B77 MkI/MkII Service InstructionsSafety Information

1 - GeneralTape Transport ControlsMonitor Panel/Repro ControlsRecord ControlsConnector Panel

2 - SpecificationsDimensions

3 - Dismantling3.1 - Case3.2 - Front Panel3.3 - Audio Control Section3.4 - Control Section Front Panel3.5 - Head Block3.6 - Brakes3.7 - Spooling Motor Right3.8 - Spooling Motor Left3.9 - Capstan Motor3.10 - Tape Counter3.11 - Pinch Roller Solenoid and Arm3.12 - Tape Lifter3.13 - Audio PCBs3.14 - Tape Transport Ctrl PCB3.15 - Speed Ctrl PCB3.16 - Power Transformer Unit3.17 - Audio Connector Panel3.18 - Tape Tension Arm3.19 - Audio Interconnect PCB3.20 - Meter Unit3.21 - Reel Size Switch3.22 - Varispeed Unit3.23 - Reassembly

4 - Tape Transport4.1 - Head Block4.1.1 - Tape Guides4.1.2 - Head Mounting

4.2 - Brakes4.2.1 - Braking Torque

4.3 - Pinch Roller4.3.1 - Pinch Roller Force4.3.2 - Pinch Roller Adjustment

4.4 - Capstan Motor4.4.1 - Capstan Shaft/Thrust Bearing

4.5 - Spooling Motors, Bearing Replacement4.6 - Lubrication

5 - Electronics5.1 - General5.2 - Audio Interconnect PCB5.3 - Input Amp5.4 - Record Amp5.5 - Oscillator5.6 - Repro Amp5.7 - Monitor Amp5.8 - Power Supply5.9 - Tape Transport CtrlNew Version 1.177.317

5.10 - Move Sensor5.11 - Speed Control5.12 - Varispeed5.13 - Tape Tension Switch MkII

6 - Electrical Adjustments6.1 - Test Equipment6.2 - Supply Voltage Check6.3 - Tape Transport6.3.1 - Functional Check6.3.2 - Tacho Head6.3.3 - Tape Speed6.3.4 - Tape End Swtich

6.4 - Audio Adjustments 6.4.1 - Calibration Tapes6.4.2 - Demagnetizing6.4.3 - Input Amp Gain6.4.4 - Mixer Test6.4.5 - Meter Calibration6.4.6 - Overload Indicators6.4.7 - Frequency Response "Before Tape"6.4.8 - Repro Head Azimuth, Coarse6.4.9 - Repro Head Azimuth, Fine6.4.10 - Reference Level from Calibration Tape6.4.11 - Repro Frequency Response6.4.12 - Oscillator Frequency, RF Voltages6.4.13 - Bias Trap6.4.14 - Record Head Azimuth, Coarse6.4.15 - Record Head Azimuth, Fine6.4.16 - Bias6.4.17 - Record Level6.4.18 - Record EQ6.4.19 - Overall Frequency Response

6.5 - Various Performance Data6.5.1 - Distortion Via Tape6.5.2 - S/N Ratio6.5.3 - Erase Efficiency6.5.4 - Crosstalk Mono6.5.5 - Crosstalk Stereo6.5.6 - Measurements "Before Tape"6.5.7 - W&F

7 - DiagramsPower Supply/Tape Drive Ctrl Block DiagramPower Supply 1.177.310.00Power Supply 1.177.311.00Power Supply 1.177.312.00Tape Drive Ctrl 1.177.315.00Substitution Logic PCB 1.177.316.00Tape Drive Ctrl MkI 1.177.317.00Tape Drive Ctrl MkII 1.177.317.81Tape Tension Switch 1.177.135.00/.136.00/.137.00Tape Move Sensor 1.177.320.00Tape Move Sensor 1.177.321.00Capstan Speed Ctrl MkI 1.177.325.00/.326.00/.327.00Capstan Speed Ctrl MkII 1.177.325.81/.326.81/.327.81Capstan Speed Ctrl MkII 1.177.325.82/.326.82/.327.82Varispeed Ctrl 1.177.330.00External Varispeed Ctrl 1.228.045.00Varispeed Ctrl PCB 1.128.048.00

Remote Ctrl Unit / Command Switches 1.128.040.00Remote Ctrl PCB 1.128.041.00

Audio Block DiagramAudio Interconnect 1.177.210.81Input Amp 1.177.220.00Input Amp 1.177.221.00Input Amp 1.177.221.81Record Amp (NAB 3 3/4 - 7 1/2 ips) 1.177.230.81Muting Circuit 1.177.215.00

Record Amp (NAB 7 1/2 - 15 ips) 1.177.232.81Muting Circuit 1.177.215.00

Record Amp (NAB 7 1/2 - 15 ips) 1.177.232.82Muting Circuit 1.177.215.00

Record Amp (IEC 7 1/2 - 15 ips) 1.177.233.81Muting Circuit 1.177.215.00

Record Amp (NAB 1 7/8 - 3 3/4 ips) 1.177.237.81Muting Circuit 1.177.215.00

Record Amp (NAB 15/16 - 1 7/8 ips) 1.177.238.81Muting Circuit 1.177.215.00

Oscillator 4-Track 1.177.240.00Oscillator 2-Track 1.177.242.00/.243.00Repro Amp (NAB 3 3/4 - 7 1/2 ips) 1.177.250.81Repro Amp (NAB 7 1/2 - 15 ips) 1.177.252.81Repro Amp (IEC 7 1/2 - 15 ips) 1.177.253.81Repro Amp (NAB 1 7/8 - 3 3/4 ips) 1.177.257.81Repro Amp (NAB 15/16 - 1 7/8 ips) 1.177.258.00Monitor Amp 1.177.260.00 Monitor Amp 1.177.260.81Slide Control Installation InstructionsFH (Free Head)DIA (Slide Synchro)DHA (Dissolve Head Amp)

Slide Synchronizer 1.177.270.00Dissolve Head Amp 1.177.282.00 (IF Simda ED 3000P)

8 - Spare PartsSpooling MotorCapstan MotorTape DrivePushbutton UnitBrake SystemTape Head AssyOperating Section

9 - Special Versions9.1 - B77 with Slide Sync Electronics9.1.1 - General

9.2 - B77 HS9.2.1 - General9.2.2 - Performance Data