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Planning to install filter on IR receiver in Samsung PN42C450... tips?

post #1 of 7
Thread Starter 
So I've had a long-standing issue with this Samsung in that it occasionally turns itself off - or rather, it gets turned off because of stray light in the room or from the screen itself.

It seems that the IR receiver (for the remote control) is simply too sensitive. Perhaps it is defective or out of alignment, but in any case it's just not right. Samsung has not been helpful in resolving this (make sure you aren't pressing any buttons on the remote, make sure your cable box isn't set to turn the display off, etc). The problem occurs on any input and even when all remotes are physically removed from the room. Replaying specific moments on ESPN or CNBC (usually bright transitions or the stock ticker) via DVR can faithfully reproduce the issue about 3 out of 10 times.

Another hint that it's receiving stray commands is that you can see the red LED blink just before switching off - the same thing it does when receiving legit commands from the remote.

Anyway, this happens infrequently enough that I never sent it back but now I'm well past my warranty and for whatever reason it's turned off three times this morning so far (it's a sunny day). My plan is to open up the case, access the IR receiver and put a gel filter (like neutral gray) over it in an attempt to reduce its sensitivity.

What would be great is if there was a service menu option for tweaking this sensitivity, but so far I've not found one!

Let me know if anyone has any experience with this bizzarre sort of problem and can offer any tips... thx!
post #2 of 7
Thread Starter 
OK, so I removed the back panel (~16 screws!) and located the cable which connects the front panel buttons + IR sensor board to the main board. Conveniently, the pins are labeled on the board & the IR sensor gets its own.

Removing the whole cable prevents any of the buttons or the remote from working (obviously). Removing just the Black cable corresponding to PIN 1 (IR) allows the buttons to work but the remote is disabled. See pic.



I've also removed the gaffer's tape that I added to the inner bezel (which reduced the occurances of light from the screen turning the set off), and I'll set the screen to full brightness. The set is back in it's normal location and will leave it on for a few days to see if it turns itself off.

If it does not... should I attempt to add a filter as originally planned or do you think there's a good place to source a replacement board/IR sensor?
post #3 of 7
Thread Starter 
Well the set was on for a good portion of the weekend and there were no errant power-offs. At this point I'm going to say that the issue is almost certainly related to the IR sensor.

Next step will be to get that button/sensor sub-board out and go about attaching some sort of filter to the front of it. Hopefully this will deaden the sensor enough that it'll still work with the remote but not pick up stray light. (Since it happens somewhat infrequently, my guess is that it's just on the borderline of being "too sensitive".)

Also, I've noticed that there haven't been any replies on this thread... Understandable since this is an obscure problem; hopefully my documentation of it & the fix will benefit someone down the road.
post #4 of 7
you could try putting the filter on in front of the sensor to see if it works. or do you think it is coming from inside the case?
post #5 of 7
Thread Starter 
Quote:
Originally Posted by renfield33 View Post

you could try putting the filter on in front of the sensor to see if it works. or do you think it is coming from inside the case?

That would have been ideal, but this model has a translucent case - light gets in from all over the place so it's difficult to block. In fact, I was able to reduce the occurrence of power-offs caused by light from the screen by putting some black tape on the inner bezel of the case at the bottom-right (the relief where the case makes a frame around the screen).
post #6 of 7
Hi:

I want to relate a story I had with a similar problem, but with different equipment. This may or may not apply in your case..

I have an equipment rack that I had placed between two windows in my apt. A brief time later, my AVR started changing volume on its own and even changing inputs by itself!

I thought it was the IR sensor, so I covered it in black tape.

That did nothing. I finally thought about the cell towers six stories below, and desperate for a fix, I moved the equipment rack about fifteen feet to a corner on the same wall.

Voila - No more erratic behavior from the AVR.

As I said,this may not help you in your situation, but I thought I'd just put it out there 'cause I definitely worked for me.
post #7 of 7
Thread Starter 
Thanks for the reply; it's something worth considering.

I hadn't posted an update since there seemed to be a lack of interest and, well, I'm no better off than where I had started! After adding a switch that physically disconnects the IR sensor I still have occasional problems with the TV shutting itself off.

At this point I've more or less given up. Probably should have done something about it sooner, but at this point it's just going to be a minor inconvenience I have to deal with. As it's not my main set it's not a huge problem.

I am rather curious as to what the problem is... Maybe the power supply is flacky? Perhaps there are deeper issues with the main board? Lacking a knowledge of how to (and equipment required to) diagnose these types of issues I think I'm at the end of the road.
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