SRS Labs SR430, Manual, Page: 104 / 146

TEST AND CALIBRATION
Unplug all cables from the unit and recall the de-
fault setup by holding the [CLR] key down while
turning the unit on.
This test requires a simple TTL rate generator to
trigger the SR430. The rate generator output
should be attached to the TRIGGER input of the
SR430. The trigger rate should be variable up to 2
kHz. Set the Trigger Level and Slope to trigger on
the generator output.
The rear panel TEST output is used as the source
of signal pulses. The TEST output is a 50 Ω, NIM
level output at 50 MHz. The pulses are synchro-
nous with the BIN CLK and thus a known number
of pulses will occur within each bin.
Use a BNC cable to connect the TEST output to
the SIGNAL input on the front panel. Set the Dis-
criminator Level to -300.0 mV and the Discrimina-
tor Slope to Negative.
In the Mode menu, select a Bin Width of 40 ns and
set the Bins/Record to 1k. Set the Records/Scan
to 1000. Set the TTL rate generator to a frequency
of 1 kHz.
Press the [START] key to begin acquiring data.
The 1000 records should require 1 second to ac-
quire. The Status indicator should display Trigd
and BUSY for the 1 second. There should not be a
RATE error since the record time is 1024 x (40 ns
+ 250 ns) + 150 µs or 450 µs and the trigger peri-
od is 1 ms.
When data acquisition is complete, the Status indi-
cator should display DONE. Use the [AUTO-
SCALE] key to scale the display. In each record,
each 40 ns bin will count 2 pulses (the TEST pulse
period is 20 ns) and 1000 records will accumulate
2000 counts in each bin. The first bin is an excep-
tion. The first bin always counts one less than the
rest of the bins and so will have 1000 counts in it.
Use the display and cursor to verify that the data is
correct. If there is some variation from bin to bin,
that may be because the cable connecting the
TEST output to the SIGNAL input delays the test
pulses such that they always occur right on a bin
boundary. In that case, even though no counts are
lost, there will be some variation as to which bin
each pulse goes into. Use a slightly longer cable,
or add a short length of cable to delay the pulses
away from the bin boundaries. In either case, the
total number of counts should be correct.
Clear the data using the [STOP] key. Select a bin
width of 5 ns. Press the [START] key to accumu-
late 1000 records again. In this case, only every
103
POWER
To start, make sure that the power entry module
on the rear panel is set for the ac line voltage in
your area and that the correct fuse is installed.
The selected ac voltage may be seen through the
window on the power entry module. Verify that the
line cord is plugged all the way into the power en-
try module and that the power button on the front
panel is pressed in.
SCREEN BRIGHTNESS
If the screen is too dark or too bright, adjust the
brightness using the knob at the upper left of the
screen. Do not set the brightness higher than nec-
essary.
DISPLAY POSITION
Use the Setup Screen function in the SETUP
menu to position the display in the center of the
screen.
FAN
The fan in the SR430 is temperature controlled.
When the unit is cold, the fan is at half speed.
When the internal temperature reaches about 30°
C, the fan speed increases. Do not block the vents
in the chassis or the unit may not operate properly.
FRONT PANEL TESTS
The keypad, knob, disk drive, screen, and memory
may be tested using the Test menu. See the Test
menu section for a complete description of the
tests.
POWER ON RESET
If the instrument turns on with odd settings, an in-
correct or blank screen display, or is unresponsive
to the keypad or knob, then the memory contents
may have been corrupted causing the instrument
to "hang". To remedy the situation, turn the unit off
and hold down the [CLR] key while turning the unit
back on. This causes the unit to reinitialize the
memory and assume the default setup.
TESTING THE DATA ACQUISITION
HARDWARE (COUNTERS, MEMORY, AND AC-
CUMULATOR)