Vizio VP50 blowing fuses.

[Heliotropic]

I am having a problem with 1 specific fuse on the power supply board (Samsung PSPF561A01A) that keeps blowing (250v 8A, I believe it is F180 location).
The fuse are not blowing instantly, it takes a few days/weeks sometimes a month before it blows again. I have been replacing them with slo-blow fuses. I've installed a capacitor "kit" that replaced 6 of the capacitors, but the fuse has blown again since then. I purchased an ESR meter and re-tested those capacitors and they seem to be fine (the old ones were good too). I do not see any signs of other capacitors bulging or leaking. I did take a few others off the board and test them, there was one that I'm a little suspicious of. But before I just start throwing more parts at it I have a few questions...

Are there any components that are known to go bad on this specific model TV/board that causes this problem?
Is there a specific component I should be testing.

Thanks for any help.

[tom66]

Re: Vizio VP50 blowing fuses.

If that were happening I would increase the fuse rating to approx 10 to 12 amps.

[Heliotropic]

Re: Vizio VP50 blowing fuses.

There also seems to be quite a bit of heat being produced at the fuse. A few times that I've went to change the fuse I find a ball of solder that seems to have seeped from under the cap onto the glass.
Is it safe to increase the size of the fuse? I always thought the fuse is set at that specific amp to protect the rest of the board.

[tom66]

Re: Vizio VP50 blowing fuses.

Generally, the fuse rating needs to be low enough such that the board can fail in such a way that it can blow before any other part causes substantial damage. The cabling and plug also should be rated to handle the fault current, so increasing the rating to 10 or 12 amps should be acceptable.

[R_J]

Re: Vizio VP50 blowing fuses.

Is the fuse in a fuse holder? I have seen faulty fuse holders cause this problem, replace the fuse holder. If the connection between the fuse and the holder is a bit resistive it will cause heat, once it is heated the spring tension will be lost. I uploaded a picture of a bad holder, note the darker contacts on the left vs the nice shinny contact on the right.

[Heliotropic]

Re: Vizio VP50 blowing fuses.

Is the fuse in a fuse holder? I have seen faulty fuse holders cause this problem, replace the fuse holder. If the connection between the fuse and the holder is a bit resistive it will cause heat, once it is heated the spring tension will be lost. I uploaded a picture of a bad holder, note the darker contacts on the left vs the nice shinny contact on the right.

There is definitely discoloration on one end of my fuse holder. There seems to still be plenty of tension for holding the fuse though. I'll go ahead and replace it anyway. Are they general in connection and mounting, or am I going to have to research a part number? Link?

Any other suggestions?

Thanks for the advice.

[Tvbob]

Re: Vizio VP50 blowing fuses.

Was the original a ceramic fuse? If you are replacing with glass are they black? (meaning a catastrophic fuse failure) Is the ac wall plug tight in the socket? change the fuse holder like R_J suggested. The lower the ac line voltage is, The more current the set will draw.

[Heliotropic]

Re: Vizio VP50 blowing fuses.

Was the original a ceramic fuse? If you are replacing with glass are they black? (meaning a catastrophic fuse failure) Is the ac wall plug tight in the socket? change the fuse holder like R_J suggested. The lower the ac line voltage is, The more current the set will draw.

Yes, the original fuse was ceramic. I did have to purchase some glass slo-blow because that is all they had locally. The glass ones weren't completely blackened, just the filament was broken. The last glass one I put in had the solder seeping out of the cap but was still working in the TV.
I have burned through all the glass ones I had and now back to ceramics.

[Heliotropic]

Re: Vizio VP50 blowing fuses.

I snapped a few pic's if it helps at all. The new (2 day old) ceramic fuse is also getting melted. The capacitors marked with red (6 ea.) are the ones that I replaced with the "kit".
I am having atrouble locating the correct fuse holder to order from Digikey. Of the ones they have listed with a picture, none match exactly what I have. I couldn't find a part number on the fuse holder itself (unless it's on the underside) other than a LF marking. I assume that stands for Littelfuse. Any suggestions?

[Tvbob]

Re: Vizio VP50 blowing fuses.

Both sides of the ac line are fused. The fuse Is not (blowing) it is failing due to heat. Do a search on xbay for (5mm x 20mm circuit board fuse holder)you will find one or more there.

[R_J]

Re: Vizio VP50 blowing fuses.

Those fuse holders are used on many boards, I got mine off an old lg ysus, check with a electronic shop, they might let you take one off an old board

[ZURIT]

Re: Vizio VP50 blowing fuses.

Please replace fuse holder or repair.When all components check OK TV working and after couple hours or days blowing T8A250V main(input) fuse I found bad fuse connection overheated fuse holder contacts.