EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: niconiconi on June 16, 2021, 08:17:35 pm

Title: How do I remove a (crimped??) thermal switch
Post by: niconiconi on June 16, 2021, 08:17:35 pm
Hi all.

As shown in the picture, I suspect this KSD301 thermal switch in a coffee machine is defective and I want to remove it for a check. But I don't see any solder on the joint, is it a clamped crimped connection |O? If so, is there a way to nondestructively remove the switch?

Note: in the second picture, the slot-like object is actually the end of the multistrand wire, it's not a connector slot.
Title: Re: How do I remove a (clamped??) thermal switch
Post by: Ian.M on June 16, 2021, 08:44:14 pm
You can't  non-destructively.  The wires have crimped on ferrules which are spot-welded to the switch terminals which in turn are riveted to the switch.

Connect a suitable test lamp (e.g. a neon indicator with integral series resistor) across the switch and try operating the unit.  If the test lamp lights up and the switch isn't over 95 deg C, its failed open and should be replaced.  If it doesn't light up, its probably still good unless you are certain the switch is over 95 deg C.

Repacement would involve cropping the wires right at the ferrules, crimping on female spade connectors aNd pushing them onto the lugs of a new switch.
Title: Re: How do I remove a (crimped??) thermal switch
Post by: amyk on June 17, 2021, 01:22:31 am
They are too cheap to even use female spade terminals like that part was originally designed for. :palm:
Title: Re: How do I remove a (crimped??) thermal switch
Post by: TheMG on June 17, 2021, 02:07:21 am
They are too cheap to even use female spade terminals like that part was originally designed for. :palm:

In these days of mass manufacturing and maximizing profit... every penny matters.

Just cut the wires off and crimp some terminals on there to connect the replacement, if it does turn out to be bad. As for testing... it's a switch, no need to remove it from circuit for testing. A DMM is all you need unless you suspect its temperature range is no longer accurate, then a thermocouple would be handy too.
Title: Re: How do I remove a (crimped??) thermal switch
Post by: BrokenYugo on June 17, 2021, 02:59:16 am
They are too cheap to even use female spade terminals like that part was originally designed for. :palm:

I'd rather they weld them, seems those switches are often killed by the spade connectors developing bad connections and heating the switch from the wrong end.
Title: Re: How do I remove a (crimped??) thermal switch
Post by: perieanuo on June 17, 2021, 02:16:02 pm
we can see the solder, just unsolder the pin
btw,, that thing when it breaks, it doesn't close anymore correctly his contact (so your ohmmeter will see more than 0.3 ohms), or it cuts off at wrong temp, the voltmeter will tell you the truth. can't really do repairing without them aren't we?