Grundig UMS 2 - Page 28

Abgleich / Alignment UMS 1 / UMS 2
2 - 6 GRUNDIG Service
Alignment
1. Tuner
Test Equipment:
Sweep generator, Test generator, Stereo coder, AF generator, Oscilloscope, Digital voltmeter, AF voltmeter, Distortion meter
Note:
The frontend is a completely preadjusted module. Only the IF filter must be adjusted to the IF amplifier (1). The values of the tuning voltages are:
87.5MHz = typ. 1.6V min 1.3V
108MHz = typ. 8.0V max 9V
ķ
Adjustment Preparations Adjustment Procedure
1. IF Filter
2. Demodulator
3. Station search
4. Stereo Crosstalk
5. Adjacent channel
filter
6. 38 kHz Filter
7. 19 kHz Filter
8. MW Oscillator
9. MW RF Circuits
FM, 98MHz.
Sweep generator 98MHz to aerial socket. Level approx.
100µV / 75Ω.
Oscilloscope to testpoint
B
.
FM, 98MHz
Test generator 98MHz to aerial socket. Level approx.
100µV / 75Ω, ∆f = ± 40kHz.
Distortion meter to AF output .
FM, 98MHz.
Test generator 98MHz, V
RF
= 100µV / 75Ω to aerial socket.
Digitalvoltmeter to testpoint
G
.
FM
Stereocoder, left channel modulated, to aerial socket.
AF voltmeter to AF output, right channel .
FM
AF generator 114kHz, approx. 100mV to the input of F2 D
(Pin 2).
AF voltmeter to the output of F2
DD
DD
D (Pin 4).
FM
Test generator to aerial socket; FM, f
mod
= 38kHz.
AF voltmeter to AF output .
Test generator to aerial socket; FM, f
mod
= 19kHz.
AF voltmeter to AF output .
MW, 531kHz
Digitalvoltmeter to testpoint
E
.
MW, 1449kHz / 558kHz
Test generator via 120 -150µH parallel to frame aerial; AM,
V
RF
= 3µV, m = 30%, f
mod
= 1kHz.
AF voltmeter to AF output .
Adjust F1 a to maximum and symmetry.
Adjust F7 i to K
min
(typ. 0.12%, max. 0.2%).
Adjust R123 S to 1.2V + 0.05V.
Adjust R69 C to minimum.
Control the left AF output with modulated right channel.
Adjust F2 D to minimum.
Adjust F9 J (left channel) and F11 K (right channel) to
minimum.
Adjust F9 G (left channel) and F11 H (right channel) to
minimum.
Adjust L18
VI
to 1.1V.
Adjust C3
IV
and IF filter F6
VII
at 1449kHz and L1
III
at 558kHz to maximum. Repeat the adjustment
reciprocally C3 and L1, end with 1449kHz.
LR
R
LR
LR
LR