Samsung ln-t4065f - vertical lines

[ahickman]

Just had a Samsung LN-t4065F 42" dropped off by a friend that powers up but displays only vertical color lines. Have not opened it yet, but looking for suggestions on where to start looking. Loose T-con controller cable?

aaron

[tom66]

Re: Samsung ln-t4065f - vertical lines

Definitely looks like T-con. I had a similar problem with a Samsung which turned out to be a failed voltage regulator on the T-con.

[ahickman]

Re: Samsung ln-t4065f - vertical lines

Thanks. Just got back to my desk and decided to try something I recalled from another thread. Held in the Menu button and powered on. Fired right up and clear picture from VGA source. I did notice a few pixels were striped, but went away as the image refreshed. Nice to know that it is not totally disfunctional. Taking the back cover off now.

[tom66]

Re: Samsung ln-t4065f - vertical lines

Thanks. Just got back to my desk and decided to try something I recalled from another thread. Held in the Menu button and powered on. Fired right up and clear picture from VGA source. I did notice a few pixels were striped, but went away as the image refreshed. Nice to know that it is not totally disfunctional. Taking the back cover off now.

That may be a coincidence. When I saw the mentioned Samsung TV, it was faulty. When I got it home it actually worked - the regulator was intermittently failing. If the output voltage of that regulator is low, the T-con may be becoming confused, and the Menu button may be resetting it...

[ahickman]

Re: Samsung ln-t4065f - vertical lines

Curious as to how you identified the failing regulator. I assume it was a three pin type regulator (Vin, Vout, GND)? Did you see ripple on the Vout or just watch the pin with a scope, looking for voltage level changes? Recall, which regulator it was?

[ahickman]

Re: Samsung ln-t4065f - vertical lines

Opened it up this AM and right away noticed the bad caps on the PS. It is a Hansol BN44-00167A board and I found right many threads on various forums. Looking at the 1000uF @ 10V caps, I found ESR's in the 2.2 range. CM807, CM807 and CM809 had decent ESR readings of 0.1x - 0.2x and the main filtering cap was also 0.2x ohms.

All I have in my parts drawer are some 1000uF @ 35V / 105 deg. capacitors. Can anyone tell me if the higher voltage rated caps can be used in place?

[truep]

Re: Samsung ln-t4065f - vertical lines

The 35V caps will work if they are low ESR caps and IF they will fit.

[ahickman]

Re: Samsung ln-t4065f - vertical lines

Thanks. Just replaced four of the 1000uf 10V with 1000uF @ 35V and turned it on. Big Bang Theory is playing now! Thanks for the help guys.

[tom66]

Re: Samsung ln-t4065f - vertical lines

Curious. I have heard of bad caps causing picture freezing and possibly lines on Samsungs... but never seen it before in person or on the forums.

On my board it was a standard 1117 regulator with a 2.5V output voltage, measuring close to 1.3V. The output voltage presumably would occasionally stabilise (as it worked once), but most of the time would be stuck at 1.3V.