SF Fenders - Coiled White Wire

[RightLurker]

I've noticed in several pictures and videos of SF Fender amps that there are one or two thin, white-coated wires coiled around other wires in the chassis. One end of the coil of white wire appears to be connected to ground. What is the purpose of those white coils? Some sort of shielding, perhaps? Just curious. Thanks in advance.

[Firestorm]

Both ends are grounded, but in slightly different places (not far enough to induce loopy hum). They are intended as shields. The one wrapped around the B+ bundle coming out of the cap pan works. It suppresses 120Hz hum coming from those leads. The other one goes around the overly long tone control leads on the reverb channel. That one doesn't work so well. Kills some high end and leaves a trace of fizziness trailing notes. I always replaced that whole wire mess with double shielded three or four conductor cable (3, 4 conductor plus shield). Or you can move the caps to the pots.

[martin manning]

My first thought would have been that these things are acting like small capacitors connected to ground to prevent high frequency oscillations.

If they are functioning as shielding (coverage is poor, though), that might be a benefit for the tone stack wires, but the B+ wires would be a source of 120Hz hum, right? And, the small value of capacitance developed would represent a very high impedance at 120Hz.