Hi. Quite a few people wanted me to do a teardown of this little pain in the ass button that failed on my Aircon system. I'll link in the video if you haven't seen it. It was rather interesting and it has a dodgy contact in it.

It varies anywhere from like you know, a couple of like it should be like almost zero. Ohms? really? Um, but it varies anywhere from a couple of ohms even if you press it really hard, up to many hundreds of Ohms. And it caused a major problem if you design your switch matrix in such a way that it uses a single pin on your microcontroller and then analog to digital converter switches in different resistance values in the uh, pull up resistor in a resistor divider in this uh case. and it's a neat way of course to uh, sort of an age-old way to get multiple switches onto a single pin of a microcontroller or over one line.

In this particular case, like you can do it over one line and stuff like that anyway. Um, it's a neat way to do it. But the downside of course is that if this switch develops any high internal resistance due to wear, corrosion or whatever, then you're going to come with gutsa and it can. In this particular case, on my Aircon unit, this is the on off button that failed.

Um, and it actually because it failed at a couple hundred Ohms. In many cases, it would actually simulate appear as though other buttons were actually being pressed. So I pressed the on off button and my aircon to change from heating to cooling mode for example. And yeah, it's just a really fascinating insight.

So a lot of people said they wanted to see inside this switch. Now, I don't know. So let's zoom all the way in with my tagano and here it is pretty good. This is not digital zoom.

this is all optical zoom by the way. Um, and a lot of people wanted to see inside this. I'm not sure how much we're actually going to be able to see in inside this thing that on the sides, probably my, uh, soldering iron getting the thing off. so don't worry about that.

But uh yeah, it doesn't look the best is it? It's just a it's just a one hung low job. I think. um, so I wouldn't be writing home to my mum about that. but uh.

anyway, I thought we'd uh, tear it down and see what's what. We may or may not see something. I suspect it's just, uh, corrosion. A lot of people because you know, pesky oxygen in the air and all that sort of stuff.

A lot of people, uh, said that. I just swear, squirt some contact cleaner in there and it'll last for another decade if they're corroded. Not really. It might fix it for, you know, a little while.

Um, but then you're eventually going to come Agatha. So anyway, um, I'm not sure I've never opened one of these tactile switches. Um, so I like, maybe can we get in there and maybe slice off? Is that a way to? Is that a way to do it? I don't know. if you've got a full proof way of doing this.

please let me know. Um, I'm winging this one. So let's let's zoom out a bit there so if my blood gushes out of my finger, you'll be able to see it. So let's go.

It's I've got my spongy mat under here. you can really see my. This is the one that came with my togano microscope. I assume it's like Esd.

Well, it does have an Esd point on it. Yeah, it's definitely an Esd map. Um, but I haven't actually got it connected. Naughty Dave.

Anyway, uh, let's okay. So oh, there we go. There we go. It just popped off right? I thought I'd have to force that, but nope.

So oh there you go. All right this is. this is going to be interesting. Ah, let's lift that up.

Oh yeah, Oh yeah, that looks like corrosion doesn't it? Oh, that's the. that's the snap dome on. Sorry, no that's the that. That's the snap dome on top.

There you go. So it just looked like rust. But uh. anyway.

I've never seen a is that an accurate color? It looks like yeah, that's an accurate color. What you're seeing on camera here. it's like it's hard to get the lights right and everything it's all to do with the exposure and lights and whatnot. Anyway, that yet the plunger.

Yeah, that'll have a little knob in there and well let's see if our disk falls out yet. Yeah, yeah, there we go. There we go. That is our corroded disc.

You can definitely see that there is corrosion on both. the snap dome yeah you can really see the corrosion in there where it makes. Con: where the center of the disc center of the snap dome makes contact. so if we flip that over, that should still that should still give us a snap.

Yeah, there we go. You can see it deform like that. That's why they call them tactile switches because they're based on these tactile domes. They can be different shapes.

They don't have to be around like that. I've done videos going through. I've got a kit um of different ones. There we go.

that's the best zoom I'm going to get on the Tagano microscope. Not bad considering 30 centimeters working distance. Look at the working distance of this thing. you can see the bottom contact in there, the so the edge contacts over there which uh connect to the dome.

I don't think they're the issue because the side of the dome looks okay so like the the edges are probably alright. but yeah there you go. center of the dome and that switch. so that's causing hundreds of ohms um even if you let you press really hard.

the best I could get on it was like a couple of Ohms I could not wear as a brand new freshy. You know it's down in like the tens of millions range right there. They're really quite low. but uh yeah, there you go.

So I was surprised that we actually got to see something decent in that not much in is it. that's a real cheaper construction. One might be interesting to, uh, crack open a different type. I can do that All right.

Let's get my kit of switches here. I can assure you these are the cheapest possible. One hung low quality because these are like a kit that came on ebay for like you know, two bucks delivered for the whole kit. Just worth having, right? So these will be the absolute crappiest quality.

I've got the same size switch there so let's chop this one open and have a look so I wouldn't expect this one to be any better at all. It just looks just looks a bit fresher. That's all. There you go.

Yeah, it's still got, you know, like it's not going to stop any crap getting into it. I don't know. are any good quality ones any better? Does anyone know? Sorry I don't I've probably I could probably get a good quality one if I look through some of my project kits like a known good quality Alps or something. But there you go.

There you go. We're in there. you go. It's got a different color, snappy dome, but it looks almost identical.

Doesn't it The oh, there you go. There you go that's inside a cheap He hasn't corroded yet. Um, does that have the ring? And that one's got a center ring around the center? like a ring around the center contact. Is that is that what they're using as the contact in there? whereas the other one didn't have that only had the single center contact? So quite a significant difference.

There you go. Quite a significant difference in the designs there. Which one. whether or not they're using that center contact.

Oh, you could buzz that out. Yep. Yep. So that that outer ring is actually connected through to that inner one.

and then these outer bits here will be connected to the pin over here. Yep. So yeah. so there you go.

That's all one. So I guess there's uh, possibly two contact points on that one there where as opposed to whereas we had a single one there and it didn't really have a dimple in it did. It didn't really have a dimple, it was just a flat contact. Whereas this one is actually look, oh yeah, look at that.

you can see that's really poking up there and I can. I can feel that too. Okay, yeah, that one's really got a raised surface. So that one's very different.

so it's never going to contact that outer ring. so I'm not sure what's doing there. So yeah, there you go. There's a significant difference between those two designs right there.

And yeah, that's uh, corrosion. I'm not sure you would, uh, get rid of that just by spraying some stuff in there to probably help you know if you needed to get out of trouble spraying it with some gunk and it easily get down the shaft or in the side or whatever. It's probably easier just to go down the shaft really and then squirt the whole thing. That'd help and get you out of trouble for a bit, I suspect, but not going to get that off in a hurry.

Still going to be there. So yep, that is corrosion I suspect. Is that just poor plating? I don't know any plating experts out there, any metal urges in the audience. There's always someone who knows what does that look like.

Is that like a coating? I mean, obviously there's some wear issue there. Check that out. That's a good shot. some wear issue.

but yeah, those larger patches on the side. they definitely look like corrosion, don't they? So please leave it in the comments down below if you know about your metals and your corrosions and stuff. Okay, I do actually have a known brand here. We've got a C and K, one of the uh, best brands out there, but this is one of their like low end ones I think and I looked up the data sheet uh for this and they don't specify the material on it.

You know it's got a hundred thousand lives, a lot and there are switch actuations or whatever. Um, a hundred millions initial on resistance so it's nothing special. I think this is just their bare bones, but it is a Cnk, so let's crack open a Cnk. It looks very similar, doesn't it? No.

Like the construction is exactly the same, but the inside could differ substantially so, but I suspect not. You know, we've probably just got a, you know, a Phosphor bronze contact or something like that. Plated and uh, silver of course is a common. uh, that one's just not that one's not popping off without a fight.

Is it all right? There we go. So anyway, usually they're like a stainless steel top. You can get a stainless steel material switches and there you go. That one could be a stainless steel, but it looks very similar to the one we had over here.

Does it? Ah yeah, I can't see huge, so that is that like a nickel plate? Or is that like a brushed stainless? I'm not sure. I'm not sure because it doesn't actually tell you. So there's your, there's your dome and there's your contact. they've just got.

Oh, that's a bit different. It's got a split in it. Look at that. It's got two contacts.

That's interesting. So there you go. So that would likely be a silver plated. yeah I did that that that looks silver plated to me.

but once again, any metal urges out there I can tell just by looking at it. but um of course silver is silver corrodes. Um so yeah. but that that's interesting.

see that's got like a dual. You know I call that a dual wipe kind of contact. There's nothing else in the dome. the dome is just the dome.

There's no like a little nipple in it or anything. I like a good nipple. And of course you know changing the geometry of the dome and everything changes like the tactile force and the tactile feel. And you know everything.

There's actually uh, performance curves. You can get a good good data sheets for real uh to high-end switches will give you like the performance. uh curve. You know if you go get like your snapdragon domes and things like that.

Therefore, as I've shown in previous videos, they're like fully characterized and stuff. But there you go that's inside of Cnk. So interesting. That's at least three reference points for you.

I think I like. You know the Cnk looks the bet. I mean that contact. Like just having the dual contact in there, I can really feel that you can see that raised up.

I really like that one. That's really nice. Um although this one in the ebay cheap. I mean this ebay cheapie.

It looks that you know it. Just the plating on That looks cheap, right? It looks cheap as compared to the Cnk one. right? Look at that. Cnk on the left.

Ebay Chippy on the right. It's got all sorts of hairy, scary stuff inside the ebay. Cheapy, doesn't? It doesn't look that great. So, but you know that one's raised up.

It's oh, it's actually. yeah. It's got a hole in the middle. You can really see that now.

That's pretty good. Wow. Anyway, there you go. That's the difference.

Any of you are switch aficionados out there are really into this sort of stuff. Please leave it in the comments down below what your opinion is as the three switches there. There you go. Switch aficionados let us know your thoughts.

Down below: Cnk Ebay cheapy in the middle, and then on your right you've got the uh, the failed corroded one with a couple hundred Ohms. But that's you know, possibly the end life of, uh, most. you know if you get like a silver plate or something like that. Unless you get like a high quality, uh, gold, uh, plate one? Uh yeah, it's silver corrodes.

You know, nickel I guess. Um, corrodes as well. You get nickel plating ones and stuff like that. So yeah, sure, there's lots of Switch if aficionados will fill us in in the comments.

Anyway, hope you liked that video. If you did, please give it a big thumbs up because that was rather interesting. So thanks to everyone who suggested I do that, I thought it'd be boring. It's not.

This is interesting. Damn it. Catch you next time you.