Ampex-MR-70-OP-Maintenance.1965.01 电路图 维修手册.pdf

40108-1, MR-70 Recorder/Reproducer Publication No. 4890145-10 January 1965 AMPEX CORPORATION 401 Broadway Redwood City, California Printed in U.S.A. LIST OF EFFECTIVE PAGES PAGE ISSUE IN PAGE ISSUE IN PAGE ISSUE IN PAGE ISSUE IN NUMBER EFFECT NUMBER EFFECT NUMBER EFFECT NUMBER EFFECT 401084 A 1/65 401203 A 1/65 401040 A 1/65 401083 A 1/65 401085 A 1/65 401204 A 1/65 401041 A 1/65 401086 A 1/65 401205 A 1/65 401042 A 1/65 401087 A 1/65 401206 A 1/65 401043 A 1/65 400901-1 A 6/64 401207 A 1/65 401044 A 1/65 401182 A 1/65 401208 A 1/65 401045 A 1/65 401183 A 1/65 401209 A 1/65 401046 A 1/65 401184 A 1/65 401210 A 1/65 401047 A 1/65 401185 A 1/65 401211 A 1/65 401048 A 1/65 401186 A 1/65 401212 A 1/65 401049 A 1/65 400901-2 A 6/64 401313 A 1/65 401050 A 1/65 400922 A 1/65 401214 A 1/65 401051 A 1/65 400924 A 1/65 401215 A 1/65 401052 A 1/65 400926 A 1/65 400902-2 A 6/64 401053 A 1/65 400928 A 1/65 401216 A 1/65 401054 A 1/65 401006 A 1/65 401217 A 1/65 401055 A 1/65 401007 A 1/65 400904-3 A 6/64 401056 A 1/65 401008 A 1/65 400881 A 8/64 401057 A 1/65 400901-3 A 6/64 401015 A 1/ 65 401058 A 1/65 401009 A 1/65 401016 A 1/65 401059 A 1/65 401010 A 1/65 401017 A 1/65 401060 A 1/65 401011 A 1/65 401018 A 1/65 401061 A 1/65 401012 A 1/65 401019 A 1/65 401062 A 1/65 401013 A 1/65 401020 A 1/65 401063 A 1/65 401014 A 1/65 401021 A 1/65 401064 A 1/65 400904-4 A 6/64 401022 A 1/65 401065 A 1/65 401187 A 1/65 401023 A 1/65 401066 A 1/65 401188 A 1/65 401024 A 1/65 401067 A 1/65 401089 A 1/65 401025 A 1/65 401068 A 1/65 401190 A 1/65 401026 A 1/65 401069 A 1/65 401191 A 1/65 401027 A 1/65 401070 A 1/65 401192 A 1/65 401028 A 1/65 401071 A 1/65 401193 A 1/65 401029 A 1/65 401072 A 1/65 401194 A 1/65 401030 A 1/65 401073 A 1/65 401195 A 1/65 401031 A 1/65 401074 A 1/65 401196 A 1/65 401032 A 1/65 401075 A 1/65 401197 A 1/65 401033 A 1/65 401076 A 1/65 401198 A 1/65 401034 A 1/65 401077 A 1/65 401199 A 1/65 401035 A 1/65 401078 A 1/65 401200 A 1/65 401036 A 1/65 401079 A 1/65 401201 A 1/65 401037 A 1/65 401080 A 1/65 400904-1 A 6/64 401038 A 1/65 401081 A 1/65 401202 A 1/65 401039 A 1/65 401082 A 1/65 A 401085A TABLE OF CONTENTS Section 1 1.1 1. 2 1. 3 1. 4 Section 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 Section 3 3.1 3. 2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Section 4 4.1 4.2 4. 3 Section 5 5.1 5.2 5.3 5.4 5.5 Section 6 6.1 6.2 6.3 Section 7 ,1010. DESCRIPTION General . . . . Tape Transport . . Electronic Assembly . . . . Specifications . . . . . . . INSTALLATION Unpacking . . . . . Preliminary to Installation . . . . . Mounting . . . . . Interconnecting Components . . Connecting Signal Lines . . . . Connecting Power . . Location of Plug-In Units . . Strapping for 115 or 230 Volt Power Source . . . . . . . . . Output Line Selection . . Connecting Accessory Equipment or Installing Jumper Plugs . . . . . Adjusting Reel Turntable Height . . OPERATING INSTRUCTIONS General Instructions . . Controls and Indicators . . Tape Threading . . . . Recording . . Reproducing (Playback) . . Use of Fastwinding Mode . . Editing . , . . Operating from Optional Remote Control Unit . . . . Recording Sound-On-Sound . . . . . . TRANSPORT MAINTENANCE Routine Maintenance . . . Corrective Maintenance . . Principles of Operation . . . . . . ELECTRONIC MAINTENANCE General . . . . . . Checkout and Adjustment Using Standard Tape . . . Checkout and Adjustment Without Standard Tape . . Low Frequency Head Compensation . . . . Principles of Operation . . HEAD ASSEMBLY General . . . Maintenance of Head Assemblies . . Track Widths . . PARTS LISTS AND DRAWINGS Page 1-1 1-1 1- 2 1-2 2-1 2-2 2-2 2-3 2-3 2-4 2-4 2-5 2-6 2-6 2-7 3-1 3-2 3-3 3-3 3-4 3-4 3-5 3-5 3-6 4-1 4-5 4-8 5-1 5-1 5-6 5-7 5-8 6-1 6-1 6-2 LIST OF ILLUSTRATIONS 11 Figure 1-1 1-2 2-1 2-2 3-1 3-2 3-3 4-1 4-2 4-3 4-4 4-5 4-6 4-7 5-1 5-2 5-3 5-4 5-5 5-6 5-7 7-1 7-2 7-3 7-4 7-5 7-6 7-7 7-8 7-9 7-10 7-11 7-12 7-13 MR-70 in Console . . Tape Transport . . Console Mounted Equipment . . Suggested Electronic Remote Control . . Tape Transport Controls . . Electronic Assembly Controls . . Tape )breading Path . . Special Tool for Checkout . . Checking Holdback Tension . . . Timing Adjustment-Transducer . . Brake and Idler Adjusbnent . . Tape Speed Adjustment . . Fusing Diagram . . Relay Operating Chart . . Filter for Noise Measurements . . Equivalent Circuit-Head and Input . . Head Output . . Flattening Head Output . . Result of Moving Head Resonance . . Final Response . . Head Gap Compensation . . Schematic Diagram-Transport, Power Supply Schematic Diagram-Transport, Motor Control Schematic Diagram-Transport, Logic Section Schematic Diagram-Electronics, Power Supply Schematic Diagram-Electronics, Record Section Schematic Diagram-Electronics, Reproduce Section Schematic Diagram-Master Bias Oscillator Schematic Diagram-Bias Amplifier Module Schematic Diagram-Output Amplifier Module Schematic Diagram-Remote Control, Transport Schematic Diagram-Sel-Sync Amplifier Module Schematic Diagram-Microphone Preamplifier, 40 db Schematic Diagram-Microphone Preamplifier, 60 db Page 1-1 1-2 2-1 2-7 3-2 3-2 3-3 4-1 4-2 4-5 4-7 4-8 4-8 4-9 5-5 5-10 5-10 5-10 5-11 5-11 5-12 010ll7A 1.1 GENERAL The Ampex Model MR-70 Mag-netic Tape Recorder/Reproducer is a high quality equipment designed for use in the professional recording field. The recorder is available mounted in a console (see Fig. 1-1) or unmounted for installation in a stand- ard 19-inch rack. While the MR-70 is compatible with other Ampex recorders, major improvements have been made in such areas as signal-to-noise, distortion, and flutter. The use of high grade Nuvistors in con- junction with rugged construction techniques assures maximum reliability and performance. The equipment consists basically of a tape transport assembly and electronic assemblies as required (one for each channel). Accessory plug-in items are available from Ampex that will add to the versatility of the machine. 1.2 TAPE TRANSPORT Tape transports (see Fig. 1-2) are avail- able for 1/4-inch, 1/2-inch, and 1-inch magnetic tape. Head assemblies for 1/4-inch tape may be ordered with 1 or 2 tracks; for 1/2-inch tape with 2, 3, or 4 tracks; and for 1-inch tape with 3, 4, 6, or 8 tracks. Two tape speeds are provided on all transports-either 7-1/2 and 15 ips (inches per second) or 15 and 30 ips. 401182A Section 1 DESCRIPTION Fig. 1-1 MR-70 m Console 1-1 t i:- . . - .-. 9-0- - ; Fig. 1-2 T.1pe Transport Indirect drive to the capstan is provided by a hysteresis-synchronous motor. Tape speed is adjustable over a small range by varying the force between the motor and the capstan flywheel. A constant tension holdback system employs a transducer which senses the position of the tape as it leaves the supply reel and varies the holdback torque of the supply motor accordingly. Another feature is the viscous damping of the reel idler flywheel to further improve the flutter and wow characteristics. A heavy ca.sting, which serves as a mounting base for all components, assures that critical alignment of those components is accurate and long-la.sting. Pushbutton control of tape motion, power, and speed selection is provided. 1.4 1. 4.1 1-2 SPECIFICATIONS Tape Transport Tape Width and Channel Configuration Tape Speeds Maximum Reel Size Flutter and Wow Measured according to ASA Z57 . 1- 1954 measuring all components from 0. 5 cps to 250 cps. Start Time A master bias and erase oscillator, mounted on the tape transport, feeds a bias amp- lifier in ea.ch electronic assembly which in turn routes the 150 kc sig11a.l to the record and erase heads. 1.3 ELECTRONIC ASSEMBLY Each electronic assembly provides the record and reproduce facility for one channel. Modular construction is employed wherever feasible, with the record driver amplifier, re- produce output amplifier, and bias amplifier as- sembled as plug-in units. Several accessory items-such as a Sel-Sync*amplifier, input trans- formers, etc. -are also complete modules which simply plug into provided receptacles. The output may be strapped to feed either a 600 ohm or 150 ohm line at a level of either +8 vu or +4 vu. Record and reproduce level controls can be locked in position to prevent acci- dental change of settings, and the accidental erasure of a recorded tape can be prevented by placing a record selector switch in the SAFE position. Nuvistor circuitry provides better re- liability and performance than are available with conventional vacuum tubes or germanium tran- sistors. Stable operation is achieved by conserva- tive design, using high feedback, and employing high quality components. * TM, Ampex Corp. 1/4-inch-l or 2 channels 1/2-inch-2, 3, or 4 channels 1-inch-3, 4, 6, or 8 channels 2 speeds- 7-1/2 and 15 ips or 15 and 30 ips 11-1/ 2-inch CCffi (CCffi Adaptors available) 7 ips less than 0. 08% rms 15 ips less than 0. 05% rms 30 ips less than 0. 05% rms Tape will be within :1:0. 2% of nominal speed in 0. 5 second. 401 tH: is in the stop mode and tape is properly threaded. Fastwinding slider: Determines the di- rection and speed of tape motion when the equipment is in fast mode. fast pushbutton: Places equipment in the fastwinding mode. Direction and speed of tape mo- tion is determined by the position of the fastwinding slider control. The FAST indicator, immediately above the pushbutton, is illuminated when the equip- ment is in the fast mode. The slider can be moved from a fast forward to a fast rewind position or vice versa; tape motion will slow to a stop and then reverse direction. flay pushbutton: Starts equipment in the playback mode. The PLAY indicator immediately above the pushbutton is illuminated when the equip- ment is in the play mode. 3-2 !;dit pushbutton: Places the equipment in the edit mode . The EDIT indicator immediately above the pushbutton is illuminated when the equip- ment is in this mode. The equipment can be placed in the stop-edit mode (where mechanical brakes are released, light hysteresis braking applied, the head gate closed, and reels may be manually turned) , the play-edit mode (where operation is similar to play- back but the takeup motor does not reel in tape- which spills off the right side of the transport) , or the fast-edit mode (where the head gate is closed and the recording can be monitored in the fastwind- ing modes). _gecord pushbutton: Starts equipment in the record mode. The RECORD indicator immediately above the pushbutton is illuminated in this mode . The RECORD SELECTOR switch(es) on the electron- ic assemblies must be in the READY TO RECORD position or this pushbutton will not lock in the re- cord mode. 3.2.2 Electronic Assembly (see Figure 3-2) OUTPUT SELECTOR: This is a rotary control with three positions-REMOTE SELECT, REPRODUCE, and INPUT. In the remote select position, selection of the other two functions is transferred to auxiliary switching which can be in- stalled with the optional remote control. In the re- produce position, the signal recorded on the tape is delivered to the output circuit for monitoring; it can be placed in this position while recording to monitor the record function, and must be in this position for playback. In the input position, the in- put signal can be monitored while recording, or re- cord level can be set before starting tape in motion. While recording, the switch can be moved back and forth between reproduce and input to provide an A- B comparison of the actual program and the record- ing. Fig. 3-2. Electronic Assembly Controls 4010 I0A - - VU meter: Indicates level of signal, bias, or erase, as selected by the meter switch. METER switch: This is a three position switch which selects the signal to the v-u meter. Selections are for OUTPUT, BIAS, and ERASE. During operation this switch is placed in the output position where the meter will indicate either re- cord or playback level (determined by the position of the OUTPUT SELECTOR switch). In the bias and erase positions, the meter will indicate bias or erase levels, normally checked and calibrated dur- ing maintenance procedures. RECORD SELECTOR: This is another three position switch, selecting SYNC REPRO, SAFE, or READY TO RECORD. The sync repro position is used when recording sound-on-sound, using the optional sync amplifier. In the safe posi- tion, the record mode is locked out on that channel. In the ready to record position the channel can be placed in the recor