In an (ultimately successful) effort to solve the problem with my wife’s cordless phone handset (it had become increasingly unresponsive over time to pressing the buttons), I followed the instructions in this video.
I took off the keypad, just like the guy did at 2:12 in the video, and found that all of the contacts (both on the flexible pad itself and on the circuit board beneath) were contaminated with an amber-ish oily substance. Thinking that perhaps this fluid was impeding the conductive pellets from making contact with their target sites on the board, I sopped up all of the fluid with toilet paper, and wiped it off the board, after which I reassembled the handset and tested my work.
As I stated above, I was successful, and the phone is now responsive to the keypad. I AM curious, however, to know what the substance was. I’ve considered and discarded the idea that it was sebaceous oils from anybody’s facial skin, or in fact ANY fluid that originated from outside the handset. My reasoning is that if the stuff came from outside the phone there’s no plausible reason for it to end up between the keys and the board.
Are there any manufacturing engineers on the Dope who might know (I’m beginning to suspect that over time it naturally seeps out of the materials that the keypad is made of, and that eventually I might do well to obtain and install a brand-new keypad)?
As always, thanks in advance for knowledgeable responses!
Likewise, I’ve occasionally dismantled older electronic items (years ago when they weren’t necessarily old), like telephones, and found globs of yellowish greasy glop inside them, like axle grease. I’ve also wondered what that was all about.
Sounds kind of like soldering flux, but that shouldn’t be on any finished product, and would be all there from the start, rather than building up over time.
Other than that, it could be plasticizer leaking from the keypad itself over time (which tends to happen with a lot of old or cheap plastic or rubber materials).
I’ve seen the same thing, and I guess it comes from the keypad material; as for solder flux, I have seen plenty of stuff that wasn’t cleaned of solder flux and it appears as a hard solid brownish substance, most noticeable when desoldering parts (cleaning isn’t necessary with many solders since the flux only acts when heated/melted; of course, you’d want it cleaned off a keypad PCB).
Also, since it is likely coming from the keypad, repeated cleanings will only go so far since the keypad will become stiff and brittle, turn into mush, or just fall apart, so you’d eventually want to replace it (although by then I’d think you’d get a new phone).
We really LIKE this phone, and have no desire to obtain a different one (this one is discontinued, and Panasonic has nothing current with the same features).
I’ll see if I can find a kit to replace the keypad.
I’m heavily involved with manufacturing of cell phones, and take them apart quite often. I’m not aware of any useful reason to include an oily substance like what you describe in the process..which makes me think it’s something that has either leached in (oil from the skin, liquid spilled on the phone, etc), or something that has leached out of the material.
-D/a
When I was working in cordless phones, it was attributed to facial oils. It was predominantly associated with keypads that came in contact with the face.
I might add that on my keyboard, the liquid appears most on the keys used most often. So it might be skin oils diffusing through the silicone, or pressure/heat related.
Makeup residue maybe? I also wouldn’t put it past kids to spill something on the phone and do a quick and incomplete cleanup. As long as it still works, why tell Dad. If it is one handset of a multi-phone system you could check the other handset to see if it has the same residue.
I wonder if human skin oils can really stay liquid long enough to accumulate to such an extent; vegetable oil turns into a sticky, then hard, residue (definitely not something you can just sop up with toilet paper) in a relatively short period of time because unsaturated fats are relatively unstable and prone to oxidation (this is used to advantage in oil-based paints); even saturated fats, which are solid at room temperature, are nowhere near as durable as synthetic oils.
