Mixed pickups in my Epiphone Les Paul

I was given an Epiphone Les Paul 100. It has the original humbucker at the neck but a Schecter humbucker at the bridge. The three-way switch only works in two positions, middle and left. The original Alnico Classic (I'm assuming that's right) has one wire whereas the Schecter has four. Please point me in the right direction to successfully wire them to work. Thanks.

The original pickup with a single wire will actually have 2 connections, it probably has a shielded wire with a metal braid that is the second connection. The centre conductor normally connects to a lug on the volume pot and the braid connects to ground by being soldered to the back of the pot. With the 4 wire pickup two of the wires will need to be joined together (and the connection insulated) and the remaining 2 wires would then connect to the volume pot (one to the appropriate lug and one to the back of the pot). As to which wires need to be joined and which need to connect to the pot this will depend on the pickup as different manufacturers use different wire colour schemes. If you know what the pickup is you should be able to find the wire colour coding on the internet.

Awesome information. Thanks

From what I have found online, it looks like Schecters use Duncan Design pickups in some cases.
Looks like the Schecter "Super Rock" is a Duncan Design as well.
Try tying the red and white together, green to volume lug, and black and bare wire to ground.
Insulate red and white as already stated.

A few had USA Duncans: same color code as above

They also use EMGs... both active and passive styles (you probably don't have an active EMG, they use a battery)
The passive EMG HZ is wired: black and white tied together and insulated, red to lug, and green and bare to ground.

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