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MNEMONIC
SWC
SWR-L
SWON-L
SWS
TERR1-L
SIGNAL
Servo
Write
Current
Servo Write
Switch On
Servo Write
Select
Timing
Error 1*
Functional Description
7936 and 7937
Table 5-1. List of Mnemonics (20 of 23)
SOURCE
Il1II
A2
[IIA1
(Ii
A1
Ii D 1
A2
[II A1
DESCRIPTION
WRITE CHAIN output which sends current
to the SERVO READ PREAMP/ WRITE
DRIVER IC when dedicated servo code is
written on the dedicated servo surface.
(Factory use only.)
SWC is connected to the SERVO READ
PREAMP/WRITE DRIVER IC in HDA A3
via HDA cable WS.
SERVO CONTROLLER Servo Control Bus
handshake
line
to
SERVO
CONTROL
INTERF ACE in controller PCA-A6.
When
active, SWR-L indicates that the SERVO
CONTROLLER is driving the bus with a byte
of status information.
SWR-L is connected to controller PCA-A6
via read/write PV A-A2.
AMPLIFIER
CONTROL
and
FAULT
INDICATION output. SWON-L controls the
input signals to the servo power amplifier in-
put stages.
WRITE CHAIN output which selects the
operating
mode
of
the
SERVO
PREAMP/WRITE DRIVER IC. SWS is low
when read is selected, and approx. 3.5V when
write is selected. (Write mode is only used
when the dedicated servo code is written at
the factory.) .
SWS is connected to the SERVO READ
PREAMP/WRITE DRIVER IC in HDA A3
via HDA cable WS.
DEDICATED SERVO TIMING and PLL
output to FAULT LATCHES.
TERR1-L
represents an overall timing error caused by
Start of Sector gap not occurring at the
proper time relative to SMDT-H.
TERR1-L can be monitored at pin 5 of the
servo test point PCA.
5-67
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