TM 5-6675-318-14
Function
8
9
16
17
54
56
59
94
230
231
245
237
Displays contents of selected memory locations in octal notation
( r e f e r e n c e p a r a g r a p h e n t i t l e d “ D i a g n o s t i c I n d i c a t o r s ” ).
Displays contents of selected memory locations in decimal notation .
S t a r t s s e l f - t e s t .
T e s t s d i s p l a y .
Displays 400 MHz receiver oscillator frequency and S/N ratio.
Displays reference oscillator offset from 400 MHz.
Displays modem status.
Displays 150 MHz receiver oscillator frequency and S/N ratio.
Turns on modem.
Turns off modem.
Controls power override .
A b o r t s s e l f - t e s t.
f .
D i a g n o s t i c I n d i c a t o r s.
The error codes displayed by codes 16 and 50 isolate
malfunctions to the board or major module level.
To help isolate errors beyond that
level, diagnostic indicators are set within the microprocessor memory (Table 4-23).
g .
Code 8 is used to examine the diagnostic indicators in memory. The diagnos-
tic indicators are stored in consecutive memory locations, beginning with memory
address 142000 (octal) and ending with memory address 142017 (octal). The diagnos-
t i c i n d i c a t o r s a r e c l e a r e d t o 0 0 0 ’ s a t t h e b e g i n n i n g o f e a c h s e l f - t e s t . T h e y a re
lost when the MX 1502 is shut down or placed in standby.
h.
The diagnostic indicators shown in Table 4-23 have a separate diagnostic
indicator associated with each error code displayed by codes 16 and 50. Due to the
l e n g t h l i m i t a t i o n o f t h e d i s p l a y , a l l e r r o r s m a y n o t b e s h o w n . T h e r e f o r e , an
examination of consecutive memory addresses is recommended. Examine the diagnostic
error memory block as follows:
(1) Enter code 8 to examine the diagnostic indicators in memory. The diag -
nostic indicators are stored in consecutive memory address, beginning
with memory
address 142000 (octal), and ending with memory address 142017 (octal). A reading
of 000 at any consecutive address, indicates that there are no entries at succeed-
ing addresses.
The diagnostic indicators are cleared to 000’s at the beginning of
e a c h s e l f t e s t .
They are lost when the satellite surveyor is powered down or placed
in STANDBY.
(2) Refer to Table 4-23 to interpret the displayed octal number. A 000 or
177 indicates that no error has been diagnosed.
A 145, for example, indicates that
the 400-MHz satellite receiver board cannot lock onto the test frequency.
Troubleshoot the system in accordance with Table 4-24, which is keyed to the
error codes found in Table 4-23.
A f t e r e a c h c o r r e c t i v e a c t i o n , p e r f o r m s e l f - t e st
(paragraph 4 - 6 . 2) .
Table 4-24 shows a step-by-step procedure to isolate a malfunction to a
printed circuit board or other field replaceable assembly.
Table 4-23 lists several
indications of troubles that may be encountered, with the probable cause of each.
E r r o r c o d e s f r o m t h e s e l f - t e s t w i t h c o r r e c t i v e a c t i o n a r e a l s o l i s t e d .
4-192
Change 3
Code
i .
j .
