Vizio SV320vxt popping fuses like it made it up.

[budm]

Re: Vizio SV320vxt popping fuses like it made it up.

The two main DC caps (two long brown cap 450VDC rating) are in parallel to get enough filter (they are selected for the amount of the AC ripple (riding on top of the DC) that the circuits are allowed to accept).
This power supply board has PFC Voltage booster circuits, when the TV is OFF, the DC on that cap should be around 165~170Vdc, when the board gets the PS_ON signal from main board, the voltage on the caps should go up to around 390~400Vdc.
Most TV in the last 2~3 years use PFC circuit to get power factor as close to 1 as possible.

[shwsrvcs]

Re: Vizio SV320vxt popping fuses like it made it up.

okay.. now that I've got them both connected properly they both read 167.6 with the power on standby and 163,4 when the vizio light is illuiminated.

[shwsrvcs]

Re: Vizio SV320vxt popping fuses like it made it up.

The two main DC caps (two long brown cap 450VDC rating) are in parallel to get enough filter (they are selected for the amount of the AC ripple (riding on top of the DC) that the circuits are allowed to accept).
This power supply board has PFC Voltage booster circuits, when the TV is OFF, the DC on that cap should be around 165~170Vdc, when the board gets the PS_ON signal from main board, the voltage on the caps should go up to around 390~400Vdc.
Most TV in the last 2~3 years use PFC circuit to get power factor as close to 1 as possible.

Ohhh ok. I see that! so let me bring that board back here to my desk...

dang it...

I am so dumb. I touched the probes together cuz I decided to see if the voltage had changed for either of the two, with the additional info on the pdf, it was clear as water how those two interacted with the next part on the board.. and those mosfets above them.. but anyways... they touched and there was that distinct pop of electricity. now the caps don't read any voltage at all, the main fuse, beep on the continuity setting, but now the meter reading fluctuates while it beeps... damn it.

[tom66]

Re: Vizio SV320vxt popping fuses like it made it up.

Check the PFC diode on the primary side.

[budm]

Re: Vizio SV320vxt popping fuses like it made it up.

By the way, my post #41 with the attached PDF, I also circle some caps that look like they have domed tops, did you verify that, may be its the distorted pix.

[shwsrvcs]

Re: Vizio SV320vxt popping fuses like it made it up.

I took these pics earlier then walked away from it for a day to try another avenue hopefully be successful this time.

Here are 4 views of those caps, they do look odd at certain angles, but when I look closer then they look okay...

[selldoor]

Re: Vizio SV320vxt popping fuses like it made it up.

Hi I have just been reading through the thread and have had what I hope is a eureka moment.
In post 19 there is a picture of the inverter board and there is a white sm fuse. I cant see that this is referred to in the text and wonder if you have tested it at any time?

[shwsrvcs]

Re: Vizio SV320vxt popping fuses like it made it up.

Hi I have just been reading through the thread and have had what I hope is a eureka moment.
In post 19 there is a picture of the inverter board and there is a white sm fuse. I cant see that this is referred to in the text and wonder if you have tested it at any time?

You know, I took a break yesterday to write out my letter of resignation from the porn biz to jump into the deep end here in this line of work. (seriously, i've been webmastering in porn since 99 but its a dead industry now) but now I'm getting ready to test another board for another vizio here. I'm going to pull that back on the bench as soon as I get this testing finished.

Thanks for the idea!

DG

[selldoor]

Re: Vizio SV320vxt popping fuses like it made it up.

There are also two ceramic fuses on the main board F1 & F2 - have you tested those?

[shwsrvcs]

Re: Vizio SV320vxt popping fuses like it made it up.

I took the time time walk away for a bit and come back fresh. I really appreciate all the help I've received here and this forum is the absolute best I've seen in a long while.. at least 10 years of bbs/forum usage.

I tried the last couple suggestions and all the ceramic fuses come back as good. I went thru again today and tested the voltages coming from the main board back (PSON) and it shows an increase when the power is turned on, the amber light in the front turns white when the power is turned on, the power will stay on (amber light is white) until it is turned off.

Checked to find if the video is being sent to the screen but I am unable to see any thing while using my led flash on my phone or incandescent flashlight.

so I've got power all the way up to when it comes back to the switch mode power, but at that point from what I can tell, there is no signal to the screen and no power to the backlight. I really wish I could have figured this out but I think I'm out of time, well... yes, I'm out of time,

The person I'm working on this for has been and is still being very patient but realistically, Im thinking maybe.. I've taken time in this repair that would better used by maybe ordering the 60 dollar board on eBay and just replacing it?

Really I wish there was more of standards type thing going on at the component level, if not for all brands, at least across each brand. I had 4 vizio's thru here last week and each one of them has it's own way of connecting between boards, the ccfl's. I understand the tech is ever expanding but maybe with the advent of led back lights the need for just downright funky boards in each model in a product line can give way to something more modular and interchangeable.