Download 1 - NSCA TRA-CAL

The SWITCHING THRESHOLD VOLTS indicator and mainframe crt readout
display indicate a self-test failure with a numeric code. All of the self-test code
numbers are listed in Table 2-1, along with the nature of the failure and an
explanation of the severity of the failure. The severity information is helpful in
determining if the 7A42 can still be used for the intended purpose or whether
repair is necessary. To continue the self-test sequence, press any of the 7A42
front-panel pushbuttons.
NOTE
There should be no connections to the RESET EXT CLOCK, and TIP inputs
during the time Self Test is running.
NOTE
Before the 7A42 Self Test feature can verify that the 7A42 readout circuitry is
operating properly, mainframe crt readout system must be set to the "Freerun"
(non-Gated) mode.
I
I
DISPLAY MEDIA
I
I
TYPICAL DISPLAY
TRIGGER FUNCTION LEDS
GREEN = TEST PASSED
RED = TEST FAILED
0
SWITCHING THRESHOLD
VOLTAGE MONITOR
(Numerlc Dlsplq)
LEVEL
Q
SWITCHING THRESHOLD
VOLTS
CRT READOUT
(Numerlc Dlsplq)
NOTE: Durlng some self
tests, the crt reedout Is
unstable; this condltlon
Is normal.
'
FAILURE
NUMBER
Flgure 2-11. Typlcal self-test fallure display.
2-50
REV JUL 1984