Revox-A77-tape-sch2 维修电路原理图.pdf

REVOX A77 Is it quite useful to describe the REVOX A77? 25 years ago, each recording studio contained two or three of them; to make copies or to generate echoes or to delay the signal sent to the reverberations with plate or springs. Several accessories appeared progressively: plates and cores CCIR or NAB and a kit to use loops of magnetic tape It left then a model 38 and 19 cm/s CCIR, generalized in the studios and, of course, most interesting, there is a model with 4 tracks stereo (1/4 of track) and a model Dolby B; to avoid both! For our use, model 19-38 is the only interesting one. It is necessary to point out that the Revox A77 is a dual track and not a true stereo machine (the difference is in the precise width of each track and the distance between these tracks). It is the same, and its there that difficulties can arise, for the head alignment which is a dual track and not single track; a small central band must thus not be unobtrusive and undesirable deaf noises can appear at the time a band already has been recorded or magnetized by a continuous-current field. Lastly, do not miss the end of this page: if you are owner of an A77, you will find there, in pdf format, all the electronic diagrams necessary to its repair. DESIGN FEATURES General principle: mechanism with 3 motors, all electronically controlled Tape speeds: 19 cm/s (7 1/2 in/s) 9,5 cm/s (3 3/4 in/s) 0,2 % Wow and Flutter: 0,08 % 19 cm/s 0, 1 % 9,5 cm/s Drift: = 0,2% Diameter of the reels: maximum 26,5 cm ( 10 1/2 in ) Position of operation: Horizontal or vertical Amplifiers: equipped entirely with transistors with silicon structure double diffusion Response curve recording-reading: 30 Hz 20 kHz +2/-3 dB 50 Hz 15 kHz 1 , 5 dB 30 Hz 16 kHz +2/-3 dB 50 Hz 10 kHz 1,5 dB 19 cm/s 9,5 cm/s Harmonic distortion: (maximum level 1 kHz) = 2 % 19 cm/s = 58 dB 19 cm/s = 56 dB 9,5 cm/s Retreat of cross talk ( 1 kHz): = 60 dB, mono = 45 dB, stereo Oscillation frequency: 120 kHz, push-pull oscillator Inputs per channel: cinch and jack DIN 5 poles cinch Microphones commutable LO/HI LOW: 50 600 ohms 0,15 mV HIGH: 100 kohms 2,5 mV RADIO: 33 kohms 2,5 mV AUX: 1 Mohms 35 mV Outputs per channel: DIN 5 poles cinch jack OUTPUT max. 2,5 V / Ri 600 ohms RADIO max. 1,2 V / Ri 2,5 kohms PHONES ear-phones 200 to 600 ohms remote Control: all remotely controllable functions by impulses Amplifiers of loudspeakers: plug-in, delivered on request Power of exit: (load 8 ohms distortion = 1 %) musical power20 W ( 10 W per channel ) in sinusoidal mode16 W ( 8 W per channel) Output impedance: 4 to 16 ohms RadioFans.CN 收音机爱 好者资料库Built-in loudspeakers (model bag): 2 loudspeakers per channel (disconnected automatically at the time of the connection of external loudspeakers) Component: (with the amplifiers of loudspeakers) 54 transistors, 32 diodes, 4 rectifiers with silicon, 1 photo resistor, 4 relays Power supply: stabilized Tensions of the network: 110, 130, 150, 220, 240, 250 V-, 50 and 60 Hz Consumption: 70 W without the amplifiers of loudspeakers between 70 and 100 W with the amplifiers Fuses: 0,5 A for 220 to 250 V 1,O A for 110 to 150 V Weight: Approximately 15 kg RadioFans.CN 收音机爱 好者资料库