Newbie question on power switch

[senderj]

I bought a switch kit but I wrongly soldered it. I have to unsolder almost all components to redo it. I guess I might have damaged some of them while unsoldering. As a result, I got AC out regardless of whether the switch is turned on or off. I attach the circuit here.

Without connecting to AC in, I checked any possible short circuit in the relay, the cap and the PCB, and they are all normal. With AC in but S1 off, I found that both legs of the cap, the middle leg of the relay and AC out has power. The relay seems ok since when switching on S1, I can see the relay flip to the other side. Does it means the cap is not working? Please help.

[AndrewT]

Hi,
I think your circuit is OK.
The cap is there to reduce pitting in the relay contacts due to sparking when breaking the switch.

Without a load connected the cap will allow a very small mains signal through and when measured with a high impedanace DMM will look like AC on.

Try connecting it to a mains rated load (light bulb or unconnected transformer). This should pull the AC out down to neutral when OFF and then rise to full AC volts when ON.

I do not know how your mains wiring is regulated in HK, but you show a ground symbol where I would normally show the return/neutral/cold. Here ground is a third wire in the cable back to the distribution board.

[senderj]

Thank you for your reply. I understand now. All my checking were done without loading. That's why there is always an output.

The gnd symbol is my mistake. You are right that it should be N.

Thanks for your help.

[AndrewT]

Hi,
36 hrs and no corroboration?

I hope I'm right!

[senderj]

AndrewT,

Sorry I don't know what did you mean in the last post. Can you explain?

The switch now works very well in my system. Thanks again.

Senderj

[AndrewT]

Hi,
I was worried that my interpretation could be incorrect.
I was hoping that someone else would confirm my thoughts.

You have now confirmed that it is working Ok.

Maybe I was right - thank goodness.