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Martin
Martin, Technician
Category: TV
Satisfied Customers: 4834
Experience:  Studied video technologies before university. I still fix TV's in spare time.
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I have a samsung LNS3241DX/XAA the picture goes dark in 15-20

Customer Question

I have a samsung LNS3241DX/XAA the picture goes dark in 15-20 min. but if I turn off the TV and turn it back on the picture is fine for about 1 min. then goes dark again any thoughts
Submitted: 5 years ago.
Category: TV
Expert:  Martin replied 5 years ago.
Hello, welcome to Just Answer.

This look like a resistivity problem triggered by heat on the capacitors of the inverter board. It can always be something else, like a bad solder join so it's often best to change the whole part: http://www.shopjimmy.com/cmo-27-14240-019-backlight-inverter.htm

Bad capacitors usually show around 3 year of use. The problem usually get worst as current leaking in the capacitor damage them faster and you may get only 8-12 min before the picture goes dark in the coming week/month .

The dark caused by an inverter is not the same as if the main video would fail (another possible cause). When it's the inverter the back light just turn off. That mean that if you try it in a dark room, the screen should not leak any light (being pitch black instead of the usual dark gray).
Customer: replied 5 years ago.
so you think its the backlight inverter board not the main board? thanks
Expert:  Martin replied 5 years ago.
Yes. Those are very fragile by the high tension nature and production of lot of harmonics. The LCD with LED backlight (in opposition to those with inverter/ccfl) are "in theory" less prone to those failure (we will have to wait 2 or 3 year to really know it it's the case).
Martin and 3 other TV Specialists are ready to help you
Customer: replied 5 years ago.
Hi, I order a new inverter board and got it today installed it and the same thing happens the screen goes dark after a couple of minutes so should I replace the main board now? Thanks Gary
Expert:  Martin replied 5 years ago.
Ok, do you have any kind of blinking indicator at any point?

You still have sound all the time until you turn OFF the TV? And you can turn it OFF normally (no need to pull the plug)?

When it goes dark, if you close all light in the room so it's completely dark, does the screen become perfectly dark just as when it's not powered at all?
Customer: replied 5 years ago.

The tv goes on and off normaly and sound is fine the picture goes dark not off or black and no blinking.

Thanks Gary

Expert:  Martin replied 5 years ago.
If the TV goes off normally, it seem to get enough power. If it's dark and not black, then it's not related to the inverter (but be prepared to have that one fail eventually). As it definitively look like a capacitor/heat problem (that may still look fine at a visual inspection) the best is probably to have all of them inspected at a repair shop. Those usually fail 2 or 3 years after buying a TV (and TV companies know this).

If the TV still do this with all it's gut open on a test bench, i sometime can find the offender by using a directed jet or air (or many) to keep capacitors cool one by one (or in combination) and then change the bad(s) one. Sometime just opening up give enough air and i need to test them all for resistivity.