Re: New to Seymour Duncan pickups...Ibanez/Duncan wiring issue.
Nice going on the 520, those are sleepers of the late 90s Ibanez line.
How are you trying to wire it? As per stock switching?
The Ibanez switches work the same way as US CLR types, just that the Ibanez ones have all their terminals in a row as opposed to four per side.
Here's my old 320, which has the same wiring as the 520. Green encased wires are bridge pu, red encased are neck.
Left to right: white end from bridge (I swapped around the white and red here to get an out of phase sound in mix pu positions); neck hot (equivalent to black on Duncans); neck end; volume control; bridge hot (see first comment); then the black is ground for the switch. The bare grounds of both pups should go to the pot casing - I did a sloppy job here as they weren't long enough

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So, If you want the stock wiring: replace the red wire of the Ibanez pu with the black of the Duncan; the white of the Ibanez with the red/white together of the Duncan; and the bare of the Ibanez with the green/bare together of the Duncan. Remember that in the pic I've got the white and red of the bridge swapped for out of phase, so unless you want that, do it the other way around.
I'm fairly sure this should work, maybe some of the other wiring geniuses here can affirm/correct me

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