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Страница 1: ...www SteamPoweredRadio Com INSTRUCTION MANUAL MODEL 375 TAPE RECORDING ELECTRONICS ...
Страница 2: ...www SteamPoweredRadio Com INSTRUCTION MANUAL MODEL 375 TAPE RECORDING ELECTRONICS 503 B VANDELL WAY CAM PBELL CA 95008 408 374 8300 ...
Страница 3: ...eamPoweredRadio Com TABLE OF CONTENTS SECTION 1 0 2 0 3 o 4 0 GENERAL INFORMATION INSTALLATION AND USE OPERATION AND FUNCTIONAL DESCRIPTION ALIGNMENT AND MAINTENANCE PARTS LIST SCHEMATICS PAGE 2 7 9 17 23 28 ...
Страница 4: ...hen no specification is made the unit is suppl ied with cabl ing for Ampex 350 351 series machines Among t he features incorporated are Cal ibrated positions on Record and Reproduce gain controls Provision for remote switching of all monitor and equalization functions and sol id state switching to eliminate contact noise problems 3 speed equalization to accommodate any combination of NAB and IEC c...
Страница 5: ...n situation A third group con tains those specifications which are not application oriented 1 1 1 Specifications derived using 3M 206 tape and a Taber full track replacement head assembly on an Ampex 351 transport Frequency Response in Hz 15 ips 7 5 i ps 3 75 ips 2dB 2d8 3dB 20 20k 20 15k 20 8k Signal to Noise Ratio in dB referred to a peak record level 6dB above 200nW m or approx 3dB below 3 THO ...
Страница 6: ...l track width format typical of multi track appli cations Frequency Response in Hz 30 ips 2dB 60 22k SYNC reproduce 15 i ps 2dB 30 22k response essen tially identical 7 5 i ps 2dB 20 16k to normal overall Signal to Noise Ratio in dB referred to approx 640nW m or 3 THO 20Hz 20kHz 30 ips 15 i ps 7 5 i ps Erase Bias Frequency 250kHz Erasure OVERALL u wtd wtd 71 78 67 77 67 76 SYNC u wtd wtd 71 80 67 ...
Страница 7: ...TER and LOW when transport provides closure Accom modates NAB IEC or mixed characteristics for 3 75 through 30 i ps operation Amplifier Oistor ion Record Input Outputs 1 THO at Op Level 25 THO 25d8 above Op Level Reproduce 1 THO at Op Level 5 THO at 24dBm Line Output clipping level 25dBm Sensitivity 20 to 8d8m 8 to 8d8m with 01 option input transformer Impedance lOK bridging Line Output feeds 600 ...
Страница 8: ...O LEVEL with pre set CAL position MONITOR selects between INPUT REPRO and SYNC 03 versions SAFE READY RECORD EQUALIZATION manual selection of HIGH INTER or LOW POWER Power Requirement 105 130 VAC _2_ 39 _ay l_ _ 50 60Hz 3A plus transport Size and Shipping Weight 3 X 1911 X 10 15 1bs 6 ...
Страница 9: ...__iate_ interconnect cabling 2 4 Unless supplied otherwise to special order units intended for mono or stereo installations are delivered properly aligned for use with 3M 206 tape at an operating level of 200nW m with Ampex 351 type heads 1 5mHy erase 5 lOmHy record and lHy reproduce and lOOkHz bias Units for multi track use normally operate with lower inductance heads 0 5mHy erase 4 5mHy record a...
Страница 10: ... the 375 input 2 8 No provision for meter indication of bias or erase current is made as the inherent stability of the circuitry is greater than that of the heads and meter at bias frequencies 2 9 When two or more 375 1 s are employed in dual or multi track ap plications the interconnecting cabling supplied delivers AC power to all units and to the transport if it derives power from the elect roni...
Страница 11: ...sferred to the rear panel REMOTE connector On versions with the 03 option mon itor is automatically switched from SYNC to INPUT when entering the record mode 3 1 3 The alternate action SAFE READY switch when depressed per mits the 375 to enter the record mode when the transport is in record11 When this button is out the 375 will not enter the record mode thereby preventing accidental erasure of a ...
Страница 12: ...iately wired by depressing an EQUALIZATION utton slightly so that all three buttons are 11 out11 3 1 6 The alternate action POWER switch controls AC power to the 375 and to the transport if it is powered by the electronics 3 1 7 The PHONES jack is connected ahead of the output transformer through a 470 ohm resistor It is suitable for headphone monitoring or as an unbalanced uncalibrated line outpu...
Страница 13: ...r input stage Q3 serving primarily as an emitter follower buffer DC feedback is maintained through R19 and Rll bypassed at audio frequencies by C2 AC feedback is routed through an appropriate equalization network by FET switches Q4 Q5 or Q6 A secondary function of Q3 is to provide a phase inverted reproduce signal at the collector for the repro duce phase compensation circuit This signal coupled t...
Страница 14: ... an effective open circuit between the source and drain When the gate is brought to ground potential either by the front panel MONITOR switch or through the REMOTE connector the source drai n resistance drops passing the selec ed signal Transistor Q29 and associated circuitry is part of the SYNC reproduce option 03 version only switching the line amplifier from SYNC to INPUT monitor when the 375 e...
Страница 15: ...if ier through RECORD CAL control R7 for__ _ source monitoring C4 imparts a 6dB octave rising characteristic to the imput signal as required for recording pre emphasis Depending upon the tape speed and equalization characterisitc used however only a rise at very high frequencies or no increase at all may be required C7 connec ted in the feedback path of IC2 therefore provides a complementary falli...
Страница 16: ...nd to the input of the SYNC amplifier for SYNC re produce 03 version only A bias trap composed of L2 C22 C24 and L3 C23 keeps bias from disturbing the head driver stage or overloading the SYNC amplifier FET switch Ql0 opens the input to IC4 except when the 375 is in the record mode 3 2 7 Erase Bias Amplifier The bias signal generated on the Power Supply PC assembly is raised to the required power ...
Страница 17: ...ite chain of events occurs 11 Punch i nII and II Punch outII time is symmetrical at about 100 milliseconds 3 2 9 Power Supply Schematic 129200 Triac Yl operates in conjunction with the front panel POWER switch to control primary AC power to the 375 and associated tape transport if deriving power from the unit This saves the switch contacts from heavy surge currents and inductive loads The chassis ...
Страница 18: ...switch or a transport speed switch closure Transistor QB normally off disables the reproduce and SYNC on 03 versions phase compensation network except at the one speed for which the network is optimized and for which a strap is connected see sec tion 4 2 2 Similarly the record amplifier pre emphasis characteristic includes a low frequency boost as required for NAB equalization which can be defeate...
Страница 19: ...producing the highest frequency on the tape adjust reproduce head azimuth for maximum output 4 1 2 4 If the resonance of the reproduce head with its cable is near the top of the passband as is usually the case for best signal to noise performance a peak in response will be ob served at the highest frequencies RI on the Reproduce Amp lifier card is provided to damp this resonance To determine wheth...
Страница 20: ...o operate into a 8dBm line remove the jumper across the 4 7K resistor near the output connector before making this adjustment 4 1 3 4 1 4 SYNC REPRODUCE 03 version only The SYNC reproduce function on 375 s so equipped is aligned in the same manner as the normal reproduce section described in 4 1 2 1 through 4 1 2 7 Playback is from the record head in this case and there is no front panel level adj...
Страница 21: ... manufacturer s recommendation for best performance 4 1 5 Depress the REPRO monitor button connect an audio oscillator to the INPUT connector and thread transport with a good sample of the type of tape to be used subsequently Place machine in record mode at 15 ips and adjust input to lkHz at about oper ating level adjust R13 BIAS control for maximum reproduced signal Use 500Hz at 7 ips on units wh...
Страница 22: ...e 4 1 5 5 Set equalization for lower speeds using R34 and R36 for INTER and LOW speeds respectively The input level should be re duced by lOdB for alignment of 7 ips and lower speeds 4 1 5 6 Switch front panel RECORD GAIN and REPRO LEVEL controls fully ccw to CAL position With input of normal line level and of the same frequency as the reference tone on the alignment tape used set Rl on Record PCB...
Страница 23: ...ro duced from the tape 4 2 1 3 An alternate method of adjustment requires only a typical studio program equalizer which can be peaked at 3kHz and give at least 15dB rejection at lkHz With this method the out put of the 375 is routed through the equalizer to the monitor speaker system and R39 adjusted for minimum perceived dis tortion 4 2 2 Phase Compensation 4 2 2 1 The 375 is equipped with a phas...
Страница 24: ...s illuminated by two long life 388 lamps which are considerably under voltaged In the event it eventually becomes necessary to replace one remove the top cover and remove the 3 1611 hex threaded spacer retaining the socket of the burned out lamp All illuminated switch buttons Squeeze the button from top and bottom and pull straight off The 387 lamp can be re moved carefully with a pair of long nos...
Страница 25: ... 2 11500 DESCRIPTION REPRODUCE PCB SCHEMATIC 129000 Capacitor 25uF 25V l00uF 3V lOOpF o OluF 100v 680pF lOpF 5uF 25V 120pF 62pF Diode Silicon 1N4009 Integrated Cct Type 748 C Transistor SE4010 2N3645 MPFlll 2N3567 Resistor adjustable 20K 10K It 2meg 100K Transformer head matching MFG sprague Elmenco Sprague Elmenco Sprague_ Elmenco FSC GE Signe tics FSC NSC NSC Motor NSC FSC Spectrol Beyer MANUFAC...
Страница 26: ... DTSAl 2002 225M C23 00 0834 2700pF Elmenco DM19 272J 01 0828 750pF tt DM19 751J Cl6 00 0825 1800pF tt DM19 182J 01 0821 820pF DM19 821J Cl7 28 0901 5uF 25V Sprague TE1202 Cl9 26 0867 O luF 100V 225Pl0491 C20 0810 lOOpF Elmenco DM15 101J C22 00 0829 3000pF DM19 302J 01 0828 750pF DM19 751J C24 00 0829 l000pF DM19 102J 01 0828 470pF DM19 471J CRl 6 1100 Diode Silicon 1N4009 FSC GE ICl 5 1300 Integr...
Страница 27: ...lll 2N3567 Resistor adjustable lOK It 2K It lK ti 20K ti I I SOK Transformer Bias Ampl ifier POWER SUPPLY PCB ASSY SCHEMArrIC 129200 Optical coupler Capacitor ti II II 500uF 50V 2 2uF 20V o OOluF 100v 300pF O 0039uF 100V o 001SuF 100v 2700pF 750pF O luF 100V MANUFACTURE MFG PART NUMBE FSC NSC II RCA RCA NSC NSC Mototl FSC NSC Spectrol I 43P 103 Helipot 91AR2K it 91AR1K Spectrol 43P 203 ti 43P 503 ...
Страница 28: ...ier 1N4005 Silicon 1N40 09 Integrated Cct Type 723 C Inductor lmHy 560uHy Transistor 2N5294 2N3567 2N3645 Resistor adjustable lK 200K Silicon Controll ed Rectifier C103B Triac T2500B CHASSIS MOUNTED ELECTRONIC COMPONENTS Capacitor O OluF 600V Fuse 3A A Indicator Lamp Type 387 Potentiometer 100K w SPST Switch MFG ITT FSC GE NSC T l dyn Delevan RCA FSC NSC Helipot GE RCA Sprague MANUFACTORE PART NOM...
Страница 29: ...818 It EQUALIZATION POWER 1817 It LINEARITY 1817 It LINE TERM I 1502 Transformer optional input 1503 shielq for input transformer UTC 1109000 Transformer output 130100 It power 2800 Meter VU with illumination kit MFG Swi tchcraf Cont Wirt ls U UTC Modutec MANUFACTURER PART NUMBER 67012 series GF 323 G 02 70 0 37 f zr0 17 Z 72 2BA AVU 000 AB KW BA1 ...
Страница 30: ... l OL Q R PR O RI EAi Iii wolO l RIO I k Tc 1 SC 4010 NW lllZ t l 2l0 1t t_ire I i R c 110 RlPROOOCC CQUN 1LAT10N R OK R13 i r r llo o L HI SPO AAII A L 11 rv __ QS I tlO k RZ1 N I no R23 ZIOk _J RIA UCHt I I I 6 RI PROl O t I I WITT I I I 9 20V 7 c 6eO Ql L _ AA __ R PRO P O l P s I It V R1 J il k R 2 r RcPROIJU E L AM US A IHSTALt 0 OPTION Rq4 M1t l F I I I _ ___ __ t 1 OJ I J O 12 G OVNO IQ REP...
Страница 31: ... RIO 1 M R 2 IOk QUAl ZATION HI PO INT 3 Z 4 8 A C Rll W k r HI WO IPrr iO LO IPO RWlRO El JALllATIOH Rn R IO Ea llNlAAITV D FUT r J J Th0lt l 24 f DR ALU I I I I WIit AMP IIIP fr l V l U 1 RlUlRO EAi l i _ L _ Z _ L3 I Tz j D f i 10 5 I I Ii I u f j I I I I I L R u E IIA t 11tAO I IF OA VAU 1 C l5 2 l Cl l tLIX aC OVT ii II L _ j c t USf D CIS LI Cl4 U IJSV QII IH 45 R51 IOk R 52 IOk 0 R5l R5 l S...
Страница 32: ...O l i l 4 1 5 0 Rl O 13 CRl4 I IN 4005 t T 6 8 CR CRl 2 u Powt A OHOOS ZOV 11 ti 3 K l 41 TR ANSMRME R I ll41 5 L E1 RS J r r s c v1 CR I NOTES U N t TU1 R Wl E Jl i C f1 0 i J 1xEO R E 1 TOA W 1 I01 VAlU IN l IM l CAPA tTAN E VAI UE IH MKRorA t J 0 1O0i i A RE P N nQa 4 R 12 1 t lo Y i W OR IIOVOC l AN PORT tG IC to k 4 W roAl VD TRAN P oRT lC lt c co 12 400 11 tl 00 3 9 z1oorr IOOW U tl 940 l Si...
Страница 33: ...AS IN BIO OUT GAOUNO n w y 0 _ J 10 POWE I i i g 2 I R6 NOTES I tRRc OTl W U SPHIFIEO 5 1 or 0 S D l Ft C 0 RE 5i TOR W liOl I VALUE IN OHM P ONES JC _ 1 1 1 JVV 470 2 R V 1 1 ONL WITH OP flONII L INPUT T R W JORME R n OA HEt LIN co NU llON wME No T V O 3 A MOVC JUMH R AC RO R4 roR e a LINE CALIBAA tlQN RE CORO I ttO 1 JUN 75 l lNOVONICS CHfCtr 10 IJBW 1 1 JUL 75 to ovirol I _ _ l6tilll _ alOG TIT...
Страница 34: ...he purchaser to return equipment for warranty service to the dealer from whom it was originally purchased unless prior arrangement is made with the dealer to inspect or repair at the user s location This warranty is subject to the following conditions 1 Warranty card supplied with the equipment must be completed and returned to the factory within 10 days of purchase 2 Warranty is void if unauthori...
