Electronics > Beginners
How to diagnose always active button on a remote control
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Saco:
Hello,

I have a typical rubber-dome TV remote where I'm facing the opposite of the "normal" problem. Instead of a button not working, I have a button that is always active.

Even after removing the rubber-dome panel and having only the PCB exposed, the button is still always active (I can see that, because when I put the batteries on, the TV LED keeps blinking. Only stops when I remove the battery).

I tried cleaning it several times with Isopropyl Alcohol and contact cleaner to no avail.

How should I go about fixing this? I am on a complete loss as I don't see anything that captures my attention.

I have attached a picture of the PCB and a close up of the circuitry area in case it's relevant.

cvanc:
Can you re-post your photos with a circle around the button location that gives trouble?

Also, here's a handy tip for troubleshooting IR remotes:  Most cell phone cameras can see "just enough" IR to see the pulsations of the IR LED at the top of the remote.  This is a Very Useful Thing some days  :-+

Good luck with your repair.
Twoflower:
Careful about the cell-phone cameras. That worked in the past. But newer ones might have a very well working IR cut-off filter. I fried one IR diode trying to get it working. My iFruit 4s main cam didn't see anything but the 'selfie' cam showed the IR-LED working. But as the secondary cams get better with later generations they might fail to see IR as well.

One way would be first to try a working IR remote to test if the cam can see it or not.

If you have a RasPi (or similar) you might get a universal IR receiver (e.g. TSOP31238) and get lirc up and running. Lirc might be able to tell the command that's transmitted.
wraper:

--- Quote ---I tried cleaning it several times with Isopropyl Alcohol and contact cleaner to no avail.
--- End quote ---
But have you cleaned IC? I see something that looks like dirt on corrosion on it's terminals.
Saco:

--- Quote from: cvanc on November 17, 2018, 06:20:16 pm ---Can you re-post your photos with a circle around the button location that gives trouble?

Also, here's a handy tip for troubleshooting IR remotes:  Most cell phone cameras can see "just enough" IR to see the pulsations of the IR LED at the top of the remote.  This is a Very Useful Thing some days  :-+

Good luck with your repair.

--- End quote ---

I can’t tell for sure what is the problematic button as all I know is I see the TV LED blinking. I assume it is the power button (top right corner) as the screen does not power on but I don’t know.
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