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Page 1: ...o Com p LF ELECTRONIC CDRPDRATIDN MODEL ASC 305 B Stereo Control Center TECHNICAL MANUAL 5851 FLORIN PERKINS ROAD SACRAMENTO CALIFORNIA TELEX 377 488 CABLE SPARTA 916 383 5353 A Division of Computer E...
Page 2: ...tained herein Neither this document nor the information contained herein shall be disclosed to others for manufacturing or any other purpose except as authorized in writing by Sparta Electronic Corpor...
Page 3: ...om the ASC 305B PREAMPLIFIERS Preamplifiers are located on the lower she lf one on each side and feature separate level controls for left and right channel output These are preset for proper level but...
Page 4: ...us motor driven turntables Another section provides additional information TONE ARMS The ASC 305B is supplied standard with SPARTA ST 220 Professional Stereo tone arms and are designed so highly accur...
Page 5: ...lifiers in channel 1 plus stereo equalized phono preamplifiers for inputs to channels 2 and 3 TONE ARM The SPARTA Model ST 220 Professional Stereo Tone Arm reflects the high quality and scientific des...
Page 6: ...ta is contained herein Neither this document nor the information contained herein shall be disclosed to others for manufacturing or any other purpose except as authorized in writing by Sparta Electron...
Page 7: ...lbs 6 lbs 16 Wide 15 1 2 deep 5 1 2 GT 12 4P 6 1 2 GT 12 SY 2 1 4 without tone arm 2 3 4 with ST 220 12 33 1 3 and 45 rpm Less than 1 16 turn at 33 1 3 rpm 45 db below reference level of 1 4 centimete...
Page 8: ...ssure between motor pulley idler and table rim INITIAL ADJUSTMENT IS AS FOLLOWS Screw in clockwise 45 RPM screw until motor ceases to drive table then back out screw slowly until just enough pres ure...
Page 9: ...the driving surface of the idler and the inside rim of the turntable be kept clean of oil or other contaminating substances During the first few weeks of operation the idler driving surface and the in...
Page 10: ...ction with the problem such as serial number of table date purchased whether problem is new or of long standing type of pickup and arm used whether problem is different at different table speeds wheth...
Page 11: ...force for any cartridge ARM HEIGHT ADJUSTABLE Locking screws on shafts of arm and rest adjust height of arm from 40 60 mm 1 9 16 2 3 8 CARTRIDGE SHELL REMOVABLE Uses international standard 4 pin conn...
Page 12: ...www SteamPoweredRadio Com Models TEP3S and TEP3M Turntable Preamplifiers...
Page 13: ...14 dbm typical DISTORTION Less than 0 1 0 03 typical THD INPUT IMPEDANCE 47K ohms Can be changed SENSITIVITY 5 millivolts for 1 dbm output at 1 KHz NOISE 70 db below Program Level More than 80 db belo...
Page 14: ...mating socket and carefully remove any remaining flux or rosin before engaging the connector Additional information will be found in the following1 DESCRIPTION section under output A common cause of R...
Page 15: ...formerless para phase inverter which avoid the problems associated with cascaded output and input transformers This contributes significantly to the excellent equalization and freedom from ex traneous...
Page 16: ...ity In addition the s n ratio of the IC is equal to or better than can be obtained in discrete designs which leaves t he noise performance primarily dependent upon the resistors used in the external c...
Page 17: ...were set for higher sensitivity then operation with a high output cartiridge would provide more than dbm output and seriously decrease the available headroom for program peaks If the output level of...
Page 18: ...ront panel ground stud The stud i s provided for the separate tone arm shell ground lead which is ofte n provide d and is also the proper place to connect the turntable frame ground Tone arm to preamp...
Page 19: ...n be determined by shorting the preamp inputs with shorting plugs If the hum disappears it was introduced before the preamp Similarly disconnecting the preamp output plug will determine if hum is comi...
Page 20: ...dge is terminated in a higher than optimum impedance undesirable high frequency peaking will result If a lower value is used however the terminating resistor with the cartridge inductance will result...
Page 21: ...ilter capacitor C2 This voltage will vary between mono and stereo unit s and also vary with input line voltage Proper operation can be expected with as low as 34 t o 36 volts however so long as this v...
Page 22: ...13 wer s u pply from reaching Q2 a nd appearing in the output a nd also causes a slow turn on characteristic Rl limits the peak current through the diodes at turn on and also limits the power dissipa...
Page 23: ...open If the bias voltage of Q l or Q2 i s much more than 0 6v each then either a base or an emitter must be open b Voltage across C2 lower than normal would indicate excessive load current and sugges...
Page 24: ...very likely that Q3 has an emitter to collector short It can be seen by the examples given that the basic approach in transistor servicing is one of determining if the transistor h s normal emitter to...
Page 25: ...d in phase with the input signal The IC op amp used in the TEP 3 series has a typical open loop gain of 20 000 so the output will try to be 20 000 times larger than the input signal If the output sign...
Page 26: ...so or one half of the voltage at pin 14 of the IC through divider R3 R2 This voltage also appears through Rl as an input voltage to the IC so the output at pin 1 swings towards the supply as fast as i...
Page 27: ...easure t he 1Joltage at pin 5 and then check to see that pin 1 has the same voltage If the output voltage is high the next check is to see if this voltage is getting back to pin 6 Incidentally these m...
Page 28: ...the closed loop gain decreases accordingly So it is apparent that the gain and frequency response are determined strictly by the values and tolerances in the feedback network primarily RG R7 CG and C...
Page 29: ...input exactly In the TEP 3s the nominal open loop gain is 86 db whereas the maximum closed loop gain is slightly over 60 db This assures a minimum of more than 20 db of feedback which accounts for th...
Page 30: ...ut Right output Comrr on See Note Left output Left output In balanced lines the shield is normally left floating at the audio source and is connected to ground at the audio console But if RFI is exper...
Page 31: ...www SteamPoweredRadio Com SPARTA AS 30B AUDIO CONSOLE...
Page 32: ...Z load Phones 1 mw nominal into l0K ohms FREQ RESPONSE All outputs less than 2db down 20 Hz to 20 kHz NOISE DISTORTION CROSSTALK POWER SIZE SHIPPING WT MUTING NOTE l NOTE 2 Below 65 db at vu out with...
Page 33: ...sources intended for single ended high impedance loads the minus input terminals of the consoles are connected to the shield and the console now appears as a single ended high impedance lOK load The...
Page 34: ...37 stranded or 8739 solid Either may be used although it is generally more satisfactory to use solid wire in a permanent installation where flexibility is not required since solid wire is easier to ha...
Page 35: ...nent installation wrere _ flexibility is not required since solid wire is easier to handle and less apt to inadvertently short to an adjacent terminal Single ended outputs and inputs can y se the same...
Page 36: ...for an 8 ohm load although they will operate equally well with a 4 ohm load or two 8 ohm speakers in parallel with slightly increased power output capability If the load is higher than 8 ohms power o...
Page 37: ...und is only completed when the mixer control lever switch leaves the off position In the A 15B Console this lever switch selects the A B inputs to each mixer and the C position does not exist so the c...
Page 38: ...0 to 1 dbm depending of course on the sound level and microphone used In a normal situation then the preamplifier output is at essentially the same level as the high level input signals resulting in a...
Page 39: ...via the input cables Mixing takes place by feeding the output of each mixer potentiometer through a high value series resistor l0K or 27K to a common mixing bus which in turn leads to a mixing amplif...
Page 40: ...program to substantially the same level as originally fed to the mixer pots with the mixer pots at their usual operating positions about one o clock Since a current mixer operates from a relatively hi...
Page 41: ...t transformer must be isolated from the line with a pad typically 4 db t o prevent interaction with line reactances Finally the line amplifier output impedance must properly match the line transformer...
Page 42: ...source is the line transformer output ahead of the line pad which allows an added 4 db of attenuation in the meter pad for increased isolation A balanced H pad is not required since the meter need no...
Page 43: ...DESCRIPTION GENERAL stage of the program line amplifier Since there are no active or non linear components to follow the monitor provides constant assurance of both level and quality whereas the VU m...
Page 44: ...nd excellent overload characteristics With normal microphone input leve ls the output level to the mixer will be approx 0 dbm The maximum output level of the 1018 before clipping is in exce ss of 14 d...
Page 45: ...the feed back to the emitter of Ql is in phase with the signal input to the base of Ql This consitutes negative feed back since the feed back attempts to cancel the input signal The open loop gain wi...
Page 46: ...r voltage of Q3 is set by the collector voltage of Q2 and since the collector current of Q2 is also the emitter current of Q2 a ny change in the collect or voltage of Q2 a l so appears as an inverted...
Page 47: ...the supply or towards ground If the operating point is beyond the limit given but still capable of moving further in either direction the amplifier will still be operative it simply will not have as...
Page 48: ...mixers through high value resistors of l0K ohms or more Each input current then follows the path of least resistance into the mixer amplifier independent of the condition of the other mixing channels...
Page 49: ...or voltage R3 then forms a negative feedback path which assures that Ql s operating point remains within a reasonable range Normal operation of Ql will be obtained at any collector voltage between app...
Page 50: ...ough a resistor R7 which is ten times larger than RB so it must cause ten times the voltage change The voltage gain of 02 then must simply be the ratio of R7 to RB or ten In normal application Q2 is l...
Page 51: ...n only rise to the poir1t where the combined feedback currents from R3 and R6 approach cancellation of the input current with hthe current through R6 being domil ailt Very low distortion results typic...
Page 52: ...4 is compared to the input signal at the base of Q3 thereby setting the ac gain When power is first applied Cl3 must be charged to one half of the supply voltage through Q6 and to protect Q6 the charg...
Page 53: ...ill change due to the rising reactance of 13 This change will appear as an error signal when compared with the input and allows the reserve open loop gain of the amplifier to correct the error thereby...
Page 54: ...a good match for the 60 ohm primary of the line output transformer The transformer produces 10 db of voltage gain which is followed by a 3 db loss in a resistive isolation pad The rms signal voltage a...
Page 55: ...d be most suspect since subsequent gain is the highest Hum 120 Hz would of course lead one to the power supply Distortion will be practically non existent if normal de and ac gain is obtained The line...
Page 56: ...t 12 TPA 4 2 AMP TPA 4 2 AMPLIFIER 3 27V C4 Z lp RS 7 ca 11101 N R3 IC IK J I N4UU Jr Qs V T 0 1 250 1 1 6V 02 IN4O0ll 3 II I L I I I r 1 2 iJ 3 Cl so I 1 t A TA ELECTRON IC CORPORAT ION SACRA II EN...
Page 57: ...C QI c s 1 0 C4 I S 1 RZ4 I 100 t 2 w I 2 7V C l4 soc f R1 J 55VOC t 1K es 6 81 12 16 I cs C1 8 1 0 Q2 Re 15K RI t10 a 2 All 1801 TO IIASTER 8AIN CONTROL R9 12 0I RIO ISOIC ca I IBK I Rl ll 151 C9 33...
Page 58: ...voe W t4 voe I R3 Cl _J_ 82 K l T T 201 C9 1069 1 3 3 h s I IT 82K C4 T l0Q0pf 6 I c t I t I i 180 I I RI R2 39K I 20VOC I 680 R4 7 S K C2 47p 2 138 I l I d J I NS138 r 1 H telC6 T fi cs l000pf r ll h...
Page 59: ...12 4dl Pod i 62 62 I 8 9I 1 2 K 62 62 I L J 7 11 To mete p od ood VU me e LINE O UT 4 0 0 6 10 GND ri mory 60 ohm Secondo Y 600 ohm ldb 20Hz to 20 KHz ot 24dbm Resistor s i W 5 I SPART A ELECT RON IC...
Page 60: ...www SteamPoweredRadio Com 4 7K 1 8K Input 3 3K Al I resistor s W 5 SPARTA ELECTRONIC CORP 905 METER PAD Drown I Che ked I Cote I R vi ed I Numb mu I t f n I 1n o I I I...
Page 61: ...f35y 1 2K 11 _ IC 12 13 02 I 2 v o c 1 8 i __ J Rl S R17 820 18K 5 30 33 r J3 3 SHIELD R28 820 S 7o C21 50 25v RIGHT 1 2ovoc I I J3 1 t_ r QS R30 R21 R22 100K 1 5M 02 18K J2 I 5 5 o o f 1 2 K C17 C18...
Page 62: ...n 1 sec 02 3 4 0 3 4 VAC 4OMA Refer to circuit de cript ion 01 02 O SA I00PIV lN 4002 or equiv 03 1NS2SB 22V 4C0M W 5 Rl 6 8 lW j 40Vnom j C2 I R 100K R3 100K cf Q2 2N2102 2N2102 Ql l 31 2 3OV 1 R 4 2...
Page 63: ...power cable used when external device is operated by PS 6A supply 2N3054 1 R2 3 9K I 29 2V I2 6V T 1N963A Zl2 OR 1N524A 103 BOARD 7 28V I 1 R3 3 R4 1 8 K 1 Q I s I I I C4 RS 5 6K 4 l 35 R6 I I l cs 1...
Page 64: ...TIO OPTIONAL 620 ohm TERMINATION RESISTOR USE WITH l 0K BRIDGING TRANSFORMER ONLY TERMINATING RESISTOR 620 ohms REQUIRED W ITH 600 ohm TRANSFORMER ONLY 9 MIXER POTENTIOMETER 7 COMMON GND SPA RTA ELECT...
Page 65: ...C R Ow i H R 23 eJ E R 114 tM lf HUCt 08 A J U r l UI r lie j 0cT I 1 r c J 1 o A J I I I I I I I YO POWII oc I C oc oc I ti oc u LU _ I I I I I I OWII IWlt M ___ 1 MC UfOI IOUt CI eo 11 _____ I I I A...
Page 66: ...dio Com iTl EFT S PE D C NOWIR E I TEP3 CS LEFT SIOE A C SOCKET G ND WIRE INPUT s i MUTE MON t cDE MC 1 TT2 R HT S DE RIG Hi SIDE I ci AC SOC t i C NO W RE i E P S CD t c I 00 c J l_ T R AO S 2 oX MON...
Page 67: ...E 0 ACS 305 LEFT INPUT _r 4 V t A Mt EN0 1 MP J 4L RED eLIJ l 3 2 50 t TRIAD S 23X 8RN A5 30B MONITOR C Ue pE P E R BLK L EfT MON RIG HT MUTE1 51 IELD AMPr E OL l MPMC OL FI EP BlK s oeo ToL 5 DEiE 3...
Page 68: ...RIG i CH ANNEL INPUT TONEA R M AN D TURNTP e LE G ROUND Ol TPUT S rRON VlE W NOTE CL EP N E CE SS SOLDE R AND A LL FLU X OR R 05IN FROM PLUC S eiE FORE N5ERTI ON COMMO N 5H E LDS 25 tf mcr TEP 35 AND...
Page 69: ...ion transformers reactors and filter chokes carry an extended warranty of 50 of the replacement cost being allowed should failure occur during the second year The foregoing express warranty does not a...
Page 70: ...RIMPED LEAD VERSION ONLY H 238 258 278 278 298 338 338 o ou H ocz 2 34 020 TAG CRIMPED LEADS SPECIAL ORDER ONLY TABLE 3 LENGTH H1 378 397 421 421 437 457 457 MARKING CODE 7 TABLE 4 CAPACITANCE MFDS WO...
Page 71: ...am plifiers because less RF voltage or current is needed in such systems to cause interference With properly designed audio equipment particularly that in tended for use by radio broad casters the inc...
Page 72: ...oms may also become in volved even to the extent of in cluding those of a completely separate carrier from a nother source No matter how complex the symptoms however there are two factors common to al...
Page 73: ...ch could add rather than cure RFI The pre ceding given values can be extrapo lated to other impedance levels simply by following the reciprocal relationship if the audio line im pedance is higher the...
Page 74: ...odulated it is likely that partial or full detection would take place resulting in audible recognition of the AM component along with normal program A sufficiently high level of RF however could com p...
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