©
National Instruments Corporation
C-1
SCB-68 Shielded Connector Block User Manual
C
Fuse and Power
One of the +5 V lines from the DAQ device (pin 8) is protected by an
800 mA fuse. Pin 14 is also +5 V, but it is not fuse-protected on the
SCB-68. Shorting pin 14 to ground blows the fuse, which is usually
socketed. If the SBC-68 does not work when you turn on the DAQ device,
first check the switch settings, then check both the 800 mA fuse on the
SCB-68 and the output fuse (if any) on the DAQ device. Before replacing
any fuses, check for short circuits from power to ground.
A 470
Ω
series resistor (R21) filters the +5 V power on the SCB-68. As the
fi5 V is loaded, the voltage decreases. Pad R20 is in parallel with
R21, and you can install a resistor if needed. Shorting R20 bypasses the
filter while capacitively coupling DGND and AGND, and this
configuration is not recommended.
Caution
NI is
not
liable for any device damage or personal injury resulting from improper
use of the SCB-68 and the DAQ device.
Refer to Figure 2-1,
SCB-68 Printed Circuit Diagram
, to locate the fuse
and other components on the SCB-68. A suitable replacement fuse for the
SCB-68 is made by Littelfuse
and has part number 235 800.
