Dynatuner FM-1 Istruzioni per il montaggio Operazione di allineamento - Pagina 13
Sfoglia online o scarica il pdf Istruzioni per il montaggio Operazione di allineamento per Sintonizzatore Dynatuner FM-1. Dynatuner FM-1 20.
Stampa la paginaThere are two small brass-plated self-tapping
screws which will be used to secure the brass front
plate to the front panel. To avoid scratching the
brass plate, it is wise at this point to cut their threads
in the holes above and below the tuning capacitor
shaft by inserting these screws and removing them.
This will enable much easier insertion when the
front plate is installed.
Peel off the protective plastic film on the face of
the brass front plate. Remove the
%"
nut holding
the volume control to the front panel. Insert the
rectangular plastic insert into the front plate cutout
from the rear (the top edge is narrower than the
bottom). Place the front plate against the steel front
panel so that the plastic insert is held between the
two plates, and the volume control shaft and the
tuning capacitor shaft protrude through both panels.
Install the
%/1
nut on the volume control shaft and
tighten it. Secure the front plate to the panel with
the two brass self-tapping screws above and below
the tuning shaft. Rotate the volume control shaft
fully counter-clockwise and install the small knob
with the pointer at the? o'clock position. The knob
is pushed onto the knurled shaft. Fasten the large
knob onto the tuning capacitor shaft by tightening
the set screw.
ALIGNING YOUR DYNATUNER
The Dynatuner is unique in its simplicity of alignment.
It can be aligned using the tuning eye as an indicating
instrument, and this alignment is as precise as can be
accomplished with the most complex laboratory equipment.
It is important to emphasize that when this procedure has
been carefully followed, it is not possible to "improve" on
this alignment, and the Dynatuner will meet the most
rigorous performance standards. It is essential that any
serviceman who works on this tuner be informed of this
procedure, and that he is also advised that conventional
"sweep" alignment techniques are not considered either
satisfactory or desirable.
Certain parts of the Dynatuner have been preset close to
the proper alignment point. All of the LF. transformers,
the discriminator transformer, and the slug-tuned coils on
the RF. board PC-? are preset. Several approximate
adjustments should be made first, which will permit
reception of local stations, and then complete alignment
can b/rried out.
l6/l The osciJlator trimmer capacitor C8 screw (accessible
from below the chassis) should be turned until the
head of the screw is 5/16/1 from the triangular nut.
On the top of tuning capacitor Cl there are two
adjustment screws (trimmer capacitors) accessible
through the two holes in the top of the tuning capaci-
tor shield. The center screw (Cl-D) adjusts the
mixer, and the rear screw (Cl-B) adjusts the RF.
stage. The approximate settings given in steps #2 and
#3 below have already been made as the capacitor is
supplied to you.
2(0
Turn in the screw CloD on the center (mixer)
.I-
section until it is in all the way. It should be snug,
~
but do not force it. Then back it off
),i
turn counter-
clockwise.
30urn in the screw Cl-B on the rear (RF.) section
until it is in fully, but do not force it. Then back it
off
%
turn counter-clockwise.
Now you shou, --make one final inspection of the
unit to see
t all connections are soldered, that
,here are
0
loose wire clippings or pieces of solder,
nd t
there are no parts hanging in the air. Also
ch
to make certain that there are no bridges of
del' across the insulated areas of the circuit boards,
If everything appears to conform to the pictorial
diagrams and photographs, plug the Dynatuner in
( to AC current sources only) and turn it on.
With an antenna attached, and an audio connect-
ing cable between the tuner and an amplifier or
preamplifier as described in the section "Using Your
Dynatuner", you should turn the volume control
knob on the tuner fully counter-clockwise and then
turn on the on-off switch. The dial light should
light, and there should be a slight glow visible in
each tube as its heater lights, and then the tuning
eye should glow. All of this will take only about
15 seconds. When turmng the tuning knob, some
deflection of the tuning eye should be apparent as
the tuning passes through the frequencies of local
stations. By turning the volume control knob clock-
wise, it should be possible to hear some hiss between
stations and sound from the stronger stations. If aU
these effects cannot be obtained, refer to the section
"In Case of Difficulty" before attempting to use
the tuner further or to align it.
As soon as it is evident that there is reception of
some stations, we suggest that you leave the tuner
operating for about an hour to let the tubes age and
for operating conditions tQ stabilize. This will elimi-
nate the need for re-alignment after alignment is
carried out. You should be able to enjoy the use of
the tuner during this time since normally reception
wiJl be quite adequate on local stations.
The alignment tools to be used are: a plastic tool
(supplied) which has a hexagonal end for adjustment
of the tuning slugs in the I.F. and discriminator
transformers, and a small tipped screwdriver with
an insulated handle. Only the plastic tool should be
used to adjust the transformers. Any other type of
instrument win damage the tuning slugs. When
using the plastic alignment t90l, all adjustments are
made using the end which h'as a shoulder to prevent
inserting the tool too far.
BE CAREFUL IN HANDLING THE CHASSIS
DURING ALIGNMENT. THERE
IS SOME
SHOCK HAZARD DUE TO THE EXPOSED
WIRING.
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