Brother DP-550CJ, Service Manual

Page: 60 / 194

THEORY
Electrical
SERVICE MANUAL
2-24
10. FDD (Floppy Disk Drive) Control
10.1. FDD Configuration
The FDD consists of two sections: the FDD controller and the FDD module. The FDD
controller circuit controls the contents to be received and stores the data in the FDD
module. The FDD module drives the motors, sensors, and magnetic head. The
interface signals between the FDD and the FDC are shown in Table below:
Table.2.3 FDC(#5) and FDD Module Links (Interface Signals)
Signals Pin No. Function
Read/Write
Circuits DRIVE SELECT Ø 10 12
This signal is set to LOW when the FDD unit is
opening (except for the DC Motor).
WRITE GATE 24
When this signal is set to LOW, data can be written
by the WRITE DATA signal. When this signal is set
to HIGH, the READ and STEP operations are
enabled.
WRITE DATA 22 Data is written at the falling edge of this signal while
the WRITE GATE signal is LOW.
READ DATA 30 This signal indicates the polarity data read by the
head.
SIDE1 SELECT 32 This signal is used to select the head:
LOW: Head 1
HIGH: Head 0
Motor Drive
Circuit DC
MOTOR MOTOR
ON 16 This signal becomes LOW, starting the DC motor,
when a disk is set in the drive. Setting this signal to
HIGH or removing the disk stops the DC Motor.
STEP
MOTOR STEP 20
This signal sets the head in the direction designated
by the DIRECTION signal.
DIRECTION
SELECT
18 This signal designates the movement of the
read/write head:
LOW: Inward to the disk's center
HIGH: Outward from the disk's center.
Status Check WRITE PROTECT 28
When this signal is LOW, either there is no disk in
the drive or the disk in the drive is write-protected.
INDEX 8 This signal indicates the beginning of a track by
outputting one pulse in each rotation of the disk.
TRACKØØ 26 When this signal is LOW, the head is located at track
00 (the outside track).
Otherwise, the signal is HIGH.
DISK CHANGE 34 When this signal is LOW, there is no disk in the drive.