IBM 3270 Maintenance Manual page 423

The right drive is a diskette drive. Check the
voltage between the pins shown below.
Right Drive Power Connector
Min Vdc MaxVdc
-Lead
+
Lead
+
4.8
+
5.2
2 4
+
11.5
+
12.6
3 1
Type 2 Diskette Drive
ARE THE VOLTAGES CORRECT?
NO Replace the power supply. See Section 5,
"Removal/Replacement and Adjustments."
YES
3-9999-18 Maintenance Information