The Yamaha SG-2 introduced in 1966, was one of Yamaha's first solid body electrics. Released alongside the SG-2 was the three pickup SG-3 version as well as the shorter scale 12-string SG-12. The SG-2 (AKA model S301 in Japan) has two single coil pickups. The control circuits appear rather complicated at first - according to SG-3 owner Gavin Wilson of the guitarz blog the SG-2 has two circuits (rhythm and lead) so you can set up two different tones on the guitar and switch between them,. The volume and tone controls on lower part of the guitar work in the usual way for the main circuit, but the switch nearest the point of the upper horn allows you to select the alternate circuit which has separate volume and tone “wheels” just above the neck pickup.
Yamaha described this model as follows in a promotional brochure for the US market:
"This Yamaha Electric Guitar Model SG-2 is extremely popular with both the solo and rhythm players. Tonal quality may be changed from solo to rhythm with the ﬂick of a switch. Complete range of tonal selection is available in either the solo or rhythm settings. The pre-set toggle switch allows instant changes from one pick-up to the other or a combination of both.The new Anisotrophic Ferrite Magnets in each pick-up assure a consistent tone at all levels of volume. The roller type bridge is fully adjustable to meet the individual player’s requirements. A ball bearing action tremolo arm provides the performer with a soft touch movement that returns to the accurate pitch after use. The neck is made of select maple and is adjustable for easy regulation of the fingerboard action. The scale is 25.5”. The body contour is shaped to form a comfortable playing position. High gloss polyester finishes are available in three popular colors at no additional cost: Coral Red. Pearl White. Sunburst. Chrome plated individual machine heads have modern designed metal buttons. Overall Length: 41” Width: 13.75” Price: $229.50"