How do toggle switches work?

[mockingbird]

I've got a board here with a switch, it's got a three pin switch... The AC adapter is low mA and 20 volts. I can't seem to get any voltage past the two DC pins from the AC adapter port that are soldered in the board...

Now the positive pin on the back of this relatively simple board travels to one of the three pins of the switch. My understanding is that when the switch is toggled, it connects the first and second pin (I don't know what the third pin is) and the secnd pin is jumpered to the rest of the board somehow...

...yet whether the switch is toggled or not, I'm only reading 20V when the probe is on the first pin of the switch...

Is the switch defective?

I ask because the board doesn't power up, no voltage even before the the small either tantalum or ceramic capacitor near the two mosfets.

Here is the datasheet of the exact switch:

It's the switch pictured at the very top right corner.

[Mad_Professor]

Re: How do toggle switches work?

They are essentially throw switches. If you add a magnetic coil or solenoid and run current through them they become relays.

what model?

It will tell you in the data sheet what function it does when the switch is in a position?

Remove it and do a continuity test on it.

I've had broken switches before, so it's not uncommon. The springs and slide plates wear out, and they get stuck in the wrong position.

[ratdude747]

Re: How do toggle switches work?

funny, I just had an spdt switch I bought DOA on me today. yes, switches do break, and break often.

[mockingbird]

Re: How do toggle switches work?


So the voltage is only showing on the first pin of the switch (The shortest one). The way I understand how this switch works, is that when it's switched on, it jumpers the first and second pins together, and the second pin passes on the voltage to the rest of the PCB. So should I just jumper the shortest and middle pin to see if the switch is broken?

[joshnz]

Re: How do toggle switches work?

I included a image to help you visualize.

[mockingbird]

Re: How do toggle switches work?

Ah, beautiful... So it is just jumpering... So as suspected, since the second pin is getting no voltage in the ON position, the switch is probably dead...

Question... Why have a third "NO" pin for OFF? Why not just leave it not jumpered? Is this for continuity of ground when the AC Adapter is plugged in and it is off?

[joshnz]

Re: How do toggle switches work?

I believe they connect the unused pin to The pcb for support as for them been connected together more pad = more strength.
As far as I can see it has no other benefit.

[mockingbird]

Re: How do toggle switches work?

Great... Newark seems to stock these switches... Now it's just down to getting the exact same one... Ouch, $5 for a switch?

[joshnz]

Re: How do toggle switches work?

yea switches can be costly I shop round.

[cmj21973]

Re: How do toggle switches work?

QUOTE=mockingbird;195649]Great... Newark seems to stock these switches... Now it's just down to getting the exact same one... Ouch, $5 for a switch?[/QUOTE]

Ususally the sliding/rocking contact gets fouled with gunk or fried from arcing.

Depending on the switch's size and if you can't take it apart, it's best to pay $5 and save yourself some trouble.

Or, you could scavenge/recycle a switch from something else.

P.S. Just seen the datasheet for your switch. Epoxy filled = toss when broke