M 7-C / M 17-C / M 27-C
Abgleichvorschriften / Adjustment Procedures
GRUNDIG Service
2 - 3
G B
Adjustment Procedures
1. Tuner
Measuring instruments:
Standard/sweep signal generator, Frequency counter, Oscilloscope, DC voltmeter, AF voltmeter
Service works after replacing the front end: Alignment no. 6
The front end is a completely adjusted module. Only the IF filter is to be tuned to the IF amplifier.
1
1
2
8
4
1
6
1
1124
5115
5103
1102
5102
1103
1110
5123
5122
9116
2106
9101
5111
5114
5112
3142
3158
2140
1121
A
C
7
3
1
2
F1
4
6
B
Alignment
Preparation
Procedure
1. AM IF
2. MW oscillator
3. MW aerial
bandpass circuit
(MW RF)
4. LW oscillator
5. LW aerial
bandpass circuit
(LW RF)
6. FM IF
7. Stereo decoder
MW, Sweep generator 450kHz (R
out
= 50
Ω
) via 100nF to
testpoint
C
U
out
<,
∆
f = 10kHz
Oscilloscope to testpoint
7
DC voltmeter between testpoints
1
and
2
MW
DC Voltmeter to testpoint
6
MW
Feed in a standard signal to testpoint
B
U
out
<, m = 30%, f
mod
= 1kHz
AF Voltmeter to testpoint
7
LW
DC Voltmeter to testpoint
6
LW
Feed in a standard signal to testpoint
B
U
out
<, m = 30%, f
mod
= 1kHz
AF Voltmeter to testpoint
7
FM, 98MHz
Sweep generator 98MHz to testpoint
A
Level abt. 100
µ
V/40dB
µ
V/75
Ω
,
Oscilloscope to testpoint
4
FM
Feed in a signal to testpoint
A
no modulation, Level abt. 1mV/60dB
µ
V/75
Ω
,
Frequency counter to testpoint
3
With 5111 and 5112 set alternating to maximum and
symmetry
With 5114 set to 0V
±
2mV
With 5123 set to 8.3V
±
0.2V at 1602kHz
Check at 531kHz for 1.0V
±
0.4V
With 5102 set to Maximum at 558kHz
With 2106 set to Maximum at 1494kHz
Repeat this adjustment
With 5122 set to 8.3V
±
0.2V at 279kHz
Check at 153kHz for 0.7…1.5V
With 5103 set to Maximum at 198kHz
With F1 set to Maximum and Symmetry
With 3124 set to 152kHz
±
1kHz
IF (MHz)
IF Filter
IF Filter
Ident letter
Colour
10.6500
D
black
10.6750
B
blue
10.7000
A
red
10.7250
C
orange
10.7500
E
white
When replacing one of the ceramic
resonators, take care that the colour codes
of all resonators are the same.