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Crumbtrail TV Forums: TV Equipment: Plasma TV Forum:
Samsung 51 inch works intermittently



New User

Jan 14, 2017, 6:01 PM

Post #1 of 3 (6582 views)
Samsung 51 inch works intermittently Can't Post

Newbie here. First post. I searched first, but may have missed existing posts on my issue.

I have a Samsung PN51F4500AF TV that was installed outside in a screened-in lanai in Central Florida. It is mounted such that it will never get rained on or be in sunlight. Of course it is exposed to heat, humidity, etc. It was mounted in mid-2013 and we rarely use it. A month or so ago I turned it on and it worked intermittently in that the picture would come and go. This was not abnormal as it is connected to my receiver in the house which also feeds our main indoor Sharp TV. My receiver has a HDMI jack to allow shadowing of the main Sharp TV onto the outside Samsung TV. Anytime the outside Samsung TV is turned on it always causes the main Sharp TV in the house to lose video for a few seconds before recovering. I have always attributed that to HDMI syncing, but could be wrong. This time it did all of that, but after a few minutes everything settled out the outdoor Samsung TV picture went away. I tried turning it off and on a few times, but it was unresponsive. The red standby light was not on. The only way I could get the standby light to come on was to unplug the TV and plug it back in. I would then turn the TV on and the standby light would go out (as it should), but still no picture. I repeated this process numerous times with the same result. No picture or audio.
I took the TV down and brought it into the house and the next day decided to check for bulging capacitors. Everything appeared to be normal except for some minor corrosion on some of the component leads (as expected). I decided to check the voltages. They are as follows:

Vs: 185.3 V DC (should be 205 V DC)
Va: 53 V DC (should be 58 V DC)
Vsc: -172.9 V DC (should be -175 V DC)

So it looks like the Vs and Va are a bit low. Just for fun I decided to recheck the voltages with an input signal from my cable box. I did that and do my surprise the TV worked perfectly. Great picture and sound. The voltages were unchanged. I let it run for several hours to see if it would fail, but it never did.

This TV mounts just under a 10 ft ceiling outside in the lanai and before I seal everything back up and go through the hassle of re-mounting it I wanted to check with members here. The last thing I want to do is to go through all that trouble only to have the problem re-occur. Would anyone advise on adjusting these voltages to their proper levels?
Would spraying a conformal coating (like Humiseal) on the boards be beneficial to reduce further corrosion?

When I first put the TV out there I knew its life span would be shorter than an indoor set, so I accept that fact, but wanted to see if I could get a little more life out of it first.
Thanks in advance.

New User

Feb 4, 2017, 7:02 PM

Post #2 of 3 (6542 views)
Re: [Titan4] Samsung 51 inch works intermittently [In reply to] Can't Post

After letting the TV sit for several weeks I decided that I was going to adjust the Vs and Va voltages. When I turned the TV on the failure mode repeated and there was no picture. The red standby light went out as normal, but no picture. While it was in the failure mode I decided to recheck Va, Vs, and Vsc. All were pretty much right on the money. I noticed also that the green logic light is not blinking while it is in this failure mode (no picture). So in a nutshell I have two modes:

1) When the TV works the voltages are a bit low as listed in the original post.
2) When the TV does not work the voltages are correct, but no picture and no green blinking logic light.


In Reply To

New User

Feb 12, 2017, 3:53 PM

Post #3 of 3 (6504 views)
Re: [Titan4] Samsung 51 inch works intermittently [In reply to] Can't Post

It ended up being the power supply board. Replaced it with one from ebay and now it works great.


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