Radio Shack TRS-80 Service Manual page 103

5. Check for debris or foreign material between the
heads and remove same.
RESISTOR TERMINATION
(See Figure 2)
6. Check plastics for broken or cracked pieces,
e.g., write protect lever, guide rails, etc.
NOTE: To ensure proper operation of the Drive, the chassis
should be connected to earth ground. The 3/16-inch
(4.76 mm) male QC lug, located at the rear of the chassis, is
provided for this connection.
1. The Resistor Termination in the IC socket is used
in the last drive in the system only. It must be
removed for Drive two when two external drives
are used.
Note: The internal drives in the Model III are not
term inated.
MOUNTING THE DISK DRIVE
The Drive can be mounted in any plane, Le. upright, hori-
zontal or vertical. However, when it is mounted horizon-
tally, the Logic PC board side of the chassis must be the
uppermost side. Tapped holes are provided in various loca-
tions for the attachment of user·supplied hardware.
"
"
3'
32
30
28
26
"
2 2
20
18
16
,.
12
10
8
6
•
2
Jl
~D,
RESISTOR TERMINATION
liN SOCKET!. REMOVE EX·
CEPT FOR LAST DRIVE IN
SYSTEM.
'0'
"
,
FIGURE 2. RESISTOR TERMINATION
FLAT RIBBON CABLE ASSEMBLY
(See Figure 3)
2. Connector for second internal drive (Drive one)
and second external drive (Drive three). pins 10,
14 and 32.
Pins must be removed from Drive connectors on the Cable
Assembly as follows and as illustrated:
1. Connector for first internal drive (Drive zero) and
first external drive (Drive two), pins 12, 14 and 32.
DRIVE DRIVE DRIVE DRIVE
NUMBER ZERO NUMBER ONE NUMBER TWO NUMBER THREE
'2
,.
12
I.
"
,.
" "
32 32
J2 J2
FIGURE 3. CABLE ASSEMBLY - CONNECTOR PIN
REMOVAL CHART
96