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TM 55-4920-412-13&P
r.
Digital Display Board (A12).
(1)
Set Power Switch to ON and set controls
on unit tester as follows:
(a)
Inter Cal Select Switch to 21.
(b)
Display Update Switch ON.
(c)
Analog Set Switch to STOP then
SLOW, then FAST.
(2)
Set Power Switch to OFF. Inter Monitor
will count up displaying 1827 and then reset. If not, see
troubleshooting Table 4-36.
NOTE
Isolation of defective monitor boards
NO 1 (A7) and NO. 2 (A8) requires a
known good signal data converter
(SDC). If monitor boards do not pass
performance
tests,
substitute
a
known good SDC. If they still do not
pass send the VIDS test set, along
with the known good SDC, to the area
TMDE support team (ATST).
Table 4-36. Troubleshooting Digital Display Board (A12) Units, Tens, Hundreds, Thousands, Update, Inhibit Circuits.
NOTE
Use extender board as applicable when troubleshooting circuits.
Trouble
Probable Cause
Remedy
Analog Monitor does not count up
Digital Display Board (A12). Regula-
Replace defective components or re-
displaying units digits 0 thru 9 and
tor Board (A4). B C D Counter
place boards. See figs. 4-14, 4-18,
reset.
Boards (AS). Analog Processor (A9),
4-19, 4-21, 4-22, FO-6, FO-8, FO-11,
(A10). OSC Board (A6) (Reset
FO-12, FO-13, FO-14.
Pulses).
Analog Monitor does not count up
Digital Display Board (A12). Regula-
Replace defective components or re-
displaying tens digits 0 thru 9 and
tor Board (A4). B C D Counter
place boards. See figs. 4-14, 4-18,
reset.
Boards (A5). Analog Processor (A9),
4-19, 4-21, 4-22, FO-6, FO-8, FO-11,
(A10). OSC Board (A6) (Reset
FO-12, FO-13, FO-14.
Pulses).
Analog Monitor does not count up
Digital Display Board (A12). Regula-
Replace defective components or re-
displaying hundreds and reset.
tor Board (A4). B C D Counter
place boards. See figs. 4-14, 4-18,
Boards (AS). Analog Processor (A9),
4-19, 4-21, 4-22, FO-6, FO-8, FO-11,
(A10). OSC Board (A6) (Reset
FO-12, FO-13, FO-14.
Pulses).
Analog Monitor does not count up
Digital Display Board (A12). Regula-
Replace defective components or re-
displaying thousands and reset.
tor Board (A4). B C D Counter
place boards. See figs. 4-14, 4-18,
Boards (AS). Analog Processor (A9),
4-19, 4-21, 4-22, FO-6, FO-8, FO-11,
(A10). OSC Board (A6) (Reset
FO-12, FO-13, FO-14.
Pulses).
Update Rate Control Input 5 Vp-p
OSC Board (A6).
Replace defective components or
missing from pin 2.
board (A6). See figs. 4-16, FO-4,
FO-10.
5 vdc low or missing
Logic Power Supply (A3). Input 8v
Replace defective components or
missing to Regulator Board (A4) or
replace boards (A3), (A4). See figs.
output 5v missing.
4-13, 4-14, FO-6, FO-7, FO-8.
4-66 Change 2
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