T.V. Remote Question

[fictitious]

Over the past week or so I noticed that my TV remote was less responsive than it should be . I took the cover apart and noticed that the rubber pad with the buttons on and also the top of the circuit board had some sticky substance on ...almost certainly from some spilled sugary tea recently . I washed the upper cover and the rubber pad and cleaned off the stickiness from the circuit board and now it is doing what it should be doing . I wondered however ,how these things actually work . When you press the buttons it obviously bears down on the relevant part of the circuit board but can someone explain exactly what is happening when you do that to cause ,for example,the channel to change....all that seems to be happening is that the underside of the button is pressing on the contact on the board.

[Jeff Lawrence]

Basically, when the button touches the contact it completes the electrical circuit for that particular function.

[Ed]

you just complete the relevant circuit programmed to transmit the relevant frequency.

[fictitious]

Thx..Now I understand .

[JNugent]

And just a quick addition...

The deposit on the upper surface of the buttons is unlikely to cause lack of response. That is more likely to be due to a dying battery.

[fictitious]

I changed the batteries a few days ago and the problem was still there. .I took the remote apart today ..washed off the stickiness and it now works like it should so seems very likely that was the problem.

Maybe I didn't make it clear but the stickiness was not only on the underside of the buttons but was on the area of the circuit board that the buttons contacted

[Jethro]

Many years ago, I had a similar situation. I opened the case and found a film of condensation over the circuit board and rubber contacts. I presumed many hours of being held caused it to get covered in water .....

[Mark A]

Had exactly the same problem with an Echostar satellite remote. The 'Select' and the 'Down' button had some liquid just where the button bears down on the contacts on the motherboard. I simply wiped it clean with a cotton bud (and off the underside of the buttons) and the remote started functioning like new again. I was quite pleased with myself.

Regards

Mark

[michael adams]

And yet another addition...

The deposit on the upper surface was dried tea. As the OP explained. When the tea was wet, as it will have been at one stage otherwise it would have been difficult to drink, it seeped through the gap between the buttons and the casing where the little buttons go through the little holes. That's how his circuit board got sticky.

HTH

michael adams

...

[Bartc]

The stickiness seemed to be grease when I sometimes took these apart. Perhaps body oils? I don't know how that would permeate through the rubber pad.

To change the channel.... the conductive underside of the rubber button completes a circuit, it causes an infrared data stream to be emitted from the LED. The TV picks this up, decodes it, and if you're lucky the channel will change (my own remote is very temperamental in this regard).

If you turn on a digital camera, look at it's screen, and point the remote at the lens, you should be able to see the LED flashing when you press the buttons (it's normally invisible).

[Dave Plowman (News)]

And sugar in the tea makes things worse - it's a reasonable conductor.

[Anton Gÿsen]

The thin circuit board part can become oxidised and corroded. You can clean it with a pencil eraser. I have done this on computer keyboards, I assume that remote controls have a similar circuit board.

[fictitious]

Yeah.It did seem to be a bit oily....could it be something the manfrs put on there to ensure a good contact and I have mixed it with the sugary tea spillage? .

[A.Clews]

And if you're unlucky it might do something with another appliance. The remote control 'volume up' button for my Marantz CD player would not only increase the output volume on the CD player itself, but would also cause the volume control knob on my Arcam amplifier to turn (and thus to increase the amp volume). Annoyingly, the Marantz r/c's 'volume down' button had no effect on the amp, but would turn the CD player's gain down, so one could get terribly confused :-)

Needless to say, the Marantz's r/c has lain in a drawer for some years ;-)

[Jeff Lawrence]

I had a remote control for a TV once that starting running the bath upstairs whenever I tried to change the contrast and flushed the toilet if I wanted to view teletext. Weird! Cheers Jeff

[Arfa Daily]

Many years ago, I had a similar situation. I opened the case and found a film of condensation over the circuit board and rubber contacts. I presumed many hours of being held caused it to get covered in water .....

It's an absolutely standard problem which all remotes suffer from, and is nothing to do with spillage or condensation or whatever. It is caused by the synthetic conductive rubber contact lozenges on the undersides of the buttons, breaking down chemically. Sometimes, they are recoverable by cleaning, but sometimes, it's just time for a new remote ...

Arfa

[Harry Bloomfield]

The rubber face is conductive and completes the contact of an etched gold contact on the PCB. That then signals the processor inside the remote to produce a preset series of on and off flashes of an Infra Red LED diode. Each sequence is different, depending on the button you press.

If you point the remote at a camera (digi or security type etc.) in a darkened room, you will probably be able to see the flashes from the remote on the camera's monitor.

[Jeff Lawrence]

You are Bartc's twin brother AICMFP. Cheers Jeff

[tomScotland]

So its *you* who's responsible for TV going down the crapper, eh? Hmm

[JNugent]

Ah...