Pioneer SX-3700 Service Manual page 17

Y
8 . A D J U S T M E NT S
8 . 1 F M T U N E R
.
Connect the FM SG (FM signal generator) to
the FM antenna 300O terminal.
.
Set the FUNCTION switch to FM. Set the FM
MUTING switch to MONO.
o
The tuning coils in the FM front end does not
have an adjusting core. Consequently, track-
ing adjustments at 90MHz are performed by
regulating the gap between rotor and stator
of the tuning capacitors (VC-1, VC-2, and
VC-3).
The expression "adjust VC (VC-1,
VC-2, and VC-3) found in the text means
that the two outer rotor blades of each of
these tuning capacitors are to be extended
outwards with spatula (Part No. GGK-066)
as shown in Fig. 8-1.
S t a t o r
1. Set the SX-3700's dial pointer to 106MHz,
and the FM SG output to 106MHz, 106dB
(modulation -40OHz, t7 SkHz deviation).
2. Adjust the TC3 to obtain a maximum output
level (REC terminal).
3. Then tune the dial pointer to 90MHz, and set
the FM SG output frequency to 90MHz.
4. Adjust the VC-3 to obtain a maximum out-
put level (REC terminal).
5. Repeat steps 1to 4 above.
6. Reset the FM SG output level to 20 - 30d8,
and adjust TC7, TC2, and TB at 106MHz, and
VC-1 and YC-Z at 90MHz in the same man-
ner as described above in steps 1 to 5.
These adjustments will ensure optimum sensi
tivity in the 90MHz to 106MHz range, and
minimum difference in sensitivity between the
two extreme frequencies.
7. Set the FM SG output to 98MHz, 66dB, and
tune the SX-3700 to this frequency.
8. Adjust the core of T2 to reduce distorition in
the output (REC terminal) to a minimum.
9. Adjust the VR3 so that the 5-point SIGNAL
indicator reads 5 at 55dB of FM SG output.
To REC terminal
B o t o r b l a d e
S p a t u l a
{ G G K 0 6 6 )
Stator -
R o t o r b l a d e
ql+
4fllnx
X
ffi
X
Fig.8-l Adjustment of tuning capacitor
F
J b
JI
p t n
VC
I N ( E X T . M O D )
tr^
Fiq. 8-2 Adiustment point