TM 11-5826-225-35
Terminals
Ohms
Termlnals
Ohms
Transformer or coil
6.9
L 2 7 -------------- - - - - - - - - - -
26
L1 --------------------------
L28 -------------- - - - - - - - - - -
3.'7
28
1-2
L3 -----------------
L29 ______________ - - - - - - - - - -
2.5
2.1
2-3
L30 -------------- - - - - - - - - - -
1.2
19
L4
-----------------
1-2
L31 -------------- ----------
2.6
2-3
1.4
1
6.4
1-2
I
L5 ________________
2-3
Less than 1
b. Typical System Troubles Caused by Defec-
,,--------
16
L6
---------------
tive Receiver. The following chart lists symp-
Less than 1
L8 ---------------- ---------
1-2
54.5
L11 _______________
toms that indicate improper equipment per-
46
L12 through L15 --------- - - - - - - - - -
formance, The chart also lists a probable cause
62
L16 --------------.,--------
in the receiver for each of these symptoms.
10
L17 --------------- ---------
This chart does not include all probable causes
Less than 1
L18 ______________ - - - - - - - - - -
L22 -------------- ---------
16
in the receiver for a given symptom, or prob-
26
L24 _______________ , - - - - - - - - -
able causes in other components or in the air-
1.8
L 2 5 - - - - - - - - - - - - - - - _________
craft wiring.
L26 --------------- - - - - - - - - - -
Less than 1
Symptom
Item
Probable Cause
Tuning servo has a S1OW response and will not
Capacitor C74 coupled to control winding of tuning
1
servo motor MGl changes value.
reach a null.
2
On the 190- to 400-kc range, radio station fre
control unit.
3
Local oscillator Q6 defective.
Spurious frequencies on all frequency ranges ____
4
BFO inoperative -----------------------------------
Capacitor C99 in bfo circuit defective. RF coil L16 open.
6 Bearing indicator will not reach null in adf mode
Bypass capacitor C82 (selected) on T18-1 defective.
6 Low sensitivity in adf mode __________________
B3 defective.
7 Loop and adf modes inoperative .-.. ___________
Shorted winding in T18. The 110-cps oscillator Q22 or
f lo -cps amplifler Q23 defective. Emitter bias resistor
R122 on Q23 defective by reason of capacitor C67
king shorted.
Intermittent operation in loop and adf modes ---- Bypass capacitor C5 on Tl, T2, and T3, defective.
8
Emitter bypass capacitor C6 on first RF amplifier
Q1 defective.
9 Bearing indicator pointer erratic on tail bearings
Capacitor at junction of emitter bias resistor R31 and
base-bias resistor R30, defective (fourth IF amplifler
Q10).
10 In ADF mode bearing indicator either has a slow
Resolver servo motor B5 has insufficient torque. Second
1
response or is inoperative.
RF amplifier Q3 defective. Q17 bias adjust variable
resistor R131 out of adjustment.
11 Homing function weak and will not reach aural
Filter capacitor C146 in voltage regulator circuit de-
null in loop mode.
fective. Second audio amplifier Q13 defective. Audio
coupling capacitor C83 defective.
12 Inoperative in all mode. ______________________ Emitter bias resistor R107 on second IF amplifier Q8
defective.
13 In loop mode:
I
(a) Resolver servo-amplifier bias resistor R133 (selected) has
(a) Bearing indicator rotates too slow when control unit
too low a value. Capacitor c82 (selected) defective
LOOP switch is in slow slew position.
(b) Resolver, servo-amplifier bias resistor R133 (selected) has
(b) Bearing indicator rotates too fast when control unit
100 high a value.
LOOP switch is in slow slew position, and/or in-
LOOP
dicator rotates too slow when control unit
switch is in fast slew position,
Rf coil L12 Open.
14
RF gain ---;-----------
No manual control of
Audio output q ignal present when control unit
Diode CR1l in voltage regulator circuit oscillating.
16
GAIN control la in full c o u n t e r - c l o c k w i s e
position.
Capacitor C78, connected between terminals 3 and 6 of
16
Little or no audio output ---------------------
T20, defective.
2-33
Change 5
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