Crystal Detector; Adjustment Of The Tuning Coils; Fm Tuner Adjustment - Pioneer SX-3900 Service Manual

Crystal Detector
o Set the FM MUTING OFF switch to the OFF
position.
26. Set the FM SG output to 98MHz and 60dB
(unmodulated), and tune the SX-3900 to this
position (fine adjust the tuning knob to ensure
a DC 0V reading between no.S and no.7 ter-
minals of the tuner assembly).
27. Rotate the B core of T201 to obtain a reading
of DC 0V (within r30mV) between terminal
no.9 and ground.
28. Set the FM SG modulation to 40OHz,x7lkHz
deviation.
29. Rotate the A core of T201 to minimize AC
signal level between no.9 and ground.
@ r r
?,)-,
v R 2
L2
@
T o T A P E R E C
t e r m i n a l
F i g . 8 2 A d j u s t m e n t o f t h e t u n i n g c o i l s
s x - 3 9 0 0
D i s t o r t i o n m e t e r
M P X s i g n a l g e n e r a t o r
l@++-A
T 2 t ^ ] l
l_9-D
TC4 TC3 TC2
T u n e r a s s e m b l y
s--8
0--7
A I
f f i t
rh ffi ffi
r- |:I
A C v o l t m e t e r
O s c i l l o s c o p e
F M s i g n a l g e n e r a t o r
T o F M
A N T E N N A
3 0 0 S 2 t e r m i n a l s
F i g . 8 3 F M t u n e r a d j u s t m e n t
I N ( E X T . M O D )