Keithley 7077 Instruction Manual page 20

• The Model 707 Switching Matrix
is shipped with its backplane row
jumpers installed. Some configu-
rations require these backplane
row jumpers to be removed. The
procedure for removing these
jumpers is in the Model 707 In-
struction Manual.
• The Model 708 Switching Matrix
does not have backplane row
jumpers. It is a one-slot switching
matrix.
Backplane compatibility considerations
The Model 7077 may be incompatible with other card types
when expansion is through the backplane. For example, in
some test systems it may be necessary to connect LO of the
Model 7077 (which is a two-pole card) to LO of a three-pole
card. As shipped, the Model 7077 backplane row jumpers
connect the LO signal paths to the GUARD terminals of the
three-pole general purpose backplane of the Model 707 or
708 switching matrix. The LO signal paths of the other card
are connected to the LO backplane terminals of the Model
707 or 708. With this configuration, LO of the Model 7077
cannot be routed to LO of the other card.
The Model 7077 provides flexibility by allowing the back-
plane route of the guard signal paths to be altered. The back-
plane row jumpers are shown in Figure 2-7. They have circuit
designations W125 through W140. The odd circuit designa-
tions (W125, W127, W129, W131, W133, W135, W137 and
W139) identify the LO jumpers of the card. These jumpers
connect the LO signal paths of the card to the GUARD back-
plane terminals of the Model 707 or 708. Adjacent to each HI
jumper (identified by the even circuit designations) are holes
in the pc-board to accommodate a jumper. By moving the
guard jumpers to these locations, the matrix card LO paths
will connect to the low backplane terminals of the Model 707
or 708.
WARNING
Internal modifications to the matrix
card should only be performed by quali-
fied service personnel familiar with
standard safety precautions.
CAUTION
Solder operations require that the pc-
board be cleaned. Refer to the precau-
tions contained in paragraph 4.2.
NOTE
G
ROW A
H
G
ROW B
H
G
ROW C
H
G
ROW D
H
Model 7077
G
ROW E
H
G
ROW F
H
G
ROW G
H
G
ROW H
H
Figure 2-7
Backplane jumper configuration (factory default)
A simplified schematic diagram of the Model 707 backplane
is shown in Figure 2-8. The segmented line represents back-
plane connections for one matrix row. Each empty slot is iso-
lated by the open backplane connections. Row connections
from one slot to an adjacent slot are accomplished through
the jumpers on the Model 7077 Matrix Cards.
Model 707
Backplane
Slot Slot Slot
1 2 3
Figure 2-8
Model 707 backplane configured for row expansion
Operation
L
W125
G
W126
H
L
W127
G
W128
H
L
W129
G
W130
H
L
W131
G
W132
H
To 3-pole
general purpose
backplane of
L
W133
Model 707 or
G
W134
Model 708
H
L
W135
G
W136
H
L
W137
G
W138
H
L
W139
G
W140
H
Slot Slot Slot
4 5 6
2-7