Grundig PA 2 Betriebsanleitung Seite 46

Abgleichvorschriften / Adjustment Procedures
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
Adjustment
1. IF Filter FM, 98MHz.
Sweep generator 98MHz to aerial socket. Level approx.
100µV / 75Ω, ∆f = ±200kHz.
Oscilloscope to testpoint B .
2. Demodulator FM, 98MHz
Test generator 98MHz to aerial socket. Level approx.
100µV / 75Ω, ∆f = ±200kHz.
Distortion meter to AF output.
3. Station search FM, 98MHz.
Test generator 98MHz, U
Digitalvoltmeter to testpoint G .
4. Stereo Crosstalk FM
Stereocoder, left channel modulated, to aerial socket.
AF voltmeter to AF output, right channel.
5. Adjacent channel FM
AF generator 114kHz, approx. 100mV to the input of F2 D
filter
(Pin 2).
AF voltmeter to the output of F2 D
6. 38 kHz Filter FM
Test generator to aerial socket; FM, f
AF voltmeter to AF output.
7. 19 kHz Filter Test generator to aerial socket; FM, f
AF voltmeter to AF output.
8. MW Oscillator MW, 531kHz
Digitalvoltmeter to testpoint E .
9. MW RF Circuits MW
Test generator via 120-150µH parallel to frame aerial; AM,
U = 3µV, m = 30%, f
RF
AF voltmeter to AF output.
Amplifier
Test Equipment:
Digital voltmeter
Adjustment
1. Quiescent Current No Input Signal. Volume to Minimum. Switch on the set for
at least 2 minutes.
Left channel:
Digitalvoltmeter between testpoints Al and Bl.
Right channel:
Digitalvoltmeter between testpoints Ar and Br.
2 - 7
Preparation
= 100µV / 75Ω to aerial socket.
RF
D D
D (Pin 4). D
= 38kHz.
mod
= 19kHz.
mod
= 1kHz.
mod
Preparation
Adjustment Procedure
Adjust F1 a to maximum and symmetry.
Adjust F7 i to minimal Distortion (typ. 0.12%, max.
0.2%).
Adjust R 123 S to 1.2V + 0.05V.
Adjust R 69 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 to 1.1V.
VI
Adjust C3 and F6 at 1449kHz and L1
IV VII
558kHz to maximum. Repeat the adjustment reciprocally,
end with 1449kHz.
Adjustment Procedure
Left channel:
±
Adjust with R516 for 3mV 0.5mV.
Right channel:
±
Adjust with R522 for 3mV 0.5mV.
PA 2 / PA 3
at
III
GRUNDIG Service