Can you help me understand this switch and find a replacement?

Thread Starter

rambomhtri

Joined Nov 9, 2015
397
Hi, I have a device (steaming iron with water tank) with 2 of these switches:
PXL_20210721_193015600~2.jpg

and 1 of these:
PXL_20210721_202714130.jpg

All 3 don't work very well, and the problem is I don't know where to find a replacement. I was thinking of AliExpress but I am not sure how to find a compatible one. Specially the last one, which seems to be very specific.

Also, I don't know how the first switch works. Why does it have 3 pins instead of 2 pins?
Why the V(AC) and current are printed?
Do they simply mean that with 125V it can safely handle only 6A, or 3A with 250V?
Maximum power of 750W... so then why that line with 10A 250V?

I know the first 2 switches are in bad condition, but in both I've only managed to find a short circuit between 2 pins. All other combinations (2 combinations) give open switch, doesn't matter if it's ON or OFF, that's why I don't understand why there are 3 pins. The steaming iron actually have 3 cables in both switches, so I assume I can't replace them with a 2 pin switch.

PXL_20210721_191832868~3.jpg

Thank you!
 

Ian0

Joined Aug 7, 2020
3,181
It looks like an illuminated switch to me. The third connection is the neutral connection to the neon.
https://www.rapidonline.com/marquar...-12a-ip40-spst-black-w-red-rocker-i-0-59-4055
You won't measure any continuity to the third terminal, as the neon will not conduct at less than 100V.

The other item is a V4 microswitch
https://www.rapidonline.com/camdenboss-csm40500a-3500a-button-solder-microswitch-78-2400

Is 750W the power of the appliance? If so then 250V 6A would be a very suitable choice of switch.
The ratings mean that it was approved for 250V @ 6A, and at 125V @ 12A by Underwriters' Laboratories in the USA*, and at 250V @ 10A at up to 85°C by some other approval organisation which has a "D" symbol

*Perhaps someone who recognises the symbol can confirm this.
 

Yaakov

Joined Jan 27, 2019
3,464
It looks like an illuminated switch to me. The third connection is the neutral connection to the neon.
https://www.rapidonline.com/marquar...-12a-ip40-spst-black-w-red-rocker-i-0-59-4055
You won't measure any continuity to the third terminal, as the neon will not conduct at less than 100V.

The other item is a V4 microswitch
https://www.rapidonline.com/camdenboss-csm40500a-3500a-button-solder-microswitch-78-2400

Is 750W the power of the appliance? If so then 250V 6A would be a very suitable choice of switch.
The ratings mean that it was approved for 250V @ 6A, and at 125V @ 12A by Underwriters' Laboratories in the USA*, and at 250V @ 10A at up to 85°C by some other approval organisation which has a "D" symbol

*Perhaps someone who recognises the symbol can confirm this.
Beat me by seconds, Ian. :)
 

Ian0

Joined Aug 7, 2020
3,181
I think the D in a circle is the approvals mark for Demko (Denmark). Once it is approved by one country in the EU, it is approved by them all, and I think that the Scandinavian countries charge less. Before the Treaty of Maastricht they were much more pedantic about inspection and approvals than the rest of Europe. It seemed a bit hypocritical as Denmark was still installing domestic lighting circuits with no earth conductor - probably that's why they needed equipment to be safer!
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
397
Thank you!!!

So, if I understood correctly, when you switch ON you close the path between PIN 1 and PIN 2 (current, actual work), but also between PIN 1 and PIN 3 (light). Is that right?

How did you know it was called "V4 microswitch"?

Now if I search that term in AliExpress I get plenty of results, fantastic!

No, sorry, when I said 750W of maximum power I meant (to ask) if the switch was designed to support safely 750W or not?
You know, I did 125V times 6A and voila. It is a question.
 

Ian0

Joined Aug 7, 2020
3,181
So, if I understood correctly, when you switch ON you close the path between PIN 1 and PIN 2 (current, actual work), but also between PIN 1 and PIN 3 (light). Is that right?
Almost - in the ON position it connects between 1 and 2. There is a neon lamp permanently connected between 2 and 3. So 1 goes to live, 2 goes to load and 3 goes to neutral. When it is on, the neon gets connected across live and neutral.
How did you know it was called "V4 microswitch"?
Without being facetious - because it looks like one! There seems to be V3 microswitches and V4 microswitches. V3 are bigger, switch more power and have two contacts at the end and the holes on a diagonal. I don't know what happened to V1 and V2.
Now if I search that term in AliExpress I get plenty of results, fantastic!
And some of them might actually work.
 

Thread Starter

rambomhtri

Joined Nov 9, 2015
397
Yeah!
About the V4 microswitch name question, I meant how do you know those are called V4 microswitch?

If you find a component, in this case we know it's a switch, how do you know the special name this switch has if it's not written or printed on it. I searched for 1/3hp switch without any luck.
 

Ian0

Joined Aug 7, 2020
3,181
Yeah!
About the V4 microswitch name question, I meant how do you know those are called V4 microswitch?

If you find a component, in this case we know it's a switch, how do you know the special name this switch has if it's not written or printed on it. I searched for 1/3hp switch without any luck.
Years of experience!
The little operating button makes it a microswitch
There are only two types of microswitch in general use. V3 and V4, and it's not a V3!
 
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