Output Modules
TTL 8 kHz Clock Output Module
270
TSG-3800 User’s Guide
12778474-002-2 Revision F – March 2004
Table 7-45
describes the TTL 8 kHz Clock Output module front panel status
indicators (LEDs).
Functional Description
Refer to
Figure 7-22
for the following functional discussion. The module accepts two
reference input signals (A and B) from separate Frame Generator Modules. The
module selects one of these signals (normally A) and applies it to two drivers. Each
driver supplies 10 square wave outputs in a TTL format.
If reference signal A fails, the module detects its loss and switches to reference
signal B. The processor can also switch references.
The module checks the outputs to confirm signal presence. Should an output fail,
the front panel OUTPUT FAULT indicator lights.
Power A and B on the main shelf provide power to the module. These redundant
sources of –48 vDC are diode-coupled and fused, allowing the module to draw
power from either source. The internal fuse labeled F1 protects the circuitry from
excessive current. The DC-to-DC Converter changes the negative voltage into +5
vDC; the green POWER indicator on the front panel is lit when either power source
is available to the module. The POWER indicator turns off when power is lost, for
example if the fuse on the module opens, if both –48 vDC power inputs are lost, or if
the converter fails.
Table 7-45. TTL 8 kHz Clock Output Module Status Indicators
Indicator
Color
Description
POWER
Green
On = The module is receiving power.
INPUT FAULT A
Amber
On = No reference signal applied to input A.
INPUT FAULT B
Amber
On = No reference signal applied to input B.
OUTPUT FAULT
Red
On = Output failure on one or more channel.
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