Scott 357 B Service Manual

Page 1

II. II. Scatt 357B

ALIGNMENT INSTRUCTIONS

CAUTION: Use isolation transformer or observe polarity when connecting test equipment.

Maintain line voltage at lZOVAC. _ _
Use only enough generator output to obtain a suitable indication.

Allow a 15minute warmeup period.

10.7MHZ

FIG. I

IO.7MHz

FIG. 2

IM ALIGNMENT-SELECTOR IN AM POSITION

Connect generator across loop fashioned of several turns of wire. Set volume at maximum.

GENERATOR RADIO DIAL

FREQUENCY SETTING INDICATOR ADJUST REMARKS

455kI-Iz Tuning gang Output meter T302! Adjust for maximum. Repeat until

women; fully open across voice coil T304 no further improvement is noted.

Modulation

600kHz Tune to signal " T202 Adjust for maximum.

lsAOkHz " " C232 Adjust for maximum.

IOORHz " " 5225 Adjust for maximum. Repeat AM alignment
until no further improvement is noted.

M IF ALIGNMENT USING AM SIGNAL GENERATOR-SELECTOR IN FM POSITION

' gh side of generator thru .OOImfd to junction L205 and C213,

low side to ground.

GENERATOR RADIO DIAL

- FREQUENCY SETTING INDICATOR ADJUST REMARKS

0.7MH2 Point of non- DC probe of WWI T306 (Pri.) Adjust for maximum.

Unmodulated interference to cathode D305, T305,T303,
common to ground. T301,T201

" " DC probe of WW T306 (Sec) Adjust for zero reading. A positive

to Jct R312ER319 or negative reading will be obtained
common to ground. on either side of correct setting.

Page 2

ALIGNMENT INSTRUCTIONS (Continued)

FM IF ALIGNMENT USING FM SIGNAL GENERATOR-SELECTOR IN FM POSITION

High side of generator thru .001mfd to junction L205 and C213,
Use only enough marker signal for indication.
with 450m: sweep. Use 60-hertz sawtooth voltage in scope for horizontal deflection.

low side to ground.

Use 60-h_ertz frequency modulated signal

GENERATOR

RADIO DIAL

scope to junction
R312 5: C319,
side to ground.

FREQUENCY SETTING 'ND'CATOR ADJUST REMARKS
10.7MHz Point of non- Vert input of T306 (Fri), Disconnect stabilizing capacitor C320
ASOkHz Sweep interference scope to cathode T305,T303, Adjust for maximum gain and symmetry
D305, T301,T201 of response similar to Fig. 1 with
side to ground. markers as shown. Reconnect C 320.
" " Vert input of T306 (Sec) Adjust T306(Sec) to place marker at

center of S curve, similar to Fig. 2.
Readjust T306(Pri) for maximum ampli-
tude and straightness of line.

FM RF ALIGNMENT-SELECTOR IN FM POSITION

Connect generator across antenna terminals with lZO-ohm carbon resistor in series with each lead.
Adjustment of coils by bending should not be attempted unless the coil is deformed or replaced.
GENERATOR RADIO DIAL
FREQUENCY SETTING INDICATOR ADJUST REMARKS
88MHz Low freq end DC probe of VTVM L206, Adjust for maximum.
Unmodulated to cathode D305, L201

common to ground.
108 MC Tune to signal " C217,C212, Adjust for maximum. Repeat FM RF steps
Unmodulated c203 until no further improvement is noted.

FM STEREO MULTIPLEX ALIGNMENT USING FM STEREO SIGNAL GENERATOR (t .0001% ACCURACY)

High side of generator thru 47K tojunction R312 and C319 low side to ground.
GENERATOR
FREQUENCY INDICATOR ADJUST REMARKS
67kHz Vert input of scope thru 47K to Adjust for MINIMUM.
Base (1505» low side to ground. L502
lngz Vert input of scope thru 47K to Adjust for maximum.
cathode 9501 low side to ground. L503
leHz Vert input of scope thru 47K to Adjust for maximum 38kHz response.
Jct.D504§D5061W side to ground. T501
Modulated Vert input of scope to point R518, Adjust for MINIMUM. This step
Left Channel pnz low side to ground. K519 should require only slight adjustment.
Modulated Vert input of scope to point Check for MINIMUM. If necessary, make
Right Channel PT6 low side to ground. compromise adjustment of R518,R519.