SG Pickup info from the SG Graffiti book (thanks to Youkokuramafan)
This is translated directly from the book. Listed are the main models:
1976 – 1983
SG500 used the least detailed and cheapest pickup, called the G-III
SG700 (and later the SG600 and SG800) all used the same “step-up” pickup from the G-III, called the G-II
Not much more information is given on those pickups…those were Yamaha’s “cheap” pickups.
SG1000, SG1500, SG2000 all used the same Alnico V pickup.
This pickup is the model OPG-I. There are two variances, the OPG-I and the OPG-II. The only differences are the OPG-I has gold pole piece height adjustment screws, while the OPG-II has chrome pole piece height adjustment screws. The OPG-I costed 6,000yen OEM, while the OPG-II costed 5,000yen OEM.
1982 – 1998
In September 1982 the first SG-3000’s were made. This also marked the debut of the Spinex pickup, made from Yamaha’s own custom material.
In 1983 many variances of the SG models were made, most of these also used the new Spinex pickup.
From 1983 – 1998 some SG-1000, SG-1500 and SG-2000 models were also ordered with the Spinex pickup. Some still with the OPG-I.
Production of the Spinex pickup stopped. All models after this went back to the Alnico V pickup.
However the model number of the OPG-I changed to the SGH-1CB, many people refer to this as the “New OPG-I”. The base plate of the “New OPG-I” is no longer made of real brass like the original OPG-I, instead it is made of nickel silver. Also, the year of manufacture and model is no longer stamped on the “New OPG-I”. They are just stamped “SG”