Dynaco FMA2 pwr sm

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Dynaco FMA2 pwr sm

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Page 1


This number must be men-

F MA_2 I NS E RT iioned in all tommunica-
tions concerning Dynakii.


Price 50¢

DYNA COMPANY EJJWJAMJ :2::A::"::.1°1f:::

Page 2



The Dynakit FMA-2 is a semi-selfpowered 10 watt
amplifier designed to fit inside the FM-l Dynatuner. It
occupies the chassis cutout presently provided for the
Dynaeo multiplex adapter. This amplifier provides full
high fidelity performance within its power rating. convert-
ing the Dynatuner into a complete FM radio (less loud-
speaker). At the some time. the tuner can still function
independently as an ultra sensitive, low distortion, wide
band tuner.

The performance of the FMA 2 is on a quality level not
normally found in amplifiers of low power rating. lt pro-
vides 10 watts at less than 1% distortion within 1 db from
30 cycles to 15,000 cycles. Its frequency response is 1
db from 12 cycles to 35.000 cycles. Transient response is
excellent, permitting clean transfer of 10.000 cycle square
waves and critically damped low frequencies.

A unique power supply configuration borrows power
from the present Dynntnner power supply. Using additional
silicon diodes to obtain a negative voltage. Operating volt-
ages in the Dynatimcr are unaffected by operation of the
FMA 2 because the power supply of the FM-l tuner was
designed with extra load capacity. The GBQ5/El.84 output
tubes operate with the inverted power supply. A .l2AX7
voltage amplifier and phase inverter stage, uses the FM-I
power supply, an arrangement which completely eliminairst
undesired coupling betwem low and high level amplifier
stages. :he use of a miniaturized high quality output trans-
former ot' patented Uynaeo design permits a high feedback
[actor and low distortion over a wide band.

The FMA-Z can be used with its own loudspeaker while
audio signals may be taken from the A output socket to
feed an amplifier I'with or without preamplifier) and
another loudspeaker. It is also practical to use the Wynn-
tuner to furnish signal to an external multiplex adaptor
(see the Appendix of the FM-l instruction manual) inde-
pendently of the use of the FMAQ. There is no harm in
removing the loudspeaker connected to the FMA»2 and
using the Dynatuner in normal fashion. The amplifier is
designed so that it can operate without a speaker


You will first assemble the etched circuit board, and
then mount it and the other components on the chassis of
your Dynatuner and complete the wiring. Note that the
top of the etched circuit board diagrams the position of
each component~ The identification symbol for each part is
marked between the holes into which its leads will be
inserted. Resistors may be identified by comparing them
with the color code provided on the parts list. The first
color is nearest the end of the resistor, and any fourth color
band should be ignored. Capacitors will be individually
identified. Other special components will be identified as
they are called for in the assembly process.

It is important that all components be mounted close to
the board. Refer to the FM 1 instruction manual for
detailed instmctions on proper wiring and soldering tech-
ROSIN CORE SOLDER. Whenever soldering is required,
the instructions indicate it by "(S l If this symbol is not
shown after a connection is specified, it indicates that
further connections will be made at that point before

When soldering a part to the etched circuit build. new
the solder from the lead onto the board so that no ball of
solder is evident, but rather a smooth transition from sol
der to component lead. and to the board. The solder must
completely surround the component load. 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 terminals are soldered
to the copper on the board, as well as to thr- lead. Cut ofi
all leads as close to the bottom of the board as pomihle,
alter soldering. This is essential. since the clear continua cf
the tuner allow only 1/," clearance from the board to the
EMA-2 chassis.

PC-9 Etched Circuit Board Assembly

U. ) Mount all of the one-hall watt resistors. RF? through
R62. onto the board. Keep them flush against the
board. Solder all leads and cut off the excess close
to the board.

21' 1 Mount the one-watt resistor R63 and the threwwutt
resistor R64. Solder each lead and cut ofi the excess
close to the board.

3. 5 Mount the small capacitors CSl. C56 and C57. Keep
them right against the board. Solder each lead and
cut off the excess.

44 l Mount the rectangular capacitors C52. C53, CS4.
055 and (158. Solder each lead and cut off the
excess. The direction in which these capacitors face
is not important.

5( l Mount the connecting terminals #51 through #64.
When the small end is inserted in the hole, they
snap lightly into place. Solder each, and cut the
excess ed on the bottom (copper side) of the board.

6( ) Mount the three 9 pin sockets on top of the board.
Note the orientation of the flat side of each socket.
Make sure each lab penetrates the board, and bend
the tips over for a secure mechanical connection.
Solder each pin carefully. Note that in use, the
tubes will plug into the bottom of the sockets, on the
side of the board opposite to that on which other
components are mounted.