Home av remote control problem mistery. How can I fix this? - Page 1
Forum section: electronics / projects

author: kyleaudio
author_rank: Contributor
timestamp: September 17, 2016, 08:12:05 pm
content: Hi guys,I was recently given a broken 65" plasma smart TV. I replaced two shorted mosfets, a few bad caps and the fuse. The TV works great now!I got it setup in the living room and soon found out that when the TV was on, the remote controls for my other AV equipment started having problems, especially my surround sound receiver.After some troubleshooting I have come to the conclusion that the light emitted from the picture on the TV is what is affecting the remotes. The brighter the picture on the TV, the worse the problem. If I put a blanket over the front of the TV, everything works fine. Maybe the TV flickers at a rate that blocks the IR from the remotes somehow?When the TV is on, both remotes for my surround (main remote and zone 2 remote) are basically useless and my Verizon cable box remote acts as if the batteries are low. However the remote for the TV continues to work perfectly fine.I pulled apart the remotes for the TV and the surround receiver to compare, but I haven't come up with anything. The chip used in the TV remote is an ADAM24P20G and the IR LED is light purple in color. The chip in the surround remote is a Samsung 3F80JBBZZ-SO9B and the IR LED is very light blue, almost clear in color.Anyone have any ideas?Thanks,Kyle

author: SeanB
author_rank: Super Contributor
timestamp: September 17, 2016, 08:27:51 pm
content: No real quick fix, other than the simple one of putting the affected boxes further away from the TV set, and having a separation so they cannot be influenced by the IR light the plasma emits in operation, plus reducing the effect the high RF field produced by the set in operation might have on them.otherwise simply adding a light shield ( a small cardboard tube ( TP roll inner sprayed matt black as a quick try) attached to the front of the equipment where the IR reciever window is might attenuate the light enough to enable reliable operation.

author: bitslice
author_rank: Frequent Contributor
timestamp: September 17, 2016, 08:50:48 pm
content: turn the brightness down,you might have to compensate by closing the curtains or something.otherwise it's a known problem apparently

author: edpalmer42
author_rank: Super Contributor
timestamp: September 17, 2016, 09:11:47 pm
content: I didn't know there was such a thing as a plasma smart TV. I didn't think they had smart TVs back then. In any case, I agree with bitslice. Check the brightness. Stores tend to crank up the brightness as much as possible so that a TV looks great in their brightly lit stores. Most people don't know that when they get the TV home, they should reduce the brightnessa lotto get a proper life-like picture.If you really do have a plasma set, it's critical that you reduce the brightness. If you don't, you'll burn the screen.There are skilled people & companies who will come to your home and set up your TV for the best possible picture. For a plasma TV, the adjustments are more extensive than for an LCD TV. It'll probably cost a couple of hundred $, but for a 65" set, the results will be amazing!Ed

author: Buriedcode
author_rank: Super Contributor
timestamp: September 17, 2016, 09:35:30 pm
content: I don't know how savvy you are, or what parts you have to hand, but a photodiode with a simple trans-impedance amp and a scope would allow you to see if there's any 36,38,40kHz being kicked out. I know plasmas are generally noisy anyway but its pretty clear you've narrowed it down to optical rather than radiated noise. It'll also be handy to check the remotes to see what carrier they use - the ones that work, just at shorter range most likely use a different carrier that's close enough to the interference for it to be bothered, but not so close its completely swamping it out. IR modules tend to not be that selectivive - a 36kHz module will easily pick up a 38kHz carrier.Failing that, an IR receiver module (that has the photodiode AGC amp, detector etc..) built in would give you a yes/no.

author: TheBay
author_rank: Unknown
timestamp: September 17, 2016, 09:44:54 pm
content: White sticky paper labels places on the IR Receivers inside the devices worked for me when I had a Plasma.

author: kyleaudio
author_rank: Contributor
timestamp: September 18, 2016, 12:35:58 am
content: Yes, it's definitely a plasma tv. It's a Samsung model PM64E550 made in May 2012, not too old.I have tried moving the surround sound receiver and it works if I'm not pointing the remote to the front of the screen. If I put the remote to the side facing to the right/left, it works fine. But then I'd still have to get up from the sofa to adjust the volume!I've tried turning the brightness down and even at the lowest brightness and lowest cell brightness, the surround remote still doesn't work.I've tried a toilet paper tube and tried blocking light from above on the remote and it doesn't seem to help much. Even if I put the remote less than an inch away from the IR receiver, it still doesn't work.I tried to check the carrier frequency, but it wasn't easy to get a clear signal on my old analog CRT scope. From what I can see, they all look similar.

author: edpalmer42
author_rank: Super Contributor
timestamp: September 18, 2016, 12:56:34 am
content: Are the TV, receiver, and cable box all lined up and pointing in the same direction? Is there something shiny (glass, metal, maybe plastic) or just bright white on the opposite wall that the light from the TV can reflect off of and get back to the other receivers? If so, try covering that.Ed

author: kyleaudio
author_rank: Contributor
timestamp: September 18, 2016, 01:15:58 am
content: yeah, everything is lined up and pointing in the same direction and there is a window right behind the sofa. I just hung a dark color comforter in front of the window to completely block it, but it didn't make any difference.

author: kyleaudio
author_rank: Contributor
timestamp: September 18, 2016, 02:11:26 am
content: Well, I just put a piece of masking tape over the sensor on the surround receiver now the remote works much better! Very strange fix, but it seems to work. It seems like TheBay got it!Thanks for the help on this guys!