Printed Circuit Board Operation; Introduction; Physical Description Of The Circuit Board; Interface Electronics Specifications - Tandon TM848-1 Operating And Service Manual

SECTION III
PRINTED CIRCUIT BOARD OPERATION
3.
INTRODUCTION
This section contains the interface description and the circuit board theory of operations for the
TM848 family of disk drives. In addition, Sections 3.1 and 3.2 contain schematic diagrams of the
circuit boards installed in the drive.
3.1 PHYSICAL DESCRIPTION OF THE CIRCUIT BOARD
The printed circuit board is approzimately 12.50-inches long by 5.25-inches wide. Figure 3-1
contains an illustration of the placement of test points and connectors.
R133
M18
0
g
M2
a:.
00 P6 P14
o
ffitttttttttffl
00
00
a:CIl
a:c
~P4
~P5
M3
0-0
OM4
2SCH)
DC 00
00
RI
v
TP11 0 0 TP12
ALTERNATE TEST POINT. INDEX TRIGGERING
~I
NP
ooy
OS1
S
g & S 2
WP
TP5
t
TP4000pT6
P2 P3 P10 P1 P11P12
~
TP2
TP1
!
o
~O
TP3
00081
1b 0
000S2
2b 0
000S3
3b 0
00084
4b 0
P8
pg
9iffftttff
o
OTP8
OTP10
gOL
P7
00
P13
Figure 3-1
Printed Circuit Board
3.2 INTERFACE ELECTRONICS SPECIFICATIONS
All interface signals are TIL compatible. Logic true (low) is +0.4 volt minimum. Figure 3-2 illustrates
the interface configuration. The maximum interface cable length is ten feet.
+
5V
+ TRUE
r--------,
I
I
I
I
I
I
I
L
7~6 ~~E~U~~~~
TWISTED PAIR
TRANSMISSION LINE
~ 10 FEET
74LS04 OR EQUIVALENT
+ TRUE
DRIVER
RECEIVER
Figure 3-2
Interface Configuration
3-1