TANDBERG 3400X User manual

TANDBERG :
3400X 3900X 3600 XD
SERVICE MANUAL
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CONTENTS
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ils INTRODUCTION
1.1 GENERAL
Only LH (Low Noise/High Output) tape should be
used for recording. Make sure that the heads and
tape path are clean.
4
To check the heads:
1. Remove the front head cover by depressing the
spring loaded buttons at both ends and lifting
the cover straight upwards.
2. Remove the back cover by depressing the spring
on its rear side and lifting straight upwards.
When electrical adjustments are to be made, the
bottom panel must be removed.
The tape path must be degaussed both before and
after adjustment. Do not switch off the degausser
until it is about 3 feet from the tape path.
To make magnetized parts of the tape visible, dip
the tape in “Magna See’’. This is a mixture of iron
oxide powder and alcohol. Iron oxide powder can
be obtained from our service department.
NOTE! All paragraphs in this manual are valid for:
Model 3400X, from serial No. 4300 000
Model 3500X, all decks
Model 3600XD, from serial No. 4200 000
1.2 REMOVING THE TOP PANEL
Remove the head covers and the speed selector
knob. Then remove the screws as shown in Figure
1.1. Removal of the top panel will usually only be
necessary for checking and adjustment of clutches
and other parts in the drive mechanism.
Fig. 1.1. Top panel screws

2. MAINTENANCE
Fig. 2.1 Cleaning the tape path
2.1 CLEANING THE TAPE PATH
It is important that the tape path is clean before
adjustments are made. If the heads and guide posts
have been adjusted, the tape path must be de-
magnetized.
Cleaning should be carried out with cotton-bud
sticks (Q-tips) moistened with pure alcohol or
methylated spirit. A special cleaning kit called
“Tandberg Professional Tape Head Cleaner’”’ is
also available.
Aerosol sprays indented for video tape recorders
may be used, but it is not sufficient just to spray
the parts; cotton-bud sticks must also be used.
Obstinate deposits on guide posts should be first
well softened with the cleaning agent and then
removed with the aid of a toothpick.
The pinch roller A should be cleaned if the tape
runs unevenly or if there are visible deposits on
the roller (4 to 6 times a year should be sufficient,
even if the tape recorder is much used). Make sure
that the pinch roller is dry after cleaning.
2.2 LUBRICATION
NOTE! Do not use more than one drop of oil on
each bearing, as excessive oil may penetrate into
the drive mechanism and disturb friction conditions.
The turntables, flywheel and transfer wheel are
mounted in self-lubricating bearings and should not
need attention under normal conditions. If for
some reason lubrication appears to be necessary,
use Teresso oil No 43 or 47 from Esso.
The motor should be lubricated after every
3000 hours of operation. Apply only one drop of
Teresso oil No. 43 or 47 from Esso.

3. MECHANICAL CHECKS AND
ADJUSTMENTS
3.1 CHECKING THE TAKE-UP FORCE AND 3.2 ADJUSTING THE TAKE-UP FORCE
WINDING FORCE
Fig. 3.1 Checking the winding force. Fig. 3.3 Adjusting the take-up force.
A 7” reel with a hole drilled in it 80 mm from the NOTE! Do not touche the textile side of the
hub hole is required together with a torque gauge. belt with your fingers.
Insert the leg of the torque gauge into the drilled
hole. The reel should be allowed to rotate slowly The rubber drive belt does not move during normal
in the direction of the clutch torque while the forward drive. This is because a textile belt pro-
measurements are performed to obtain the speci- vides the take-up force via a drive wheel mounted
fied values, see table 3.2. behind the take-up turntable.
Adjust the take-up force by moving the spring, see
Figure 3.3.
Playback or
wind force
Turntable | Operating lever
position
If the winding force is not correct it should be
adjusted as explained on the next page.
90—250 g*
Table 3.2 Clutch torque
* It is normal for the winding force to increase
20-30% after the machine has been in continuous
operation for some time.

3.3
ADJUSTING
THE
WINDING
FORCE
Adjusting
the
reel
turntables.
The
winding
force
is
determined
by
the
springs
A.
See
Figures
3.5
and
3.7,
If
the
tension
and
the
springs
do
not
change,
the
winding
force
is
deter-
mined
by
the
play
on
the
reel
turntable
and
the
clutch
leaver.
If
the
tension
is
still
not
correct
after
adjusting
the
play,
replace
the
spring
A.
With
the
joystick
in
the
FREE
position,
the
play
on
the
turntable
should
be
between
0.5
and
1
mm
as
shown
in
Figure
3.4.
The
play
on
the
left
turn-
table
can
be
adjusted
by
turning
the
nut
on
the
turntable
spindle.
The
play
on
the
right
twmtable
can
be
adjusted
by
turning
the
turntable
pulley.
NOTE!
If
the
turntable
pulley
(right
turntable)
must
be
unscrewed
from
the
turntable
it
should
be
glued
into
position
after
the
play
has
been
adjusted.
Fig, 3.3
The supply turntable

Fig. 3.6 Checking the play on the clutch levers
Adjusting the clutch lever.
With the joystick in the NEUTRAL (middle)
position, the play on the clutch levers, right and
left, should be between 0.5 and 1 mm.
To adjust this play, turn the screws B shown in
Figure 3.6.
When the play on the turntable and the clutch
levers has been adjusted, the winding forces will
be correct. Check these forces with the aid of the
table on page 5. Adjusting the brakes — see next
page.
Fig. 3.7 The take-up turntable

3.4 ADJUSTING THE BRAKES
This adjustment procedure is the same for both
turntables, but referende is made to the right turn-
table. See Figure 3.8.
Set the joystick to the ® position. Check that the
clearance between the brake pad and the turntable
is 1 mm (0.4”’) approx. If necessary adjust screw D.
Set the joystick to #4, alternatively >» and
check the clearance.
3.5 RUBBER DRIVE BELT
The rubber drive belt does not move in PLAY
mode. This is because a textile belt provides
the take-up force via a drive wheel mounted
behind the take-up turntable.
When changing the drive belt, make sure that the
new belt sits correctly on the motor pulley as
shown in Figure 3.9. The belt must sit in the top
two belt grooves and not in the same groove.
Thebelt must not cross on the wrong side of the
pulley.
Fig.3.8. Adjusting the brakes on the right turntable
Fig. 3.9 Replacing the drive belt

imm
The lifting arms for the drive belt should be
adjusted when the joystick is in NEUTRAL (mid-
position). Adjust for 1 mm clearance with flat
pliers as shown in Figure 3.10. Adjust A first and
the B.
Fig.3.10. Adjusting the clearance on the drive belt
3.6 PRESSURE PAD ARM
With the joystick in the > position, the tension
from the pressure pad arm against the bracket
should be between 80 and 100 g. This pressure
should be measured as shown in Figure 3.11.
Adjust by bending spring A which presses the
pressure pad arm against the head. Check that the
pressure pad arm is parallel when it meets the
bracket. ,
Fig.3.11. Measuring the pressure-pressure

4. TAPE PATH
4.1 CAPSTAN
Before the heads and tape guide posts are adjusted,
the position of the capstan must be checked.
Use special tool No. 5 as shown in Figure 4.1. All
three legs of the special tool should rest on the
upper mounting plate. If one or more of the legs
does not rest on the plate, the capstan needs
adjusting. To adjust the capstan, loosen the three
coloured screws and adjust the capstan until all
three legs of the tool rest on the plate. Tighten up
the screws and check again that the legs are all
touching the plate.
NOTE! The capstan will not go out of adjustment
with normal use and transit.
4.2 HEAD PARALLELISM
Check that the heads are parallel with the aid of a
tape path gauge, see Figure 4.2. This adjustment
affects the passage of the tape through the tape
path, and where the heads are seriously out of
alignment the complete tape path must be checked,
see next page.
iC il __Il
Adjust Adjust Correct
Forwards Backwards Zenith
Fig. 4.1. Adjusting the capstan with special tool No. 5.
Fig. 4.2. Adjusting with the tape path gauge.

4.3 TAPE GUIDE POSTS AND GUIDE
SCREWS
Fig. 4.3. Adjustable tape guide posts.
Thread a tape into the tape path. Pull the joustick
slowly down into the > position and tighten the
tape by rotating the left reel slowly clockwise.
Check that the tape does not come into contact
with the edges of the tape guide screws. If necessary,
adjust the guide screws shown in Figure 4.3.
When the machine is in the playback mode and
tape is passing the heads, the tape may touch the
top edges of the guide posts and guide screws, but
under no circumstances should it twist or distort.
4.4 PINCH ROLLER
The two adjustments possible on the pinch roller
are parallelism and azimuth.
Parallelism.
Push the pressure roller arm in and check that the
pinch roller is parallel with the capstan. To adjust,
loosen screw A and adjust screw B (Figure 4.4)
until the pinch roller and capstan are parallel.
Tighten up screw A.
Azimuth.
Put a tape into the tape path and move the joystick
to » . Check that the tape does not distort when
it has passed the pinch roller. To adjust, loosen
screw A and move bracket C (Figure 4.4) until the
tape runs properly. Tighten up screw A.

4.5 FLUTTER ROLLER
Parallelism.
Loosen screw A (Figure 4.5). Insert a screwdriver
into the slot and move the upper bearing forwards
or backwards until the flutter roller is parallel with
the head front.
Fig. 4.5. Adjusting the parallelisem of the flutter roller.
Azimuth.
Set the speed selector to 7% ips, put a tape into
.the tape path, and move the joystick to > . Insert
a screwdriver as shown in Figure 4.6 and twist it
to move the flutter roller to the left until the tape
just touches the top edge of the nearest tape guide
post:
Fig. 4.6. Adjusting the azimuth of the flutter roller.
Move the screwdriver to the position shown in
Figure 4.7 and move the flutter roller carefully
to the right. If the roller is correctly adjusted the
tape will lift slowly upwards from the bottom part
of the tape guide post and touch the upper part
of the tape guide post without curling.
This adjustment can be checked with a lamp placed
behind the tape path. Look from the front to see
light between the tape and the lower part of the
tape guide post.
Fig. 4.7. Adjusting the azimuth of the flutter roller.

5. HEAD ALIGNMENT WITH
TANDBERG TEST TAPES,
FOUR TRACK
NOTE!
The tape path must be thoroughly cleaned before
adjustments are carried out. Use tape without any
defects. If the heads have grooves caused by wear,
adjustment of the heads should be avoided.
Seal all screws in the tape path after the adjust-
ments have been made.
After replacement of a single part in the tape path,
it may often be necessary to adjust the new part
only. If, however, more parts have to be adjusted,
a complete check and adjustment of the entire tape
path must be performed. Adjustments must be
carried out in the same sequence as explained in
this section.
5.1 PLAYBACK HEAD
Connect an a.c. voltmeter to each of the LINE
OUT sockets and set the SOURCE/TAPE buttons
to TAPE.
Height adjustments
Play back test tape No. 1. This is a full track pre-
recorded tape with 1,000 Hz recorded at 7% ips
and with the area corresponding to track 3 reduced
by approximately 35 dB. Adjust the height of the
playback head by means of screw A, Figure 10.1,
page 21 until minimum output is obtained from
track 3, channel R while maintaining the head-front
parallel to the tape.
Azimuth adjustments
Play back Tandberg test tape No. 2 at 7% ips (or
a standard azimuth tape). Adjust the azimuth posi-
tion of the playback head by means of screw B,
Figure 10.1 (page 21) until maximum output on
the voltmeters is obtained on both channels, or
adjust for the best compromise.
5.2 RECORD HEAD
Height adjustment by visual inspection
Insert a new tape and set the deck to normal
forward drive ( » ). Check visually that the tape
appears to run parallel with the upper track on
the record head, within approximately 0.1 mm
(0.04’’) see Figure 5.1. If necessary adjust the
height with screws C, Figure 10.1, while main-
taining the head-front parallel with the tape.
Height Lateral Alignment
Azimuth Zenith
5.3 HEIGHT ADJUSTMENT BY TRACK
MEASUREMENT
Record in stereo a 1,000 Hz signal well above the
normal level, first in one direction, then in the
opposite direction. Cut off a length of tape and
dip into a solution of fine-grained iron-oxide
powder and alcohol (Magna See). The tracks will
then be visible as four dark stripes. Figure 10.2
(page 21) shows the correct pattern on the tape
and the patterns obtained when the head is either
too high or too low. If necessary, adjust the
height of the head and repeat the measurement
until the patters are correct.
Azimuth adjustment
Load the deck with a new tape and record at
3% ips a 12 to 13 kHz signal in stereo. Set the
SOURCE/TAPE buttons to TAPE. Adjust both
INPUT LEVEL potentiometers for approximately
150 mV reading on a.c. voltmeters connected to
the LINE OUT sockets. Adjust the screw D
(figure 10.1) for maximum output from both
channels, or the best compromise.
Approx. 0.1 mm of upper
pole piece visible above
tape.
Fig. 5.1. Four track record head.

5.4 BIAS HEAD
Vertical adjustment
Move the operating lever slowly to the normal for-
ward drive position ( » ) and check that the head-
front of bias and record heads are parallel. If
necessary, bend the arm of the bias head as required.
Height adjustment
Set the deck to the stereo record mode, and un-
screw the locking screw H (Figure 10.1) about one
turn.
Connect an a.c. voltmeter across each half of the
record head. Move the bias head up or down by
means of adjustment screw M (Figure 10.1) for
the highest possible reading on the voltmeter.
Check that the tape runs freely in the groove in
front of the bias head, and that there is sufficient
clearance between the bias head and the mounting
plate for the record head. If necessary, raise the
bias head slightly. The height position of the bias
head is not critical. Before tightening screw H,
carry out the horizontal adjustment as follows.
Horizontal adjustment
Connect an a.c. voltmeter across each half of the
record head and set the deck to the stereo record
mode. Insert a screwdriver in the groove shown in
Figure 5.2 and tilt the bias head to the right. Then
tilt the bias head carefully by means of the screw-
driver towards the left until the induced voltage
(bias) in the record head increases to a maximum.
Continue tilting the head towards the left until
the induced voltage (bias) in the record head is
reduced to between 10 and 15% below maximum.
Tighten screw H while maintaining the correct
horizontal position for the head. Then re-check the’
output voltage. If the voltage has changed notice-
able, the horizontal adjustment procedure must
be repeated.
Fig. 5.2. Horizontal adjustment for the bias head.
5.5 ERASE HEAD |
Height adjustment
By visual inspection, check that approximately
0.25 mm (0.01’’) of the upper half of the erase
head is visible above the tape, see Figure 5.3. Insert
Tandberg test tape No. 9 and record on channel R
a 400 Hz signal well above normal recording level.
Dip the tape in a solution of fine-grained iron-oxide
powder and alcohol (Magna See). Check that the
recorded track is positioned in the centre of the
erased track, see Figure 10.3, page 21.
Approx. 0.25 mm of
upper ferrite core visible
above tape.
Fig. 5.3. Four track erase head.

6. HEAD ALIGNMENT WITHOUT
TANDBERG TEST TAPES,
FOUR TRACK
6.1 PLAYBACK HEAD
Height adjustment
Adjust the height of the playback head by means of
the screws A, Figure 10.1, page 21. The upper edge
of the tape shall run flush with the upper part of
the head lamination for channel L. See Figure 6.1.
Azimuth adjustment
Set the SOURCE/TAPE buttons to TAPE. Play
back a standard azimuth alignment tape with an
a.c. voltmeter connected to each LINE OUT socket.
Adjust the position of the playback head by the
azimuth adjustment screw B, Figure 10.1 until a
maximum reading is obtained on the voltmeters.
6.2 RECORD HEAD
Follow the instructions given in Paragraph 5.3.
6.3. BIASHEAD
Follow the instructions given in Paragraph 5.4.
6.4 ERASE HEAD
Height adjustments
Adjust the height of the erase head by means of
the screws K and L, see Figure 10.1.
Approximately 0.25 mm (0,01”’) of the ferrite
core for the upper track of the erase head should
be visible above the tape, see Figure 6.2.
Upper edge of tape
coincides with upper
edge of upper pole
piece,
Fig. 6.1, Four track playback head.
6.5. ALIGNING THE HUM SHIELD FOR THE
PLAYBACK HEAD.
The hum shield for the playback head is positioned
on the pinch roller arm so that the shield is right in
front of the head during playback. Set the deck to
stereo playback with both SOURCE/TAPE buttons
in the position TAPE without tape in the tape path.
Put a piece of paper between the photoelectric end-
stopsensor and the light. Set the deck to PLAY.
Connect an a.c. voltmeter to each of the LINE
outputs. Hold the shield and loosen screw E
(Figure 10.1) one quarter turn.
Pull the shield as far away from the head as the
mounting hole permits. Adjust the shield sideways
to obtain a minimum reading on both voltmeters,
or best possible compromise. When adjustment
is completed, tighten the screw and seal with
lacquer.
Approx. 0.25 mm of
upper ferrite core visible
above tape.
Fig. 6.2. Four track erase head.

7. HEAD ALIGNMENT, 2 TRACKS
7.1 PLAYBACK HEAD
Height adjustment
Adjust the height of the playback head by means
of the screws A, Figure 10.1. The tape shall run
parallel with the upper and lower edges of the
laminations of the playback head, see Figure 7.1.
If necessary, re-adjust and check the azimuth
position.
7.2 RECORD HEAD
Height adjustment
Adjust the height of the record head by means of
the screws C, Figure 10.1.
Record on channel L a 1,000 Hz signal at 7% ips
well above normal recording level, first in one
direction, then in the opposite direction. Cut off a
lenth of the recorded tape and dip it into a solu-
tion of fine grained iron-oxide powder and
alcohol (Magna See). Check that the tracks are
distributed symmetrically across the tape. See
Figure 10.4, page 21. If necessary, re-adjust and
check the azimuth position.
7.3 ERASE HEAD
Height adjustment
Adjust the height of the erase head by means of
the screws K and L, Figure 10.1.
Adjust until equal parts of the ferrite cores
are visible above and below the tape, see Figure 7.2.
Upper and fower edge
of tape coincide with
upper and lower pole
pieces.
Fig. 7.1. Two track playback head.
Ferrite cores visible
above and below tape.
Fig. 7.2. Two track erase head.

8. CIRCUITS
8.1 OSCILLATOR
The oscillator frequency is 85.5 kHz for a stereo
recording. Measure this frequency with a frequency
counter on the bias head and adjust with C502 on
the oscillator board.
8.1.1 Erase voltage
Prepare the machine for a stereo recording.
Connect a VVM to the upper half of the erase head
via a low capacity probe. Check that the voltage is
between 80 and 120 V. Check that the same voltage
appears across the bottom half of the head. Set the
machine to record on channel L, and check that
the voltage is the same on the upper half of the
head. The permissable difference between the
voltages on the two halves of the head from a
stereo recording is 10 V max. Carry out the same
check. for channel R.
8.1.2 Bias current, pre-adjustment
Prepare the machine for a stereo recording, and
use a VVM to measure the voltage across the upper
half of the bias head. Adjust the voltage to 22 V
by means of R401. Check that the voltage across
the bottom half of the head is 22 V and adjust
by means of R400.
Demagnetize the heads and tape path.
8.2 PHOTO END-STOP
To change the lamp, take the screw out of the tape
guide post, push the photo end-stop unit back, and
lift it up. See Figure 8.2.
The sensitivity of the photo end-stop can be
adjusted by means of R512 on the oscillator board.
See Figure 8.1.
Fig. 8.1. Oscillator board.
Fig. 8.2. Photo end stop.

8.3 RECORD AND PLAYBACK FREQUENCY
RESPONSES
8.3.1 Record amplifier
Connect a 100 ohm resistor in series with the record
head and earth as shown in Figure 8.3. Connect an
audio oscillator to the LINE input of each channel
and a VVM across the 100 ohm resistor. Short
circuit the trimming capacitor C502 in the tape
recorder oscillator. Put the machine into the stereo
record mode. Set the record level to — 30 dB on
the meter (30 dB below normal). This 30 dB
attenuation should be obtained as follows:
10 dB with the INPUT LEVEL knobs on the
machine and 20 dB with the output control on the
audio oscillator.
Tune the audio oscillator to 400 Hz and use this
for the reference level on the VVM (0 dB).
Sweep the audio oscillator over the frequency
range and check that the readings on the VVM
correspond to the curves shown in Figure 8.4.
8.3.2 Playback amplifier
Connect a 22 ohm resistor in series with the write
lead on the playback head. Connect an audio
oscillator in series with a 1 k ohm resistor and a
100 pF capacitor as shown in Figure 8.5. Connect
a VVM to the outputs of channels L and R, and
set the output selector to STEREO.
Use an VVM to check the shape of the playback
frequency curve. Tune the audio oscillator to 400
Hz and adjust the signal level to 75 mV measured
on the LINE OUT sockets. Check that the fre-
quency responce curves agree with Figure 8.6.
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Fig. 8.4, Recording response curves.
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Fig. 8.6. Playback response curves.

8.4 FAULT IN THE TOTAL RESPONSE CURVE, ONE CHANNEL
f Play back test tape No.3 ‘\,
" to check the playback correction *
, curve, .
%, 1s the playback correction curve correct? #
y, Change over the wiring on .
the tape halves of the playback head.
% Play back No. 3 test tape again.
%, Is the fault on the same channel?
Fault in the playback head.
Fault in the playback correction circuit.
Set the machine to
record. Connect an audio %,
“oscillator to the LINE input and apply *
the frequencies shown in Figure 8.4.
Check that both the meters on
the machine follow the
curve in Figure 8.4
Fault in the record correction circuit
«,
Fault
in
the
record
head
or
the
bias
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9.0 MODIFICATIONS
9.1 CHANGING THE LINE VOLTAGE AND
FREQUENCY
A label on the motor shows you how to wire the
transformer and motor for a different line voltage
and frequency.
When modifying from 50 Hz to 60 Hz, or vice
versa, the motor pulley has to be changed.
Motor pulley for 50 Hz, ordering No. 243940C
Motor pulley for 60 Hz, ordering No. 273787
15V 60 Hz
10. BLOCK DIAGRAMS
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mic MIC/ PRE EOL,
9.2
CHANGING FROM FOUR-TRACK TO
TWO-TRACK VERSION
The following parts must be changed when
a four-track version is modified to a two-track
version and when new heads are fitted.
The value of the total capacitance is labelled on the
heads.
F53-11R F82-07R
C03-10P F83-11P
Record head
Playback head
Erase head D84-11E D87-20E
Bias head 2079-03B 2958-04B
R136 3.9 k ohms 2.7 k ohms
R236 3.9 k ohms 2.7 k ohms
C400 3300 pF* 3300 pF*
C401 3300 pF* 3300 pF*
C402 250 pF* 250 pF*
C403 250 pF* 250 pF*
* Capacitor must be connected in parallel until
value of total capacistance is achieved.
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