Vizio SV320vxt popping fuses like it made it up.

[selldoor]

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

I think you should test the voltage across the BIG cap as there seemed to be some doubt earlier that it was operating correctly.
Meter on 600V DC and observe the polarity - HIGH voltage so great care.


Did you do this before you removed it?

[shwsrvcs]

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

oh.. fuses on the main board 2 by the power connection both read at .1 and beep on continuity setting

[shwsrvcs]

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

errr. didn't get that light fixture quite done, but I am gonna try again in the morning.. I did however find the voltages from the multimeter.. and they are with both the power button pressed and also in standby..

.3 for PSON
3.2 for 12v
5 v for svsb

and still no fuses blown since ever.. oh.. I pulled the main caps and checked em with the meter, they both dropped and then chlled at low reading. I decided to try and replace em just in case, but nope... no 68uf 470V at frys. will try marvac in the morning..

[shwsrvcs]

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

Hi- Now you have got it back on, I think you should test the voltage across the BIG cap as there seemed to be some doubt earlier that it was operating correctly.
Meter on 600V DC and observe the polarity - HIGH voltage so great care. Once the high voltage is established as ok move on to testing the outputs.

- you might want to read this
https://www.badcaps.net/forum/showth...t=19245&page=2

Post 40 has budm's load and voltage tester which you might want to try to see if your output voltages are sound.

I am crafting one today, need a couple of things from hardware store. going there now

dg

[shwsrvcs]

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

and sorry for the hold up on the reply.. I stayed up all night working on this and a toshiba laptop.... and a website.. and when I wrote about the power light coming back on, it was on my last patch of "awake" time left. I am just now getting back on the job and am heading out to pick up a 16" lcd panel for the laptop and a few fuses for this job. (currently running with one I borrowed from the E321VL I have up next to work on.

[shwsrvcs]

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

my bad, the screen isn't white.. it's just the amber light that turns white, the screen stays dark and moreover, its not getting a signal sent to it that I can see (as in not just the backlights aren't powering up, the main board isn't going up either) on those second set of mosfets on the primary side (q601 I believe) one was also not matching up. could it be that one should be replaced?

so far I've replaced, the rectifier and that first mosfet

that q601 on the board was reading as follows in comparison to the others which I take for "normal"

Q802 }{ 2.590 }{ 0.5 }{ 0.5 }
Q601 }{ 4.45 }{ 0.7 }{ 4.45 }
Q603 }{ 2.421 }{ 4.41 }{ 0.5 }

dg

[selldoor]

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

Hi- Now you have got it back on, I think you should test the voltage across the BIG cap as there seemed to be some doubt earlier that it was operating correctly.
Meter on 600V DC and observe the polarity - HIGH voltage so great care. Once the high voltage is established as ok move on to testing the outputs.

- you might want to read this
https://www.badcaps.net/forum/showth...t=19245&page=2

Post 40 has budm's load and voltage tester which you might want to try to see if your output voltages are sound.

[budm]

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

Do you mean the VZIO LOGO stays white instead of Amber? Or the TV screen just has white glow? Can you see the backlights are on?

[multimeter]

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

sorry did you mean the screen turns white,or the power light?

[multimeter]

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

also beacause you have a backlight,it means your inverters are working,unless the white screen dissapears after a few seconds

[multimeter]

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

Okay. on the fuses, I've been replacing them via the little cup connections exactly for the reason that I don't want to mess with the solder points.

I replaced that q801 mosfet and viola! the unit is no longer blowing fuses! the amber light is on, and then it turns white when the power is pressed!

it's just...

no screen turns on.. and there is not indication of sound.. although with no signal... there couldn't be any

checked the inverter board and it looks like this attached.

now the tv fires up,now check ALL outputs against there legends to make sure supply is healthy,if any arnt investigate why,a white screen could be a tcon smd fuse has blown,psu 1st

[shwsrvcs]

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

Okay. on the fuses, I've been replacing them via the little cup connections exactly for the reason that I don't want to mess with the solder points.

I replaced that q801 mosfet and viola! the unit is no longer blowing fuses! the amber light is on, and then it turns white when the power is pressed!

it's just...

no screen turns on.. and there is not indication of sound.. although with no signal... there couldn't be any

checked the inverter board and it looks like this attached.

[budm]

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

If you keep re-solder and solder in the fuses, sooner or later the traces will be damaged. Take the cap out and Ohm out the two pads where the cap was connected to to see if you read low Ohm also.

[multimeter]

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

oh wait did I say build back up on that ohm test? I took the board back off the panel and brought it back to the bench... I tested that again and noticed that, what I tought in haste was the charge building was really the charge leveling. it drops to zero at first but then after an initial change back up, settles into 0.2 reading that stays steady. which is what the multimeter does when the two terminals touch together.

I tested ohms on all the mosfets under the heatsink covers on the primary side

all are tested with the negative on the screw at the top and the pins below left to right

board#}{ Pin 1 }{ pin 2 }{ pin 3 }
Q801 }{ 1.3 }{ 0.2 }{ 0.2 }
Q802 }{ 2.590 }{ 0.5 }{ 0.5 }
Q601 }{ 4.45 }{ 0.7 }{ 4.45 }
Q603 }{ 2.421 }{ 4.41 }{ 0.5 }

these are all so non-uniform, I must be measuring something wrong. I'm going to research as soon as I wake up in the morning.

Dave G

the readings you are getting on the mosfets sound like they are still in circuit?,have you removed them then tested?,the .2 you seem to be getting from the primary cap sounds as if it is shorted,and definatley use the suggestion from budm bout the series lightbulb tester,if you have a esr meter check the primary cap ,if you dont then just straight replace that cap with the correct spec ,normaly if there is a dead short the fuse will be very black if its a glass fuse,if it is just age related failure then the glass will be clear and the fuse wire still visable inside the fuse,replace primary cap 1st.

[shwsrvcs]

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

oh wait did I say build back up on that ohm test? I took the board back off the panel and brought it back to the bench... I tested that again and noticed that, what I tought in haste was the charge building was really the charge leveling. it drops to zero at first but then after an initial change back up, settles into 0.2 reading that stays steady. which is what the multimeter does when the two terminals touch together.

I tested ohms on all the mosfets under the heatsink covers on the primary side

all are tested with the negative on the screw at the top and the pins below left to right

board#}{ Pin 1 }{ pin 2 }{ pin 3 }
Q801 }{ 1.3 }{ 0.2 }{ 0.2 }
Q802 }{ 2.590 }{ 0.5 }{ 0.5 }
Q601 }{ 4.45 }{ 0.7 }{ 4.45 }
Q603 }{ 2.421 }{ 4.41 }{ 0.5 }

these are all so non-uniform, I must be measuring something wrong. I'm going to research as soon as I wake up in the morning.

Dave G

[shwsrvcs]

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

I would Ohm out the + and - of the bridge after you install it, you should see the meter shows real low Ohm but then the resistance should rise up (as the cap is being charged up by the meter) into K Ohms range.

O came back here to my desk to grab a power cord to test my work, and so I tested this, and it did drop and build back up. All right! I thought.. here we go.

ffffip

not as loud as the pops before, but just a mild sound and a bit of glow at the incoming end of the fuse as it became open... i'm going to check that bridge rectifier again to make sure this new one is still working as it's intended and then I should check the mosfets? no, that main cap... I'm going to test that main cap... i'll do that when I return from getting something to drink at cvs..

drat.
DG

[budm]

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

I would Ohm out the + and - of the bridge after you install it, you should see the meter shows real low Ohm but then the resistance should rise up (as the cap is being charged up by the meter) into K Ohms range.

[shwsrvcs]

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

ah ha. thats a really good item right there. I'm going to make that for sure.

I got side tracked till now for a laptop monitor repair, but I'm heating up the Weller right now and am going to install that rectifier next. I'll report back again with the outcome.

Thanks again for all the assistance!

DG

[budm]

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

You may want to build one of this short indicator so you will not keep blowing your new fuses and new components, it is basically put the lamp in series with the load, for your TV, you can use 100 ~150Watts LAMP should be enough to see if the light comes on real bright and stay bright, come on bright for a second then dim down if it is OK. Since the bridge and the main DC filter cap are always on the minute you plug the TV into the outlet (you not have to turn the TV on), it lamps stays brigtly lit then you have problem.

[tom66]

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

The bridge rectifier is a common failure point in TVs, it seems. Replace it with a device similar to GBU4J, a 600V 6A part.

(If you're sure you're only going to use it in the US, you can get away with a 200V part, but going for a higher voltage rating will improve the safety margin and make it less likely you'll need to replace it again.)