Tandon TM-100-1 Operating And Service Manual page 40

When the disk drive is selected, the activity (front panel) LED will be on.
In a multiple disk drive system, the MX jumper must be cut. If not, the disk drive will always be active.
Circuit Description
R14 holds the output of the appropriate select line high until the line is driven low. This is buffered through IC 3E
9-to-8 to IC 3D 9-to-8. IC 3D, Pin 8, is the output that enables the drive electronics. Note that when the MX jumper
is not cut, the disk drive is always enabled (Pin 3D-8 high).
The front panel LED is driven by the select logic through IC 3E, Pin 3 to 4. Note that if the disk drive is not selected
through the select jumpers, and the MX jumper is not cut, the drive electronics will be active but the front panel
LED will not be on.
Normally, Tandon Corporation's disk drives have no head load solonoid . Hence, the HS and the HM jumpers are
nqt used. In no case should both the HS and the HM jumpers be in since this would allow interaction between the
Select signal and the Motor On signal. However, if the optional head load solonoid is installed, IC 2C, Pins 1, 2, &
3 drive it. This is selected by either the HS or the HM jumper. The HS jumper enables the head load solonoid driv-
er when the unit is selected. the HM jumper enables the head load solonoid driver when the Motor On signal to the
disk drive is true.
3.3.1.2 Drive Motor Enable (N MOTOR ON)
Functional Description
When the Drive Motor Enable signal line logic level goes true (low), the disk drive's motor accelerates to its nomi-
nal speed of 300 rpm and stabilizes in less than 250 msec. When the logic level goes false (high), the disk drive's
motor decelerates to a stop.
Test Point 13 (see Figure 3-4) is low (true) for the Motor On condition.
J1
16
N MOTOR ON
Circuit Description
15
TP1
150
2F
2
+5V
+5V
R19
1K TP13
J4 P13
~ - - - - - - - - - - - - : - - - - i 2 5 1 N MOTOR ON
+12V - - - 3 1 4 MOTOR POWER
.---------i30 3 MOTOR GROUND
Figure 3-4
Drive Motor Enable Schematic Diagram
The disk drive's Motor On signal comes in on Pin 16 and is buffered through IC 3E, Pin 1 and Pin 2 to·the servo
board.
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