Samsung 55NU6900 - Heard a pop then tv is dead, burnt cap & dead fuse

[Pwtzz]

Hi All,

Before replacing what I know to be bad even with my novice experience. What I have checked at the moment is the fuse and the obvious burnt capacitor. I haven't bought any replacement parts yet.
I still have no idea how this happened but could just be plain old turned bad. What other stuff should I consider buying as replacement? thanks in advance.

Edit: I saw that a replacement board can be had for about $50. I would rather attempt to fix before just replacement the board.

[R_J]

Re: Samsung 55NU6900 - Heard a pop then tv is dead, burnt cap & dead fuse

This looks like it is the PFC circuit. It might be that the cap shorted on its own, maybe the voltage rating was just border line, (1kv instead of 2kv), Remove the shorted cap, then check the two resistors next to the cap, they are in parallel and should read very low. Also check the mosfet under the heatsink to see if it is shorted or not, Then check the diodes in that circuit, if there are no obvious shorts, it might just be the cap.

If there is other faults with this board, shopjimmy recommends changing the backlights as well as the board.

[CapLeaker]

Re: Samsung 55NU6900 - Heard a pop then tv is dead, burnt cap & dead fuse

take that 450V cap out. Then measure on those pads for short or not. You definitely need a new cap and a fuse.

[Pwtzz]

Re: Samsung 55NU6900 - Heard a pop then tv is dead, burnt cap & dead fuse

This looks like it is the PFC circuit. It might be that the cap shorted on its own, maybe the voltage rating was just border line, (1kv instead of 2kv), Remove the shorted cap, then check the two resistors next to the cap, they are in parallel and should read very low. Also check the mosfet under the heatsink to see if it is shorted or not, Then check the diodes in that circuit, if there are no obvious shorts, it might just be the cap.

If there is other faults with this board, shopjimmy recommends changing the backlights as well as the board.

take that 450V cap out. Then measure on those pads for short or not. You definitely need a new cap and a fuse.

I took off the burnt cap, the pads are shorted and more caps are shorted --the blue caps and the square cap (maybe more).
The mosfet is shorted also and plenty of diodes are bad (going both ways, could this be due to faulty mosfet?)

Thanks for the tip. I'm going to remove the bad mosfet to see if it affects the shorted caps and bad diodes. I'll open up the screen too and check for visible damages on the backlight.

[CapLeaker]

Re: Samsung 55NU6900 - Heard a pop then tv is dead, burnt cap & dead fuse

Remove the blue cap, that is blown. Check the 2 resistors for spec value (resistors go higher in value or open), remove the mosfet and check it and keep on going until you removed all the shorted or open part(s). Sometimes it can be easy as a new cap and a fuse. Other times you hang in there changing diodes, resistors, mosfets and capacitors.