Query Regarding Earphones

[Old_Geezer]

Earphones that I use with my mobile & tablet suddenly failed on the right side. Flexing the lead suggested the issue was with the plug, which doesn't seem openable without destroying it. So I decided to order a stereo 3.5mm plug and try to replace the original.

So far so good, except when it arrives I see the pin is divided into 3 (which seemed reasonable) yet comparing to the original I see it's pin is divided into 4.

Why is that, are there 2 returns ? How does that gel with there seemingly being just 2 wires ? (As I write this I now notice only one wire goes to the earbud, surely it must have 2 in each  even though it looks too thin.)

Also, is it something to do with the unnecessary stop/start switch in the right side wire(s) ? Have I just wasted money on the new plug and need to accept that earphones have a short lifespan ?

(Background: the wired one was bought because the Bluetooth one I already had not only started to fall apart, the volume differed each side so I was already disappointed with wireless.)

 

TIA

[Electrochem]

The original probably had a built in microphone, hence the extra connection:

https://www.circuitbasics.com/how-to-hack-a-headphone-jack/

[Old_Geezer]

Thanks for the link. Can not see a mic, just the switch, but maybe that's how it tells the the video to stop & start.

[netherfield]

Having just ordered an item from viking, along came a free gift, logilink stereo headphones set. Full headphones and small bud type earphones all in the same box. The earphones have the 4 connection plug with a small switch on the lead, the head phones only have a 3 connection plug, both work equally well when plugged into my computer. Although the switch does absolutely nothing in this case.

The two connections furthest from the tip on the 4 plug seem to be shared on the 3 plug.

[Old_Geezer]

Thanks. Having compared the two plugs I thought that may be the case.  I've not hacked it yet. I don't really want to be without some earphone facility while trying to get it right, even if it's just the left side. I may buy a cheap earphone as a temp one before starting the operation.