hi, i just soldered a 5 way switch into my strat 3 coil.

all the 5 settings work ok with 1 being bridge only, 2 bridge & middle, 3 middle only, 4 middle & neck and 5 neck only.

the problem is there is quite loud hum in positions 1, 3 & 5. in 2 & 3 when two pickups are blended there is no hum at all

any idea what might be up? i put copper shielding into the cavities and tested that with a multi meter and it has continuity.

the volume and tone control are functioning fine

thanks very much for any advice
Copper shielding is only part of the equation. Star terminating your returns helps also, prevents ground loops. Did you do this also?
Well unless they are noiseless singles, they are going to have 60 cycle hum. The middle one is reverse-wound, which is why 2 & 4 dont hum. It's acting as a humbucker when either neck or bridge is paired with the middle.
hi guys, thanks for replying.

so they are supposed to hum? it's just very loud, especially when i use effects. i measured the pickups using a multi meter and i think they were all around 6.5 - 7.

i don't know what star terminating is. i soldered it according to a diagram with loads of ground wiring.

it's a bit messy
sorry for the late reply. Each pickups rating sounds about right, and as best i can tell the wiring looks correct too. Singles just like to hum, and any chance there is for that to multiply (high gain, effects, etc) they are just going to.
hi charley2715, no problem, thanks very much for filling me in regards the normality of hum. i'm looking at a site that describes how to cancel out a lot of hum on a strat. not read it yet but hopefully i can find the proper ingredients and it's not too difficult
you need to shield the whole cavity including the backside of the pickguard to make a completely shielded enclosure around all the electronics. you only shielded one half of the electronics.

and secondly star terminating or star grounding is where you have all the groud points go to a single central location i.e. all the grounds go to the back of the volume pot.
The photo shows the setup isnt star grounded. Your grounds connect from one pot, with a nice big jumper link to next pot, another jumper link to the 3rd pot, which is linked to input socket in a nice big loop and then linked to your pickups. This creates an 'antenna', which is great for picking up mains hum

'Star' grounding has all your grounds (including the bridge chassis ground lead) connect back to a common point, be it the back of one pot, or the ground terminal of your input jack or something similar.

If you put copper shielding on the back of your pick guard then all the pot chassis will be connected together automatically via the conductive shield, and you can connect your input jack ground, pick up grounds, etc all back to an arbitrary central point on this without any need to provide additional ground wires for the pots and switches

something like this combined with the all over shielding (which Brentonlatour touched on) may help in completing the equation to alleviate some hum before assuming that you just need to live with the hum.