Adjustment - Adcom GTP-506 Service Manual

ADJUSTMENT

Preparation
1. INPUT
- FM mono: 1kHz, 75kHz devi., 60dB/µV
- FM stereo: 1kHz, 67.5kHz devi., 60dB/µV
Pilot signal 19kHz 7.5kHz devi.
- AM: 400Hz, 30%mod.
1. FM ADJUSTMENT
Connection
Item Step
of instrument
1
2
FM
Fig.1
IF/RF
3
Stereo
Fig.2
Distortion
Stereo
Fig.2
Separation
Muting
Fig.1
Level
Pilot
Fig.2
Suppression
Signal
Strength Fig.1
Indicator
2. AM ADJUSTMENT
120V model
Tuning
AM SG
Step
frequency
output
530kHz
1 –
600kHz
400Hz 30% mod. 600kHz
2
60dB/m
600kHz
3 990kHz
400Hz 30% mod.
60dB/m
230V model and worldwide models
AM SG Tuning
Step
output frequency
522kHz
1 – or
531kHz
600kHz
400Hz 30% mod.
603kHz
2
60dB/m
600kHz
3 400Hz 30% mod. 999kHz
60dB/m
FM SG Stereo mod-
output ulator output
99.0MHz
–
1kHz 75kHz devi.
65dBf (60dB)
99.0MHz Ext.
Channel L
mod. 65dBf
or R 1kHz
(60dB)
99.0MHz Ext.
Channel L
mod. 65dBf
or R 1kHz
(60dB)
99.0MHz 18dB –
Channel L or
99.0MHz
R pilot on
mod.65dBf
signal
(60dB)
99.0MHz
–
1KHz 75KHz devi
33dBµ
Output
Adjustment
indicator
point
Digital OSC coil
DC on RF
voltmeter block M971
OSC coil
AC
on RF
voltmeter
block M971
AC
L972
voltmeter
Output Adjustment
indicator point
Digital OSC coil
DC on RF
voltmeter block M971
OSC coil
AC
on RF
voltmeter
block M971
AC
L972
voltmeter
2. OUTPUTS
- Connect the non-inductive type resistor of 8 ohms
to all speaker terminals otherwise noted.
Tuning Output Adjustment
frequency indicator point
DC voltmeter L941
IFT on the
AC voltmeter
99.0MHz
front end
Distortion
L942
analyzer
Distortion IFE on the
99.0MHz
analyzer front end
99.0MHz
Oscilloscope R956
99.0MHz Oscilloscope R941
L903 FOR L
99.0MHz VTVM
L904 FOR R
VFD Signal
99.0MHz
R951
Bars
Adjust
Reference Specification
for
FM tuned voltage: 87.5MHz–108.00MHz
AM tuned voltage: 530KHz–1710KHz
1.35±0.2V
Maximum
Maximum
Adjust
Reference Specification
for
FM tuned voltage: 87.5MHz–108.00MHz
1.3±0.2V (522kHz)
AM tuned voltage: 522KHz–1611KHz
1.35±0.2V (531kHz)
Maximum
AM tuned voltage: 531KHz–1602KHz
Maximum
2
GTP-506
Adjust
Remarks
for
0±100mV FM MUTE/MODE
switch: ON/AUTO
Maximum
Repeat the steps
1 to 3 until no fur-
ther adjustment is
Minimum
necessary.
FM MUTE/MODE
switch: ON/AUTO
Minimum
Don't turn more
than +/-180˚
Repeat stereo
distortion and
stereo separation
Maximum
alignment until
THD at minimum
and separation at
maximum.
Signal
Adjust such that
output
output just unmute
Minimum
8 bars just
lit
More than 1.2v–Less than 10v
1.3±0.2–Less than 9.0v
More than 1.2v–Less than 10v
1.3±0.2–Less than 9.0v
(230V model)
1.3±0.2–Less than 9.0v
(Worldwide model)