this isn't the video that I have planned for today but something came up so I'm
going to deal with it this is a little cooking thermometer that works pretty
well we've been using in the kitchen for quite a while however it recently had an
unfortunate meeting with the floor and now it doesn't seem to want to turn on
unless you push and hold the switch as soon as you let go of it it goes off so
I'm guessing that either the switch got mechanically damaged or the circuit
board got cracked when it hit the floor regardless you know the task has been
assigned to me to either make it work or replace it so I'm going to try and make
it work inside we have the probe with some kind of sticky goop I thought that
would be hmm I thought that would be rigid and whatnot but no it's actually
still sticky okay so two ways going down into the probe I don't know if that's
going to be resistive or a thermocouple but for now I see two screws and a
battery the tiniest screwdriver tip fortunately have a fairly large
assortment of them and have come with various different screwdrivers that I've
bought over the last few years normally what I'm doing a teardown I'm not too
gentle about it because I don't care if it goes back together this I do care
about hmm
okay those switches are cheaper than a thought they just short the two pads or
not okay so I think that is the power one it is and that is the Celsius
Fahrenheit 100 that's painless so all I need to do let's grab the little switchy
button guy here and pry up the wipers ever so slightly can it be that easy
well while we're in here let's look at what we've got we have an LCD it looks
like it's attached where there's one of the zebra stripes things you have a few
passive components oh I can see the BIC wouldest blob underneath there and then
another couple of resistors in a capacitor and then just the battery and
the temperature sensor on this side hmm no g1 and g2 are doing on the back of
their test points obviously actually you know wait a minute
those look like split pads that one is connected and that one is not connected
hmm some sort of options wonder what happens well I'm gonna reassemble this
quickly which is going to be fairly straightforward it should be I think
do I need to give that a little nudge to get it in that's not good although maybe
it'll help us so there's the LCD but knocked off its moorings I'm always so
scared of these zebra stripes because they always seemed like such freakin
magic down in there you that's tight so what was hiding underneath it then
nothing really surprising the mystery blob that's about it so what I don't
understand fully is how these zebra stripes get wound up what I'm hoping is
that it will line itself up just automagically when I put this back
together here maybe it is just the precise alignment of all these
components in this cheap injection molded case so let's see what happens
someone's on
Celsius Fahrenheit switch works that's still not working properly huh maybe if
I make these pads a little bit more three-dimensional okay there we go it's
on so it's just the Fahrenheit switches back to Celsius turns off turns on
that's what you want to see beautiful now then let's put it back together here
get the way is that nice little twist in there so they're not getting caught yes
it does work my coffees got cold while I'm doing this but that's okay it works
never would have expected that to be the problem that I'd have reassembling it
kind of thought it would be that silly zebra stripe thing I still don't know
how those things work apparently the official name for the zebra stripe
connector is an elastomeric connector and zebra stripe is actually a trademark
hmm never knew that consists in alternating conductive and insulating
regions in a rubber or elastomer matrix they excel in shock and anti vibration
applications okay they can even be act as a gasket that's
interesting could be carbon or silver or gold I'm guessing the black ones are
carbon probably and are used in to a spacing of rubber conductive strips
equals the PCB conductor spacing with precise alignment or the spacing of the
rubber conductive strips less than half the PCB conductor spacing so you don't
need precise alignment here's just a catalog from my guest from
the manufacturer conductive layer pitches low is 0.05 millimeters wow
that's that's crazy I'd seen these things before but I hadn't really looked
into them before so this is this is kind of fascinating actually
so carbon silver gold or what is FG s zero insertion force that uses
gold-plated well different pitch spacing conductive layers per me per inch up to
500 conductive layers per inch wow that's a superfine pitch so here's the
thing that the article was talking about the Wikipedia was talking about this
one's got a whole bunch of really narrow conductive and insulating strips each
one is narrower than the gap between the conducting strips so you don't get
shorts between the pads but as long as one or two of these lines up with the
pads above then it's gonna make contact yeah this is just one of those things
that I never knew a whole bunch about and boto all I knew about them was they
existed and they worked like magic now I know ever so slightly more but
this is another one of those advances in technology that's happened sort of in
the interim since I used to work on component level stuff decades ago and
know that I'm getting back into it again it's fascinating and just a little bit
scary oh here we go current carrying capacity per wire so
per conductive stripe 250 milliamps per max wow that's crazy
less than 25 millions per contact pad that at a hundred milliamps I'm gonna
put a link to this down in the comment there in the description just rather
than media is going through here and rambling about it
if you're interested feel free to take a look well that was a fascinating little
detour and hadn't expected to go on all because this thing got dropped on the
floor not the video is expecting to do today but what's life without a few
surprises once in a while thanks for watching
comments questions down below I will talk to you later