pin 14, +5VSB, 5.21V
CN5, Pin 15, +5VSB, 5.21V

CN6, Pin 1, A, 0.0V
CN6, Pin 2, B, 0.0V

[cmitchel]

Re: Vizio SV472XVT won't turn on

I also checked the voltage across the main filter cap C804 and I have 161.3V.

[dick_barton]

Re: Vizio SV472XVT won't turn on

Disconnect the power supply from the main board and connect 5vsb to PSon using a 1K resistor and measure the voltages again. Leave main board disconnected during the test.

[budm]

Re: Vizio SV472XVT won't turn on

It looks to me the main board is also bad, there is not any command signals from the main board at all.

[dick_barton]

Re: Vizio SV472XVT won't turn on

Definately looks like no PS_On from the main board but could it be an inverter error?

[budm]

Re: Vizio SV472XVT won't turn on

I do not see the Ivr-error pin, and these old VIZIO do not use the error signal from inverter.
The 'A' is for the BL-ON, the 'B' is for Dimming control, right now all 3 signals are not present.
I think the clue about the main board is in post #1 "A while back all my HDMI ports went out and I had to switch to component connections"
BTW, db, you are able to go to shopjimmy website OK? I see some people here saying that they cannot access the site from Euro.