Grounding issue

[Demious]

Im having a grounding problem with one of the Seymour Duncan pickups in my strat. When I touch the A-string pole of the neck pickup in 4th (middle+neck) position, I get a serious increase of hum, which doesnt happen when I touch any of the other poles. The middle pickup is an SSL-3t rwrp and the neck pickup is an STK-S6.
When I touch the A-string pole, together with the strings/bridge/any grounded item, the hum stops. In 3rd (bridge+neck pickup) and 5th (neck only) position, this same effect happens with all pole pieces from the neck pickup, what confuses me. The other 2 pickups are fine in all positions.

To me this seems a grounding issue, though Im not very familiar with electronics, but Im a little confused about the effect changing from one single pole in 4th, to all poles in 3rd and 5th position. I went over my schematic and all ground wires seem to be connected correctly and I tested all wire connections with a multimeter and there are no failing connections. However, when I measure from the pole pieces from the bridge pickup (Little 59) to ground, I see they're connected, but this is not the case with both middle and neck pickup.

Does anyone recognize this behavior and can tell me anything that could help me locate the problem?

[DavidRavenMoon]

Re: Grounding issue

On Strat pickups the start of the coil (black wire) should connect to ground. This is because the inside winds are against the magnets. So if it were hot you’d hear a hum. So grounding that end of the coil sends that noise to ground.

Now assuming that the middle pickup is wired the right way, it could also be a sign that there’s a short in the coil against one of the magnets.

What happens if you touch the string to that magnet?


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