Scott 530T 530TL 570T 570TL Service Manual

Page 2

Equipment Required

Audio signal generator,

Disrortion analyzer.

DC voltmeter.

Oscilloscope.

Digital frequency counter, 07100 kHz.
FM multiplex signal generator.

FM RF Tracking

1) Apply 90 Mllz, 1 kHz and 100% modulated, 65 dBf signal
with 76 kHz deviation to the FM antenna terminal.

2) Tune the unit to 90 MHz.

3) Observe the oscilloscope connected to the output terminal
for symmetrical sine wave. It failed, adjust T4.

4) Adjust T1, T2, and T3 for maximum level meter reading
(connected in parallel with the oscilloscope).

5) Readjust the signal generator for 106 MHz, and retune unit,

6) Repeat step 3), if failed, adjust CTg for 570T|Ll , or CTf
for SSOTIL] .

7) Adjust CTa. CTc. and C'le for 570'IILI, and C'Ia, CTc,
and C'Id for 530T] l.l.

FM IF Amplifier

1) Mute the FM local oscillator by shorting CV4.

2) Apply 10.7 Mllz signal from the sweep generator to T3.
See Set-up figure.

3) Adjust T5 and T6 (570TL[L] only) for correct figure as
provided below. It may be necessary to increase or de-
crease the sweep generator output for adjustment con»
venience.

Correc t Incorrect

as too low

lncorrec r
as too narrow

Tuning Meter

1) Remove signal generator output from the unit.

2) Adjust T7 for exact center reading on the FM Center
Tuning meter.

FM IF Distortion

1) Apply 98 MHZ. 1 kHz and 100% modulated. 65 dBf signal
to the unit.

2) Adjust T8 for minimum distortion on the distortion ana-
lyzer connected to the Speaker output terminal.

Signal Strength Meter [FM]

1) Apply 98 MHz, 90 dB signal to the unit.

2) Tune the unit for 98 MHz.

3) Adjust RV] (or RV7 in the 530T/TL) for 90% reading on
the signal strength meterl

Mute Circuit

1) Apply 98 Mllz, 20 dBf signal [0 the unit.

2) Tune the unit (with the Mute switch in the Off position).

3) Set the Mute switch to the On position.

4) Adjust RVS for S70T[Ll, and RVé for 530T[L] so that
the signal is muted.

Pilot Signal (76 kHz)

1) Apply 98 MHz, 65 dBf signal to the unit with no modula-
tion.

2) Adjust RVS for 76 kHz reading on the frequency counter
connected between TP and chassis ground. The deviation
of £200 Hz is acceptable.

Stereo Separation

1) Apply 98 MHz, 65 dBf left channel signal to the unit modue
lated with 1 kHz, 9% pilot signal with 6.75 kHz deviation.

2) Connect a DC voltmeter to the right channel speaker
output terminal.

3) Adjust RV4 for minimum leakage (minimum level) on the
voltmeter.

4) Apply 98 Mllz, 65 dBf right channel signal to the unit
modulated same as tep 1).

5) Move DC voltmeter to the left channel speaker output
terminal.

6) Adjust RV4 again for minimum level.

AM IF Amplifier

1) Apply 455 kllz sweep generator output to the unit AM
antenna terminal.

2) Connect scope to the pin number 12 of IC3 for 570T[Ll
and pin number 12 of lCZ for 530T[L].

'3) Adjust TI} to obtain maximum and symmetrical display as
shown below.

AM Tracking

1) Apply 600 kHz, 30% modulated with 1 kHz to the AM bar
antenna. See test setup figure (Distance between the AM
bar antenna and emitting loop antenna should be 2 foot).

2) Adjust signal generator output so that a sine wave appears
on the scope.

3) Adjust T14 for maxrmum audio output on the DC volt-
meter connected parallel with the scope. When turning
core. the audio level might rapidly increase and the volt-
meter goes off scale. In this case, always decrease the signal
generator output for proper level. Do not change voltmeter
ranger Moreover. always keep the generator output as low
as possible to avoid AGC action (this will prevent inacV
curate adjustments).

4) Adjust the AM loopstick antenna core for maximum output
reading on the voltmeter.

5) Shift generator frequency to 1,400 kHz with same modula
tion condition.