Dynatuner FMX-3 Assembly instructions

SERIAL NUMBER
This number must be men-
tioned in all communications
concerning this equipment.
INSTRUCTI
NS FOR
ASSEMBLY
ALIGNMENT
OPERATION
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VOLUME
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Price $1.00
929011
tJlUI\IaCD il\lc_ 3060 Jefferson St., Philadelphia, Pa.19121 U.S.A.

FMX-3 MULTIPLEX INTEGRATOR
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DESCRIPTION
The Dynatuner FMX-3 is a multiplex integrator designed
to convert the FM-l Dynatuner into a compatible FM-
Stereo-Mono tuner. When installed and aligned, the com-
pleted system exhibits specifications which are virtually
unchanged from those of the basic tuner. Separation of the
two stereo channels is 30 db or more over the useable audio
range, closely approaching the limits of the system, and the
Dynatuner FMX-3 is uniquely able to maintain this high
degree of separation even with very low signal strengths.
The FMX-3 has some novel features which contribute to
ease of operation as well as a high level of performance.
The FMX-3 has three basic sections:
1. A 19KC and doubler channel using a 6BL8/
ECF80 tube, in which the pilot signal of the
stereo broadcast is amplified and doubled to
reconstruct the 38KC carrier.
2. A symmetrical gated bridge detector utilizing 4
matched IN541 germanium diodes which detect
the signal.
3. A
twin triode 12AX7jECC83 tube which am-
plifies the signal. This stage is afeedback
stage, providing alow output impedance with
low distortion.
When there is a stereo broadcast, the doubler circuit
produces from the tran.smitted 19KC stereo pilot signal, a
38KC signal which is locked in phase with the pilot signal.
This 38KC signal is amplitude controlled by a limiter to
reject AM noise and to maintain a constant carrier level.
The doubler circuit also provides a signal for actuating the
STEREOCATOR to indicate the existence of a stereo broadcast.
The same STEREOCATOR is used as an alignment indicator
when initially adjusting the integrator.
The reconstituted 38KC carrier is combined with the
detected FM signal in a special balanced transformer. This
signal has been modified by augmenting the portion which
contains stereo information and by introducing a notch
type filter at 67KC in order to eliminate problems from
stations with subsidiary non-stereo multiplex operation.
The combination of the 38KC carrier and detected FM
signal has an envelope on which one side is left channel
and the other side is right channel modulation. Each chan-
nel is detected by half the balanced bridge in which the
arms alternately open and close, actuated synchronously
by the 38KC signal. Balanced detection insures linearity.
The demodulated signals are de-emphasized. They pass
through a dual volume control which handles both chan·
nels, and then are amplified in the output stage where the
unwanted signal portions above the audio spectrum are fil-
tered out. The resultant output contains very small per-
centages of 38KC and its harmonics so that there are no
signals to cause spurious beats with tape recorder bias
frequencies.
There are two very important benefits from this system.
First, its very high degree of linearity provides minimum
distortion. This results in stereo reception of a quality
commensurate with the finest mono broadcasts, plus all the
benefits of excellent stereo separation. Second, there is no
switching required of the user in the transition from mono
to stereo or vice versa. The integrator takes care of tllis
automaticallY since the 38KC carrier does not exist in the
absence of t'he 19KC stereo pilot signal, and there is no
free-running oscillator to cause beats and whistles which
might be encountered under many conditions of lise.
The integrator fits inside the Dynatuner FM-l in the
space provided. It requires slight modifications in the FM-l
because some extra features are included in the integrator
which more than outweigh the short time required for their
inclusion .. These features are the sn~REOCATOR and the dual
volume control, which together greatly simplify stereo
reception.
USING YOUR. MULTIPLEX DYNATUNER
Operation of the FMX-3 equipped DYllahmpr is re-
markably simple. The socket marked "A" (indicated on the
bottom plate beneath the output sockets) is the left chan-
nel output. The "B" socket is the right channel output.
Shielded cables should connect these w.ith the stereo pre-
amplifier,
or directly to power amplifiers if no preamplifier
is to be used. Either the FM-AM input..<; or the FM-MPX
inputs on the preamplifier may be used. The outputs of the
Dynatuner can go into any input of 100,000 ohms imped-
ance or greater which can accept signal levels between one
and two volts.
Stereo reception is just as simple as mono reception with
the multiplex Dynatuner. ,Just tune the station. Amono-
phonic broadcast will automatically be heard through both
speakers. A
stereo broadcast will be received with maximum
separation (depending on the program material) without
adjustment. Because the integrator performs the necessary
switching automatically, the preamplifier may usually be
left in
the "stereo" mode. Under certain conditions of mono
reception, however, switching the preamplifier to the A+B
(L+R) mode may' afford reduction of noise components
on weaker signals.
Refer to your Dynatuner manual for further information
on tuner usage. When using the FMX-3, the lower beam of
the tuning eye is used for normal tuning, and the upper
beam illuminates the word "STEREO" when a stereo station
is transmitting. Between stations, the upper beam may light
or flicker. There can be no confusion as to whether you are
listening to a stereo station if you tune for closure of the
lower beam {lrst, and then observe whether "STEREO" is
lighted.
Noise on extremely weak signals (there is some
19KC in random noise) and 19KC harmonics in the pro-
gram material may also cause flickering of the STEREOCATOR
during mono reception.
For those who use the unit with amono system, in
anticipation of the time when they will have the remainder
of the stereo system, it is suggested that they use a "Y"
connection to feed both outputs into asingle channel sys-
tem.
This will avoid limiting reception to one channel only
when a stereo broadcast is received.
It is important to note that a proper antenna is more
important for stereo reception than for mono reception.
Many problems of noise and distortion can be eliminated
by rotating the antenna for best results on individual sta-
tions. The ideal procedure is to use a directional FM
antenna with a rotator and a variable attenuator in the
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feed line. This is not practical for everybody, however, but
orientation of the antenna for best reception is essential
even when using an indoor folded dipole of the type shown
in the Dynatuner FM-l manual. If relocation of an indoor
antenna is frequently required for best results, an indoor
all-band TV antenna of the "rabbit ears" type may prove
more convenient than the twin-lead folded dipole.
READ THESE INSTRUCTIONS FIRST
A. If this FMX-3 kit is to be incorporated into an already
completed FM-l Dynatuner, you may proceed with the
complete assembly instructions.
B. If this FMX-3 has been purchased as a Semi-Kit, with
the etched circuit board factory preassembled, you need
not check that section of the parts list which includes
the items on the PC-12 board. You may proceed with
the assembly instructions, ignoring the section describ-
ing the assembly of the etched circuit board.
C. If you have not yet assembled your FM-l Dynatuner
kit, you can save afew minutes assembly time by
noting the following changes in your FM-l manual:
1( ) page 5, column 2, step 1: Do not install resistors
R20, R30 or R35.
2( ) page 6, column 1, step 4 at top of page: Do not
install capacitor C28.
3( ) page 6, column 2, step 13: Delete this step.
4( ) page 7, column 2, step 31: Delete the sentence,
"Solder all three wires".
5( page 10: Front Panel Assembly: Delete steps #1
through #19 inclusive.
6( ) page 10, column 2, step 21: Delete this step and
replace it with the following instructions: Twist
together a 9" black wire and a 9" green wire.
Thread these wires through the small slot in the
front of the chassis, and through grommet #2.
Connect the black wire to lug #2 of the three lug
terminal strip. Connect the green wire to lug #1 of
the three lug terminal strip. Also at eyelet #37 on
the bottom of PC-8, solder should be flowed onto
the board and over to the chassis to make agood
ground contact to the chassis.
In the Preliminary Assembly and Wiring instructions
for the FMX-3, you can delete steps #1 through #8
inclusive. Now proceed with the assembly of your FM-l
Dynatuner through to the bottom of Page 10 in its
instruction book. The EM-84 tube, the volume control,
and the plastic front plate insert supplied with the FM-l
are not used with the FMX-3. Next assemble the FMX-3.
Install the 12AX7 in the FMX-3 but leave out the
6BL8jECF80 while aligning the FM-l according to its
instruction manual. Then align the FMX-3 as shown
later in this manual, after installing the 6BL8.
D. If you have purchased your FM-l Dynatuner as a
Semi-Kit, and it is not yet assembled, you can save a
few minutes assembly time by noting the following
changes in your FM-l SK manual and supplementary
instructions:
1( page 6, column 2, step 13: Delete this step.
2( page 7, column 2, step 31: Delete the sentence
"Solder all three wires."
3( ) page 10 of Supplementary Instruction sheet for
the Semi-Kit: Front Panel Assembly: Delete
2
steps #1 through #11 inclusive. Add the following
instructions
after step #11: Twist together a9"
black wire and a9" green wire. Thread these wires
through the small slot in the front of the chassis,
and through grommet #2. Connect the black wire
to lug .#2 of the three lug terminal strip. Connect I
the green wire to lug #1 of the three lug terminal "
strip.
In the Preliminary Assembly and Wiring instructions
for the FMX-3, you can delete steps #1 through #6
inclusive. Now proceed with the assembly of your FM-l
SK Dynatuner through to the bottom of the supple-
mentary instruction sheet. The EM-84 tube and the
plastic front plate insert supplied with the FM-l SK are
not used with the FMX-3. Next assemble the FMX-3.
Install the 12AX7 in the FMX-3 but leave out the
6BLBjECF80 while aligning the FM-l according to its
instruction manual. Then align the FMX-3 as shown
later in this manual, after installing the 6BLB.
ASSEMBLY INSTRUCTIONS
There are five basic steps in the incorporation of your
Dynakit FMX-3 Multiplex Integrator into the Dynatuner:
A. The installation of the unique STEREOCATOR tuning
system requires replacement of the present tuning eye
and socket, and afew component changes on the PC-8
board in the tuner.
B. The present volume control is replaced with a dual
volume control which operates on both stereo channels.
C. Assembly of the PC-12 integrator circuit board.
D. Interconnection of the FMX-3 and the FM-l tuner.
E. Alignment of the FMX-3.
Refer to the FM-l instruction manual for detailed I
instructions on proper wiring and soldering technique. A
GOOD SOLDERING JOB IS ESSENTIAL TO THE
PERFORMANCE OF YOUR TUNER. ALL SOLDER-
ING MUST BE DONE WITH ROSIN CORE SOLDER.
Whenever soldering is required, the instructions indicate it
by "( S) ". If this symbol is not shown after aconnection i!)
specified, it indicates that further connections will be made
at that point before soldering.
All resistors in the FMX-3 are 1/
2watt.
The color coding
which specifies their value is indicated as they are used.
The first color is nearest the end of the resistor, and any
fourth color band should be ignored. All capacitors are
marked with their value. Whenever a length of hookup
wire is specified, strip II!" from each end unless otherwise
specified.
BEFORE STARTING WORK ON THE DYNA-
TUNER, MAKE SURE THE LINE CORD IS DIS-
CONNECTED FROM ANY SOCKET.
Preliminary Assembly and Wiring
1( Remove the cover and bottom plate of the tuner.
Save all the hardware.
2( Remove the knobs. Remove the two brass screws and
the nut on the volume control which secure the brass
front plate. Remove the front plate and plastic insert.
3( ) Remove the three sets of #4 hardware which secure •
the front panel to the chassis. Save the hardware.
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4 ( ) Snip off at the socket, all of the wires connected to
the tuning eye socket VB. Snip off all wires con-
nected to the volume control. Set the front panel
aside. Remove the tuning dial disc to prevent break-
age. Remove V6 and V7 for convenience in making
future connections.
5( Remove the tuning eye socket V8 from the front
panel. Save the hardware.
6 ( Remove the volume control from the front panel.
Save the %" lockwasher, and the %" nut which was
removed in step #2.
7( ) Remove the seven wires which are connected to eye-
lets h25, #26, #28, #30, #36, #37 and #38. Heat the
eyelets from below and withdraw the wires from the
top.
8 ( ) Remove the following four parts from the PC-8
board, checking with the pictorial diagram for loca-
tion: R20 (blue-gray-yelJow); R30 (brown-black
orange); R35 (blue-gray-orange); C28 (.0075 disc
capaci tor). These should bc removed by pulling
gently on the component with a pilir of pliers as
each lead is heated from the other side of the board
with a soldering iron. Clear the hole of solder by
sweeping away the solder with the tip of the iron,
after wiping the tip of the iron clean. Do this quickly
with very light pressure to avoid excessively heating
the board. Propping the tuner up with books will
make the removal of these components simpler.
9( ) Mount the tuning eye socket V8M (with mounting
flange), on the front panel with two sets of #4 hard-
ware. Note that it is now installed with the blank
space between pins #1 and #9 at the top of the panel.
1O( ) Place the %" lockwasher on the shaft of the dual
volume control and insert the control into its hole
in the front panel. Locate the lugs as shown in the
pictorial diagram. Fasten loosely with the Ye" nut.
11( ) In the location marked R20 on PC-8, insert a
100,000
ohm (brown-black-yellow) resistor R20M.
Solder both leads and snip oft· the excess close to the
bottom of the board. .
12 ( )
In the location marked R35, insert an 18,000 ohm
(brown-gray-orange) resistor R35M. Solder both
leads and snip off the excess.
13( )
In the location marked C28, install resistor R39M.
This resistor is 22,000 ohms (red-red-orange) .
Squeeze the leads together to fit the present hole
spacing. Soldel' both leads and snip off the excess.
14 ( ) Refer to Detail A, and make the
"piggy-back" combination of the 470
mmfd capacitor C41M and the 22,000
ohm (red-red-orange) resistor R30M.
Solder. This combination is installed
in the location marked R30. Solder
both leads and cut off the excess.
15 ( ) Strip 114" from the ends of the black DETAll"A"
and green twisted pair of wires which
protrude from the small slot in the front of the
chassis. Connect the black wire to pin #4 of the
socket V8M (S). Connect the green wire to pin #5
of socket V8M (S).
16( ) Cut a 3/1 black wire. Strip one end %", and feed it
through pin #3 and connect it to pin hI of socket
V8M. Solder both pins. Position this wire under the
right-angled mounting bracket for V8M and close to
the front panel.
17 ( ) Connect one end of an 81 12" red wire to pin #6 of
socket V8M (S). Feed the other end through the
small slot in the front of the chassis.
18( ) Connect one end of an 8" grf>en wire to pin #7 of
socket V8M (S). Feed the other cnd through the
slot in the chassis.
19( Connect one end of a 3" red wire to pin #8 of socket
V8M (S).
20( Connect one end of a31 12" green wire to pin #9 of
socket V8M (S). Position this wire under the
bracket and close to the front panel.
21 ( ) Connect one end of a 3" red wire to eyelet h30 on
PC-8 (S). When soldering to an eyelet on the board,
tin the wire with solder first, and then insert the
wire from above as the eyeld is heated from below.
Make certain that the eyelet is soldered to the
board as well as to the wire lead. Do not allow any
bare wire to show above the board, as it could short
to the volwne control.
22 ( ) Cut a31 12" black wire. Strip one end 3/1" and feed
it through lug #l of the volume control and connect
it to lug #4 of the control.
23 ( Connect one end of an 8" black wire to lug #1 of
the volume control (S).
24 ( Connect one end of an 8" red wire to lug #2 of the
volume control (S).
25 ( Connect one end of a 6" red wire to lug #3 of the
volume control (S) .
26( Connect onc end of an 8" black wire and one end of
a
5" black wirc to lug #4 of the volume control (S).
27 ( Connect one end of an 8" green wire to lug #5 of
the volume control (S).
2R ( Connect one end of a 5" green wi re to lug #6 of the
volume control (S).
29 ( Position the red wire from eyelet #30 down between
the resistors near it and towards socket V6.
30( Slide the tuning dial indicator disc fully onto the
tuning capacitor shaft. The hub goes on the shaft
first, and its flat side engages the flat section of the
brass shaft.
31 ( Mount the front panel to the chassis using three sets
of #4 hardware.
32 ( Connect the red wire from pin #8 of socket V8M to
eyelet #28 (S). On this, and all future connections
to eyelets on the board, make sure that the eyelets
are soldered to the board as well as to the wires.
33 ( Connect the black wire from pin #3 of socket V8M
to eyelet #25 (S).
34 ( Connect the green wire from pin #9 of socket V8M
to eyelet h26 (S).
35( Connect the red wire from eyelet 830 (below the
volume control) to pin #2 of socket V8M (S).
Access to pin h2 can be gained through the front
panel cutout.
36( ) Connect the short black wire from lug #1 of the
volume control to eyelet #37 (S).
3

Assembly 01 the PC· J2Circuit Board
Note that the top of the dched circuit board indicates
the location of each component. The identification symbol
for each part is marked between the holes into which its
leads will be inserted.
It is important that all components be mounted close to
the board. Flow solder from the lead onto the board so that
no ball of solder is evident, but rather a smooth transition
from solder to component lead, and to the board. The
solder must completely surround the lead. Do not apply
excessive solder, but do not hesitate to apply sufficient heat
to assure a smooth flow of solder all around the lead and
onto the board. Be sure that all the eyelets are soldered
to the copper on the board, as well as to the lead. Cut off
all leads close to the bottom of the board after soldering.
1( ) Insert all of the resistors R71 through R93 in their
places on the board. Solder all leads and cut off the
excess.
2( )
Insert all of the capacitors C71 through C84 in their
places on the board. The direction in which these
capacitors face is not important. Solder all leads.
3 ( )
Mount the two 9-pin sockets V71 and V72. Note the
orientation of the flat side of each socket. Ground
straps have been installed in the sockets. Be sure
each pin penetrates the board and does not bend over
on top of the board. Seat each socket firmly to the
board and then solder each pin, the ground straps,
and the center ground pin.
4( Mount the choke L71. Solder each lead and cut off
the excess.
vide a "heat sink" when these are soldered in place.
When soldering them, grasp the loop with a pair of
pliers from the top of the board, and solder from the
bottom of the board. This technique prevents damag-
ing the relatively delicate diodes with excessive heat .
final Assembly
1( ) Install the completed PC-12 board on top of the
tuner chassis in place of the multiplex adaptor cover
plate, using the four sets of #4 hardware. Follow the
orientation in the pictorial diagram.
2 ( ) Twist together the 8/1 black wire (the longer of the
two black wires) from lug #4 of the volume control,
and the green wire from lug # 5 of the control. Con-
nect the black wire to eyelet #82 (S). Connect the
green wire to eyelet #80 (S).
3 ( ) Twist together the following three wires: the remain-
ing black wire from lug #4 of the volume control, the
red wire from lug #3 of the control, and the green
wire from lug #6 of the control. Connect the black
wire to eyelet #77 (8). Connect the red wire to eye-
let 1176 (S). Connect the green wire to eyelet
#78 (S).
4 ( ) Twist together the remaining black wire from lug #1
of the volume control and the red wire from lug #2
of the volume control. Connect the black wire to
eyelet #84 (S). Connect the red wire to eyelet
#86 (S).
5 ( ) Connect one end of a 1 %/1 red wire to eyelet #36 on
the bottom of PC-8 (8). Connect the other end to
eyelet #38 (S).
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6( ) Mount transformer '1'73 (432004). Note that this
transformer can only be mounted one way. Seat it
firmly, so that it snaps into position, and make cer-
tain that all 5 connecting lugs, as well as the two
mounting tabs, penetrate the board. Solder all seven
lugs.
7( )
Mount PEC-l and PEC-2 (555001). Note that these
identical units face in opposite directions. Solder all
6 leads and cut off the excess.
8 ( )
Observing detail B, mount each of the four diodes
D71 through D74. Those supplied may look like
either of those in the illustration, and will have one end
painted red, or marked with three stripes. (Disregard
single green dot..,> or stripes.) DI- ~
ODE POLARITY IS IMPOR- either
TANT. The arrowhead on PC-12 ~
board points to the marked end of - ' -- ,-
the diode. Diodes should be soldered or
carefully without excessive heat, Pf
using the following technique: The -
leads should be bent up, and then
down in the manner shown to pro- DETAIL"B"
5( Mount the transformers T7l and '1'72 (432003). Be
careful to orient these correctly. Make certain that
the pin with the green dot is inserted in the hole
nearest to the heavy dash on the board. These trans-
formers must be seated firmly against the board, and
the two mounting tabs should snap into place. Solder
all 6 lugs (4 connecting lugs and 2 mounting tabs)
on each transformer.
6 ( ) Observe the red and the green wires protruding
through the slot in the front of the chassis. Feed the
red wire through grommet #2 (in line with the slot)
and connect it to eyelet #79 on PC-12 (S).
7 ( ) Feed the green wire through grommet #2 and con-
nect it to eyelet #75 (S). This wire may appear long,
but the extra length is used in the alignment pro-
cedure.
8 ( ) Unsolder the two wires from output socket A on the
back panel. Connect the free end of the short wire
(the wire connected to output socket B) to eyelet
#85 (S).
9 ( ) Cut off 5112" from the green wire just unsoldered
from output socket A (the wire connected to eyelet
#39 on PC-8). Strip the insulation back %" on the
free end, and connect it to eyelet #71 (S).
10( ) Connect one end of a 6112/1 black wire to eyelet #40
of PC-8 (S). Be sure that the solder flows from the
lead, to the eyelet, and onto the copper on the board.
Connect the other end of this wire to eyelet #73 (S).
11 ( Connect one end of a 6" green wire to eyelet #33 of
PC-8 (S). Connect the other end to eyelet #72 (S).
12 ( Connect one end of a 2/1 green wire to the long
(center) lug of output socket A (8). Connect the
other end to eyelet #81 (S).
The remaining steps will require connections to lugs pre-
viously soldered in the construction of the FM-l (unless t
you are building the FM-l and FMX-3 at the same time,
in which case solder will not have been applied). It may
4

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be necessary to clear away some of the solder previously
applied. To make these connections, heat the lug and push
the wire through the terminilL Bc certain that when solder-
ing is called for, all of the wires are finnly soldered to the
terminal.
13( ) Connect one end each of two 6/1 green wires to lug
#1 of the three lug terminal strip. For convenience
of wire location, insert one wire from each side of
the lug. See the pictorial diagram. Solder all wires.
A
total of 8 wires are connected to this lug.
14 ( )
Connect onc end each of two 6" black wires to lug
#2 of the three lug terminal strip. For convenience
of wire location, insert. one wire from each side of
the lug. Solder all wires. A total of 6 wires are con-
nected to this lug.
1.'5 ( ) Twist together the black and the green wire from
the front side of the lug terminal strip. Connect the
black wire to the center ground pin of socket. V71
(S). Connect the green wire to eyelet #74 (S). Posi-
tion the wires as shown in the pictorial.
16 ( ) Twist together the remaining black and green wires
from the lug terminal strip. Connect the black wire
to the center gwund pin of socket vn (S). Connect
the green wire to eyelet #83 (S). Position the wires
as shown in the pictorial.
17 ( ) Connect one end of a 9" red wire to lug #4 of the
quadruple section filter capacitor. Solder all wires.
A
total of 3 wires and one resistor lead are connected
to this lug. Connect the other end to eyelet #87 (S).
The wiring of your Multiplex Integrator is now com-
pleted. It is wise at this point to go back and check all
solder connections in the unit. One poor solder connection
can upset the performance of your unit. Check to· be sure
that the position of the wires in your unit agrees closely
with the pictorial diagram and the photographs. The pic-
torial diagram must necessarily be exaggerated for clarity,
but any discrepancies between it and the photographs are
of no consequence. Make sure you remove all loose pieces
of solder or wire.
Position the red-black and green-black pairs of leads from
the volume control to eyelets #80, #82, 1184 and #86 exactly as
shown in the pictorial diagram, around the V-71 socket and
away from T73. Keep them clear of the board. Insert the
tubes in their respective sockets on the PC-8 and PC~12
boards, and install the tube shields. Make sure the ground
straps on the sockets slip between the shield and the tube.
Insert the EMM-801 tube in the V8M socket.
Now tum the tuner on and allow it to operate for one
half hour or more to allow the tubes to age and for operat-
ing conditions to stabilize. Assuming that your FM-l has
been aligned according to its instructions, you should be
able to enjoy the use of your tuner at this time, and nonnal
monophonic reception should be available at both output
jacks, using the lower beam of the dual-beam tuning eye
for tuning in the stations. The upper beam will be used as
a stereo indicator. A stereo program may have insufficient
separation pending complete alignment, but in other
respects should be satisfactorily received.
If the above conditions are not apparent, refer to the
sedion "In Case of Difficulty" before proceeding with
alignment of the FMX-3.
ALIGNMENT
The Dynatuner should have been aligned according to
the instructions in the manual for the FM-1 before you pro-
ceed with the alignment of the FMX-3. Correct alignment
of the tuner is especially important for proper stereo opera-
tion, and in particular, the discriminator mllst be accurately
aligned according La the instructions in the PM-I manual if
maximum noise rejection is to be realized. It is necessary to
remove the 6BL8 tube from the completed FMX-3, although
the 12AX7 (V72) must be in place when alignment of the
tuner only is carried out. The lower beam of the new dual
beam tuning eye is used in the same way as the EM84 in the
alignment procedures described in the FM-l Dynatuner
manual.
The alignment procedure for your multiplex integrator
is as simple and precise as the alignment procedure for
your Dynatuner. It involves only the peaking of the tuned
circuits for the proper reinsertion of the stereo sub-carrier.
The transformers of the FMX-3 integrator have been presd
close to the proper alignment point. The accuracy with
which the alignment procedure is performed will determine
the stereo separation capability of the tuner, hut due to
variations in the broadcast material, the same degree of
separation will not always be apparent.
The only tool required for alignment is the plastic tool
supplied with your Dynatuner. Only this type of tool
should be used for adjusting the transformers. When using
this tool, all adjustments should be made using the end
which has 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. If you
are careful, it is possible to unsolder and resolder the
required wires in the following steps without turning off
the tuner. However, if you wish to avoid all risk of shock,
you can turn the tuner off, make the connections, and t.um
it on again. It is essential that you give the set afew
minutes to warm up thoroughly after any time that you
tum it off., even if the off time is only a minute or less.
It is suggested that you read these instructions over
completely before proceeding to completely familiarize
yourself with the alignment procedure. If the 6BL8 has
been removed, it and its shield must be reinstalled. The
tuner is to be connected to an antenna, turned on, and
precisely tuned to a known stereo broadcast. The connec-
tion of an amplifier and speaker is not required.
The lower beam of the EMM-801 eye indicates proper
tuning of either mono or stereo. It is designed so that it
does not overlap, but maximum closure indicates the point
of correct tuning.
The upper beam of the eye is the S'TEREOCATOll. It will
close
completely (after alignment) in the presence of the
H:lKC pilot signal which is an integral part of a stereo
broadcast. It will be fully open when a monophonic broad-
cast is correctly tuned, and, depending on ambient noise
conditions, it may flicker between stations.
1 ( ) Temporarily solder one end of the 1.2 megohm
(brown-red-green) resistor R94 to the center ground
pin of V71 (S). Temporarily solder the other end to
eyelet #75 (S). This is one test point, TP. Using
the shoulder end of the plastic alignment tool, adjust
transfonners T71 and T72 for maximum closure of
the upper beam of the eye. Adjust first one trans-
former, and then the other, and repeat. The purpose
of the resistor is to reduce the closure of the eye for
easiest adjustment. Usually only a very small adjust-
ment is necessary to reach the right point.
2( ) Remove the 1.2 megohm resistor from eyelet #75,
and temporarily solder it to eyelet #88 (S). This is
the other test point, TP.
5

5
3 ( ) Unsolder the green wil'e connected to eyelet #75 and
temporarily solder it to eyelet #88 (S).
4( Adjust the top slug of 1'73 for maximum closure of
the upper beam of the eye.
5( )
Adjust the bottom slug of 1'73 for maximum closure
of the upper beam of the eye.
6( Repeat step #4.
7 ( Repeat step #5.
8 ( Remove the 1.2 megohm resistor. This can be saved
for future use when realignment is desired.
9 (
Unsolder the green wire from eyelet #88 and resolder
it to eyelet #75 (S).
This completes alignment of your Dynatuner Multiplex
Integrator. If the brass front plate is being installed for
the first time, its protective plastic film must be peeled off
and it is wise to cut threads in the holes above and below
the tuning capacitor shaft with the two small brass plated
self tapping screws by inserting and removing them. This
will avoid scratching the brass by enabling much easier
insertion when the front plate is installed. Remove the %))
nut holding the volume control to the front panel. Insert
the rectangular plastic insert which is included in the
FMX-3 kit, 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 con-
h'ol
shaft and the tuning capacitor shaft protrude through
both panels. Install the %" 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
7o'clock position. The knob is pushed onto the knurled
shaft. Fasten the large knob onto the tuning capacitor shaft
by tightening the set screw. Install the rubber feet in the
corner holes of the bottom plate, and secure the bottom
plate and the cover with the four sheet metal screws. The
flange on the front of the cover goes between the steel
front panel and the brass front plate.
Your Multiplex Dynatuner is now ready for long pleas-
ureable use.
IN CASE OF DIFFICULTY
Your FM-l Dynatuner manual has some trouble shooting
suggestions (page 13) which are applicable to the complete
stereo tuner. In addition, it is frequently possible to locate
difficulties by using the voltage table in this manual. A
vacuum tube voltmeter is required. Departures of more than
20% from the indicated values (except for voltages
marked ,:,) indicate apossible error or component failure.
Some understanding of the FMX-3 circuitry will assist
in troubleshooting. Review the circuit description at the
beginning of this manual. In addition, the STEREOCATOR
(upper beam of the EMM-801) will aid in locating the
difficulty. The STEREOCA1'OR is operated by the 19KC
amplifier and doubler circuit (1'71, Tn, V71). Remember
thai in most cases, if the EMM-801 socket has been correctly
wired, improper indication by the STEREOCATOR is an
effect, rather than acause.
If the STEREOCATOR remains closed on both mono and
sicrc>o stations, the 19KC amplifier is oscillating. Arough
check of the STEREOCATOR is to disconnect the green
wire from
eyelet #75 and touch the free end with the finger,
which
should illuminate the word STEREO.
6
If the STEREOCATOR passes this test, but does not
deflect on aknown stereo broadcast, check the 6BL8, and
also check the continuity of 1'71 and Tn with an ohmmeter.
The resistance of each transformer pin to ground is approx-
imately as follows: #1 pin-On, #2 pin-40n, 113 pin-IOn.
#4 pin-100ft The #1 pin is identified on the board by a
white mark (green dot on the can) and the pins are num-
bered clockwise when looking at the bo/.tom of the board.
If the STEREOCATOR is operating correctly, but there
is little or no separation on aknown stereo broadcast, make
certain that the fault does not lie in the broadcast. Program
material or transmission deficiencies are common causes of
such complaints where stereo programming is relatively
new.
Separation may also be adversely affected by "multi-
path distortion"--reflections of the signal by buildings, hilly
terrain, etc., which cause effects similar to television
"ghosts," often accompanied by distortion of the audio sig-
nal.
Multipath effects can be reduced only by improving the
antenna system-relocation, reorientation, or replacement
with a more directional antenna.
If it has been determined that poor separation is caused
by the FMX-3, and the STEREOCATOR operates nor-
mally, the T73 transformer may be incorrectly aligned,
although 1'71 and 1'72 should also be checked. Incorrect
alignment can also cause channel reversal. Normally, the
A output jack is the left channel.
A diode which is faulty, or one which is installed incor-
rectly may also reduce the separation, but this will usually
be accompanjed by a significant reduction in output on the
affected channel.
If the 6BL8 tube is removed, there will be no separation,
and the STEREOCATOR will not light, but monophonic
transmissions will still be normally received with equal out-
put from the A and B output jacks. If these signals are un-
balanced, or if one channel is distorted, the difficulty is in
the diode bridge or in the V72 circuit.
If the stereo alignment procedure can be carried out with
eye deflection at both alignment points, it is probable that
the 19KC and doubler sections are functioning properly. If
there is no audio signal when there is deflection of the upper
beam of the EMM-80l when tuned to a stereo broadcast,
then the signal path should be checked from eyelets #33 and
#39 through choke L71, to 1'73, through the diode bridge to
the dual volume control and to pins #2 and #7 of vn. Touch-
ing the circuit at any of these points should produce a pop or
hum through the system. If not, something in this path is
malfunctioning.
FACTORY SERVICE AND GUARANTEE
It is recommended that the entire Dynatuner with
FMX-3 installed be returned to the factory for service
should service be required. Rpmoval of the FMX-3 for serv-
icing is
generally not practical since its performance is
interrelated with that of the Dynatuner, and both should
be examined as an entity.
Please refer to the FM-l manual for factory warranty
and service on the FM-l. This section is applicable to the
FMX-3 without additional charge for service of the multi-
plex portions of the circuitry.
Dyna Company assumes no responsibility or liability
for damages or injuries sustained in assembly or operation
of the FM-l and/or FMX-3.
I
I

VOLTAGE CHECK POINTS
All voltages are measured between the point indicated and the chassis, using a vacuum tube voltmeter. All voltages are
measured with volume control at maximum. STEREO voltages are measured when tuned to a station known to be transmitting
astereo signal. QUIESCENT voltages are measured with V6 removed from its socket to obtain quiescent condition of the
FMX-3 and the tuning eye. Voltages indicated by ("') vary with signal strength but should always be negative.
PIN #
TUBE
CONDITION 1 2 3 45 6 7 8 9
QUIESCENT 0205 0 0 6.3
AC
29
-.64
53
-.6
V 8M EMM801
STEREO
0200 0 0 6.3AC 180 -14*
150
-7'~
QUIESCENT 29 078 6.3 AC
072 11.5
-.15
V71 6BLBjECF80
STEREO
45 0 71 6.3AC 064 1.1 1.1
-14*
QUIESCENT 135 0.85 00135 0.85 6.3AC
V72 12AX7jECC83
STEREO
135 0.85 0
()
135 0.85 6.3AC
PARTS LIST
....
The parts listed here are in addition to the parts list included with the pictorial diagram of PC-12. Acomplete inventory
will include both sections. Parts of similar type which do not change performance may sometimes be included as a matter
of expediency .. This will account for slight variations in value and appearance.
1 Etched circuit board PC-12
1 Dual volume control, 250,000 ohms per section
1 Plastic insert for front plate
1 Audio cable shielded
3 Pieces hook-up wire (red-black-green)
1 9 pin tube socket with flange - V8M
1 EMM801 tube - V8M
1 Instruction manual
1 Warranty card
CAPACITOR
C 41M 470 mmfd
RESISTORS
R 20M 100,000 ohms brown-black-yellow
R 30M 22,000 ohms red-red-orange
R 35M 18,000 ohms brown-gray-orange
R 39M 22,000 ohms red-red-orange
R94 1.2 megohms brown-red-green
•0
S8 t8
12AX7
Ia
18
ClI
Z8
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-lBI--
tll~
-98H-
-S8H-
08
m
I
98
-99H-
-16H-
I
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,
-06H-
£L
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-£6H-
6L
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tLO
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~!88
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IC
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-t8lI-
£w
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6f
,
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-SLH-
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fiLa 9L ~\
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\IIj!
DLI
III
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-9LH-
II
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I Lf~
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d1 SL
L\ BL
lfl
6BL8/EC~
-LiH-
00
(0
0
7

-e-
100,000 ohms
22,000 o~ms
18,000 ohms
22,000 ohms
18,000 ohms
240 ohms
22,000 ohms
47,000 ohms
150,000 ohms
1.2 megohms
3.3 megohms
2,200 ohms
220,000 ohms
150,000 ohms
47,000 ohms
47,000 ohms
47,000 ohms
47,000 ohms
100,000 ohms
100,000 ohms
1,000 ohms
1,000 ohms
100,000 ohms
100,000 ohms
470,000 ohms
470,000 ohms
470,000 ohms
1.2 megohms
470 mmfd
500 mmfd
220 mmfd
.012 mId
.0068 mfd
SOO mmfd
.001 mfd
.0033 mfd
.0015 mId
.01 mfd
500 mmld
100 mmfd
.1 mfd
.1 mId
18 mmld
IN 54!
IN541
IN541
IN541
53 mh choke
transformer =432003
transformer = 432003
transformer =432004
£MM801
6BL8j£CF80
12AX7 JECC83
module =555001
module =555001
PARTS LIST FOR
SCHEMATIC DIAGRAM
V71B
R94
R92
TP
Rn
SCHEMATIC DIAGRAM
RS8
, -=-
V72B
074 R84
D72 R82
PEC-2
":;"
ll'\'" '-.../ \ll'~
\(\~ \~
\- I 250K ~ j
- OUALCONT. -
R73
R74
R75
C74
R72
~OP
IT
I~
!
~
2I • I 2
R80
-=-
R81
R83
(88)TP
'r
C84
V71A
C79
J
RS9
-=-
l71
5
C80
r
4 ~
I
I
I
I
I
I
I
I
R20MI
I
I
I
I
V7B
1
6.3 VAC
-=-
R39M
V7A
I • (33) . (
r---.~ I (79~
---I' -~,-;::;::--~.L----~
I
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TP
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