Wiring a DPST illuminated switch 5 pin.

Thread Starter

Chefslot

Joined Sep 24, 2018
28
I've got an old 240v t20 rocker switch that I'm sure had a jumper going to the 5th pin. Obviously looked for the datasheet online or other switches like this but the one I have managed to find has been discontinued and now it appears they all use 4 pins.

pin label

2N 5L
1N 4L
3? 6(blank)

The pin 3 is the one I'm confused about.

Regards
 

Thread Starter

Chefslot

Joined Sep 24, 2018
28
None are double pole single throw, which would normally give 4 terminals, pin 3 is the 5th. Is it for the lamp? I think I've had a switch before that needed to be jumped to enable the lamp to work.
 

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geekoftheweek

Joined Oct 6, 2013
435
Have you tried to connect the switch to anything? Is there resistance between pin 5 and any other ones? My guess would be a remote feed to power the light instead of the switch itself powering the light.
 

Thread Starter

Chefslot

Joined Sep 24, 2018
28
Have you tried to connect the switch to anything? Is there resistance between pin 5 and any other ones? My guess would be a remote feed to power the light instead of the switch itself powering the light.
Good call, no continuity one any off the other terminals no matter what state the switch is in. So I guess wire it up and see if it lights!!

Cheers
 

Tonyr1084

Joined Sep 24, 2015
4,710
Wouldn't suggest running forward with power just yet.

1) it could be an LED with an internal resistor
2) it could be an LED without any resistance
3) it could be an incandescent bulb
4) it could be burned out
5) pin 3 could be a ground lead for the light
6) it could be a Neon bulb

Assuming the possibility of an LED, you don't just check for continuity between pins. You have to check each possible connection twice; once with the red test lead on pin 3 to all other pins and once with the black test lead on pin 3 to all other pins. The meter should be in diode check mode. And if there's an internal resistor - I don't know exactly how that will affect the meter reading. I suppose I could bodge a resistor and LED together and see, but this isn't my problem.

Assuming an incandescent bulb - if there's any connection, testing with a volt/ohm meter will quickly show its presence. Unless it's burned out. Then it will be always open.

Assuming it's a Neon bulb - you won't be able to test that with a meter. It will require a voltage of typically around 70 volts (AC or DC). Now you're getting into the realm of potentially hazardous voltages. Be careful when testing with high voltage.
 

Thread Starter

Chefslot

Joined Sep 24, 2018
28
Tony thank you, will have a look into this. The neon bulb I doubt as there was nothing to change the voltage attached to it, but I do like your other suggestions, thank you!
 

Tonyr1084

Joined Sep 24, 2015
4,710
With 240 VAC, an LED would require one heck of a resistor to keep the current down. It would also need a standard diode in series to block the high voltage when the AC swings the opposite way. So I would tend to discount an LED. A bulb - to illuminate a switch - that would have to be a very special bulb, capable of handling that much voltage without a whole lot of watts. High watts means high heat, and could melt the plastic. IF it's made of plastic.

The best assumption might be a Neon lamp. They take very little current to light; and with a high resistance, the wattage would be quite low, and the neon lamp would still light up.

If you can't determine, via a meter, which points are for the lamp then determine exactly what all other points do with regards the switching action. Once you know all that you can, by process of elimination, determine which pin(s) cause the lamp to glow.

If you take pictures of the switch others will be able to better help you. Also, a listing of what you figure out as to which contact points are "on" when the switch is in a particular position and which are "off".
 

Thread Starter

Chefslot

Joined Sep 24, 2018
28
OK, I took the cautious route of testing it with a little solder wire, it breaks at low amps and it stays put aha. First I tried pin 1 to pin 3, stood back, flicked the switch with a broom handle..... Nothing. Then tried pin 4 to pin 3 and it worked!! Just in case someone else is in the same boat, but I can not confirm this will work for you.
 

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