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Using a USB-connected LED strip light for back-lighting a Sony KDL-46HX729

Last response: in Home Theatre
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August 30, 2013 9:52:39 AM

I recently purchased a new, open-box Sony Bravia KDL-46HX729 LED HDTV with full 18-month manufacturer warranty from an authorized Sony retailer. I have wall-mounted the set, and for back-lighting I am using a Soundscience (by Antec) HDTV Bias Lighting LED light strip which has a USB connector and an in-line on/off switch. The lighting effect is perfect and it functions as designed, coming on when the TV is powered on and turning off within about 30 seconds of the TV being powered off.

The strange issue I am having is that the LED light strip will also turn on (and then eventually turn back off) at odd times when the TV is off. The timing seems to be random, and since this is in the master bedroom the occasional 2:00 AM or 4:00 AM burst of white light can be extremely annoying. As far as I know, the USB port should not be receiving voltage when the TV is in stand-by or off mode, and I am puzzled what could be causing this issue.

Obviously, I could resort to using the in-line on/off switch on the light strip, but that is a cumbersome and very inconvenient solution which would considerably diminish the utility of the back-lighting. It is also not the way that this light was intended to be used.

I have contacted Sony customer support with (predictably) no meaningful help. One CSR said this was "normal" (even while confirming the the USB port should not be powered when the TV is in standby!) and a second suggested that I might need to ask for warranty repair service without offering any diagnosis of the issue.

I have performed the following troubleshooting steps with no improvement:

1) Tested both USB ports
2) Tried all three USB display settings on the TV ("slideshow," "thumbnail" and "off")
3) Tested with the TV powered off (vs. standby mode)
4) Disabled the wireless connection
5) Disabled the CEC (which Sony calls "Bravia Sync") with the Home Theater System
6) Performed a factory reset of the TV
7) Tested with a second LED light strip
8) I have also tested the LED light strip on my living room Sony XBR-55HX929, where I did not observe the random on/off anomaly.

The TV's only inputs at present are coaxial cable directly from the wall outlet (Comcast digital cable TV) and HDMI to a Sony HT-CT350 Home Theatre System. All other components (TiVo and BRD/VHS player) are connected via HDMI to the HT-CT350. The TV is plugged into a Rapid Link Power Kit wall outlet which, in turn, is plugged into a Cyberpower UPS serving all four components.

It's bugging me that I can't isolate the cause of this issue and I'm hoping someone here can shed some light. Perhaps there's a simple solution (or even just an explanation) that escapes me. If nothing else, it would be helpful if I could approach Sony's warranty service with the information that "X" is causing a malfunction.

Best solution

August 30, 2013 11:48:25 AM

Hi
Since thats an internet connected TV I wonder if it powering up at certain intervals in order to download updates.
Under normal conditions you would never notice as it would not need to power the panel only the processor for the web browser.
You notice it because it is powering up the 5V line and turning on your LEDs'.
I have no idea how you would control the update intervals.
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August 30, 2013 12:36:22 PM

makkem said:
Hi
Since thats an internet connected TV I wonder if it powering up at certain intervals in order to download updates.
Under normal conditions you would never notice as it would not need to power the panel only the processor for the web browser.
You notice it because it is powering up the 5V line and turning on your LEDs'.
I have no idea how you would control the update intervals.


Thanks for your response.

However, as I noted in troubleshooting step #4, I tried disabling the wireless internet connection and still observed the light turning on/off with the TV in standby mode.

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August 30, 2013 1:26:34 PM

Thats true but the TV likely would power up at certain times to check for updates and would not know there was no internet connection until after it started up.
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August 30, 2013 2:43:56 PM

makkem said:
Thats true but the TV likely would power up at certain times to check for updates and would not know there was no internet connection until after it started up.


I guess there's no way I'll be able to investigate the likelihood of what you're postulating, but I doubt that it's the cause. Firstly, there are very few firmware updates to these models; secondly, I've already downloaded the latest update and have verified that the FW is up to date; thirdly, I suspect (but do not know) that the TV will not seek an update if it is not connected to the internet either via ethernet or wireless network; and fourthly, I have not observed the anomaly on my other wirelessly networked set, the previously cited XBR-55HX929.

Still, I can't dismiss the possibility that you could be on to something.

m
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!