Tandberg TPT 3001 Service Manual

Page 1

TANDBERG®

Programable FM Tuner 3001
Circuit Diagrams and
Alignment Instructions

TANDBERG®- The European Alternative

Page 2

Contents

Page
Mechanical service .................................................................. 3
Electrical service .................................................................... 6
Main circuit diagram ................................................................. 7
Power supply and dial pointer adjustments ............................................... 8
Oscillator and front end .............................................................. 10
Limiter/Detector below serial No. 00700 ................................................. 12
Limiter/Detector above serial No. 00700 ................................................. 14
Selectivity below serial No. 00700 ...................................................... 16
Selectivity above serial No. 00700 ...................................................... 18
Signal meter, muting level ............................................................ 20
Tuning system 1 .................................................................... 24
Tuning system 2 .................................................................... 26
Stereo decoder ..................................................................... 28
Integrated circuits .................................................................. 32
Other PC boards ............................................... ..................... 34
Modifications ...................................................................... 35
Technical data ..................................................................... 36

Page 15

LIMITE

P7", cum

Figure 24 Limiter/detector board above serial No. 00 700, component side

Limiter/Detector, d.c.-reference and distortion

0 Connect oscilloscope (dc-mode) to the
F M-Multipath Vert. terminal.

0 Pull out signal plug P201 on the selectivity box
(see figure 25).

0 Connect signal generator to JZOl (see figure 25).

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30m
. U . . . . L, L,

Figure 25 Test points

0 Tune the generator to approx. 10.7 MHZ,
500 [IV modulated mono 1 75 kHz dev., 1 kHz
modulation.

0 Set Bandwidth selector to Narrow.

O Fine~tune the generator for symmetrical sinewave
on the oscilloscope (figure 26). The frequency
thus found is now used for the further
adjustments.

Figure 26 Symmetrical sinewave

0 Switch off the modulation and set the generator
output to 20 mV.

0 Set Bandwidth selector to Wide.

0 Pull out interconnector board No. 45430 (see
figure 2 7).

0 Connect a d.c. millivoltmeter (range 100 mV) to
P711, pin 4 (strap next to R786 on the main
board, see figure 27).

O Shortcircuit the strap to ground for a second.

L

P711i4l fl
7____
45430 [EU 4%)
if. mill-Ii H
L4 T. U 5

Figure 27 Test points
0 Adjust L308 for slightly less than 5 mV reading
on the millivoltmeter.

. Connect an oscilloscope (a.c.-mode, 5 mV) to
M501 on the decoder board (see figure 25).

0 Adjust L309 for minimum 10.7 MHZ on the
oscilloscope.

0 Put back interconnection board No. 4-5430 (see
figure 27).

0 Set the generator modulation to
i 75 kHz, 20 mV.

0 Connect distortion meter to one of the Fixed
Output terminals.

0 Adjust L307 for minimum distortion, typical
figure 0.006%.

0 Check the other channel.
0 Reduce the signal level to approx. 5 11V.

0 Connect the oscilloscope to one of the Fixed
Output terminals.

0 Adjust L301 for as clean and distortionfree
sinewave as possible. Start from an inner
position and screw the core outwards.

0 Put back the signal plug P201 on the selectivity
box (see figure 25).