SERIAL NUMBER . I 15350075 This number must be mentioned in all communications concerning Dynakit. STEREO CONTROL AMPLIFIER. INSTRUCTIONS FOR ASSEMBLY AND OP.ERATION .. , Price Patented $1.
• • •• 1) 5 6 7 9 SPECIFICATIONS Inputs: 7 pairs: RIAA magnetic phono low level, magnetic phono high level (50,000 ohms); Ceramic phono; NAB 71j2 i.p.s. tape head (100,000 ohms); radio, tape, spare (250,000 ohms) Outputs: Constant level tape output, 8 and 16 ohm loudspeaker outputs, center-channel loudspeaker output, provision for headphone connection. Controls: Selector, Volume, Balance, Bass, Treble, Stereo-Mono Switch, Loudness Compensation Switch, Filter Switch, Power Switch.
INSTRUCTIONS FOR ASSEMBLY AND OPERATION OF THE DYNAKIT SCA-3S STEREO CONTROL AMPLIFIER The SCA-35 is a high quality stereo preamplifier and amplifier combination which serves as a control center for various program sources such as phonograph, tape and radio. The SCA-35 permits selection of the program source desired, modification of the tonal characteristics of the sound source, and change of volume; it provides output connections for loudspeakers and headphones.
BACK PANEL CONNECTIONS Phono Connections through the SCA-35, the track recorded in the opposite direction will come through one channel of the SCA-35 unless one of two expedients is used to prevent this: (1) One cable can be removed from the unwanted chann*, then by using the mono position of the stereo-mono swit~) the sound will come through both speakers, or (2) Thebalance control can be turned to either extreme position to eliminate sound through the unwanted channel.
L Other Back Panel Connections There are two AC outlets on the back panel to which the wer cords of auxiliary equipment may be connected. One these outlets is switched in unison with the SCA-3S when e SCA's power switch is operated. The other outlet is not switched and will furnish power at all times that the SCA's power cord is plugged in. The switched outlet may be used to power a radio tuner so that this can be turned on and off with the SCA-3S.
Connection of the center speaker is accomplished by removing the wire link, or jumper, which connects the leftmost screws on the two loudspeaker terminal strips and connecting the two wires from the extra speaker to these two screws. The diagram below also shows how a volume, or level setting, control can be optionally added to control the level of the center speaker. The control itself is a 4 watt, wirewound, potentiometer or rheostat. They are available at all radio parts supply stores.
TECHNICAL DESCRIPTION The DYNA Stereo Control Amplifier, SCA-35, is a comlete stereo preamplifier and stereo power amplifier comed on a single chassis with a single power supply. The SCA-35 uses new circuitry and new components in a unique arrangement which provides highest quality performance ill a compact and moderately priced unit. Superficial examination of the circuit of the SCA-35 might indicate an apparently simple and conventional design.
The only procedure involved in building a Dynakit which requires a bit of technique is soldering, and this is quite easy to master. There are four steps to making a good solder connection: 1. Make a good mechanical connection. 2. Heat both parts of the connection with the iron. 3. Apply solder to the connection until it melts and runs. WRONG 4. Allow the connection to cool undisturbed. ALL SOLDERING MUST BE DONE WITH ROSIN CORE SOLDER.
fRONT PANEL MECHANICAL ASSEMBLY 1 ( /) Place the front panel before you so that its "wings" are facing you, with the rectangular switch cutouts at the bottom~ as in the pictorial diagram. Refer to the pictorial diagram before and after each step to be sure that you are proceeding correctly. Install the pilot light socket at the extreme left end of the panel with a #4 screw inserted from the outside, and a lockwasher and nut from the inside (the side of the panel which is toward you).
18 (~ Connect PEC lead # 1 to treble control lug # 1 (S). 19 ( '1' Connect PEC lead #2 to treble control lug #3 (S). 20 ( ,) Connect PEC lead # 3 to bass control lug # 1 (S). 21 (~ Connect PEC lead #4 to bass control lug #2 (S-3). _22(..{Connect PEC lead #5 to bass control lug #3 (.8). 23(,,1) Connect PEC lead #6 to balance control lug #3. 24(~ Connect PEC lead #7 to volume control lug #2 (S). 25 ( v('Connect one lead of a 10 of capacitor to filter switch lug #1.
REAR PANEL WIRING 1( 13 ( short lugs between sockets #9 and # 10 (8-3). Twist this wire together with the two red wires connected to lugs #9 and # 10. ~There are a total of sixteen input sockets on the rear panel; the center (long) lug of each socket has a number, shown in the pictorial diagram. Connect \, one end of a 1112" black wire to the pair of short lugs between sockets #1 and #2. Connect the other end to the pair of short lugs between sockets #3 and #4 (8).
MAIN CHASSIS MECHANICAL ASSEMBLY 1 (~ss the leads of one of the output transformers Z-565 through the two holes provided nearest the front of the chassis (see the pictorial diagram for the correct location). The leads of the transformer are in two groups: the orange, black, and yellow leads which pass through the rear chassis hole; and five other leads which pass through the front hole.
#4 of terminal strip TS-2. Connect the green-andwhite lead to lug #5 of TS-2. NOTE: These transfonner leads should be inserted into the eyelet that holds the tenninal to the strip, thereby providing more space on the lug for the other wires to be connected. 12 (nhe silicon rectifier diodes supplied with the kit may be any of the three types shown in the illustration; UJ Cl UJ although different in appearance, O~Cl they are electrically equivalent. Con- .~~~.
41 (vf Twist together a pair of green and black wires, each 2%" long. Connect one end of the black wire to lug #1 of terminal strip T8-2; connect the other end to pin #5 of V-6 (8-2). Connect one end of the green wire to lug #2 of T8-2'. Connect the other end Jof the green wire to pin #4 of V-6 (8-2). 42 ( ~ Twist together a pair of green and bla<;k wires, each 10%" long. Connect one end of the black-wire to eyelet #9 on PC-11 (8). Connect the same end of the green wire to eyelet #10 on PC-ll (8).
18(y(Connect the green wire from the stereo-mono switch to lug B-lo 19 ( ~ Connect the black wire of the red-and-black twisted pair from the balance control to eyelet #6 on the ,'. front PC-10 (8-2). This is the second wire con. nected to this eyelet. Connect the red wire of this pair to eyelet #7 (8). 20 ( ~ Connect the black wire of the green-and-black twisted pair from the balance control to eyelet #6 on the rear PC-10 (8-2). This is the second wire . connected to this eyelet. Connect the green wire of .
PLACES TO DOUBLE-CHECK AFTER WIRING Be sure that all mounting screws and nuts are tight. Compare the wiring of each of the tube sockets to that shown in the pictorial diagram. All connections should be securely soldered, with enough space between connections to the tube socket connecting lugs so that there is no chance of an accidental short-circuit. Compare the wiring to each lug of the filter capacitors to that shown in the pictorial diagram.
for 240 Volt Operation 1 ( ) Connect the violet-and-white lead to lug # 1 of terminal strip TS-l. ) Connect the black-and-white lead to lug #1 of terminal strip TS-1 (S-2). 3 ( ) Connect the black lead to lug # 1 of AC outlet B (S-2). 4 ( ) Connect the violet lead to lug A on the fuse . holder (8). When using the 240 volt connection, a one ampere sloblo fuse should be used instead of the two ampere fuse recommended for the 120 volt connection.
Both Channels Not Working Should neither channel function, there is the possibility that a similar mistake has been made in the wiring to both sides. This is an unlikely situation, but it should be checked by visual comparison of the wiring with the diagrams. Generally, the cause of malfunction of both channels together lies in the one section of the unit which is common to both channels - the power supply. The checking of this section is covered earlier.
_i R 1 R 2 R 3 R 7 R 8 R 9 R 10 R 11 R 12 R 13 R14 R15 R16 R17 1.2 megohms 150,000 ohms 1 watt 5% 5,600 ohms 5% 120 ohms 1 watt 5% 120 ohms 1 watt 5% 1.2 megohms 47,000 ohms 390 ohms 18,000 ohms 5% 100,000 ohms 5% 47,000 ohms 1.5 megohms 1.2 megohms 150,000 ohms 1 watt 5% 5,600 ohms 5% 120 ohms 1 watt 5% 120 ohms 1 watt 5% R 18 R19 R20 R21 R22 R 23 R24 R25 R26 R27 R 28 R29 R30 R 31 R32 R33 R34 All resistors are Y2 watt, 10% unless otherwise noted. 1.2 megohms R 35 470.
SCHEMATIC DIAGRAM Silicon rectifier, 500 ma, 1000 PIV 2 Silicon rectifier, 500 ma, 1000 PIV 'olume control-250,OOO ohms lalance control-750,OOO ohms lass control-2 megohms reble control-500,OOO ohms lum control-l,OOO ohms , 1 12AX7/ ECC-83 , 2 12AX7/ECC-83 , 3 7199 , 4 7199 , 5 6BQ5/ EL-84 , 6 68Q5/ EL-84 , 7 68Q5/ El-84 , 8 6BQ5/El-84 ~_-.-'V..::.:[L~ 16il )o-_+,O=.::A~ 8il c IART 5 i.3 At --, U AC --, ;,3 At ~----'T"""'" '----;f-8,LK 6 7 8 10~ 0 .25 .
FACTORY SERVICE AND WARRANTY The SCA-35 is designed to provide reliable, trouble-free perfonnance for a long period of time, when properly assembled and installed. It is intended for use with the 120-volt AC power supplied to most homes. Although variations of several volts above or below this figure will have no pronounced effect upon performance or component life, the nonnal guarantee on the equipment is not applicable if it is operated with AC inputs greater than 130 volts.
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