Seagate BARRACUDA ST11950N/ND/W/WD - Manual (Page 35)

ST11950 and ST12550 Installation Guide, Rev. D 33
For W- and WD-type drives, use pins 11 and 12 on the
J5 connector to attach the spindle sync cable. Pin 11
provides the reference index signal (REFSIG
+
) and pin
12 provides ground (GND). See Figure 12.
DC Power
Connector SCSI I/O
Connector
Spindle sync reference index signal
(REFSIG+).
Spindle Sync Cable Connector (SSC)
These pins are used to connect a
spindle sync cable.
Ground (GND).
J5 Pin 1
SSC
J5
Figure 12. Spindle sync jumpers and connectors
for ST11950W/WD and ST12550W/WD drives