TM 11-5805-386-34/NAVELEX 0967-466-1020
Malfunction
Corrective action
Probable cause
common module
1A4C4 for short and inductor 1A4L4
and ACCESS push-
for open; replace, if defective. If
button on channel
they are not defective, replace common
module are
board 1A4A2.
c.
If signal is present at test point
pressed.
TP6 on common module, check dc
voltage at terminal E 11: if voltage
is not present replace common board
1A4A2.
a.
If signal is not present at test point
9. SERVICE REQUEST
570-Hz oscillator is
TP5 on common module, check capacitor
indicator light
defective.
I
1A4C1 for short and inductor 1A4L1 for
does not go out
open; replace if defective. If they
when plug is
are not defective, replace common
inserted into
board 1A4A2.
either channel
b.
If signal is present at TP5, check dc
jack.
voltage at terminal E 10 on common
board 1A4A2. If voltage is not
present, replace common board 1A4A2.
a.
If signal is not present at TP4 on
10. 4-wire sub-
Ringback oscillator or
common module, check capacitor 1A4C2 for
interrupter circuit
scriber(s) indi-
short and 1A4L3 for open; replace, if
defective.
cates ringback
defective. If they are not defective,
not received
replace common board 1A4A2.
when seizing
b.
If signal is present at TP4, check dc
channel.
voltage at terminal E8 of common
board 1A4A2; if voltage is not present,
replace common board 1A4A2.
b. Trouble On Any One Channel.
Corrective action
Malfunction
Probable cause
2250-Hz detector on
Lift receiver from TA-341 (*)/TT to apply
1. NIGHT ALARM and
channel module analog
seize signal, then measure voltage at TP4;
SERVICE REQUEST
board or seize latch on
if voltage is over 3 volts, replace logic
do not operate.
logic board defective.
board A1A2; if voltage is less than 1
volt, replace analog board A1A1.
a. Check lamp; replace, if defective.
a. SERVICE REQUEST indicator
2. SERVICE REQUEST
indicator does
defective.
b. Replace logic board A1A2.
not operate, but
b. Logic board A1A2 defec-
NIGHT ALARM does,
tive.
3. 570-Hz acknowledge
a. ACCESS pushbutton
a. Press ACCESS pushbutton and check
tone not heard
continuity; replace, if defective.
defective.
after pressing
b. Logic printed wiring
b. Replace logic board A1A2.
SEIZE and ACCESS
board A1A2 defective.
pushbuttons.
Replace logic board A1A2,
DTMF gate circuit defective.
4. No DTM F tone out-
puts occur. All
other operation
normal.
a. Insert plug into other channel jack; if
a. Channel jack defective.
5. SERVICE REQUEST
light goes out, replace first jack.
b. Logic printed wiring
indicator light
b. Replace logic board A1A2.
does not go out
board A1A2 defective.
when plug is
inserted into one
channel jack.
6. SERVICE REQUEST in-
Acknowledge gate circuit
Replace logic board A1A2.
dicator light does
inoperative.
not go out when
plug is inserted
into either chan-
nel jack.
2-15
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