Revox G36 Service Manual
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Revox G36 Service Manual

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  • Page 2: Table Of Contents

    Contents General Mechanical Description Mechanical checks and adjustments 2.1.1 Tape path 2.1.2 Brakes 2.1.3 Tape tension 2.1.4 Pinch roller 2.1.5 End of tape switch 2.1.6 Wow and flutter 2.1.7 Tape speed Routine maintenance 2.2.1 Cleaning 2.2.2 Lubrication 2.2.3 Servicing of solenoids 2.2.4 Servicing of push button assembly Removal of capstan assembly...

  • Page 3: General

    Genera The REVOX Series 36 has been constantly improved and kept up to date, since it was first introduced in 1956. However, the present G still bears the same basic layout and conception as did the original A recorder. Compared with the preceding models, the following major innovations have been...

  • Page 4: Mechanical Checks And Adjustments

    arm carries the shield for the playback-head and the tape-lift mechanism for the rewind function. The brakes are mechanical in nature but are electrically operated. This is achieved by the action of the brake solenoid which pulls the brakes off during all operating functions.

  • Page 5: Tape Path

    great care in tightening the turntable screws uniformly to prevent them from wobbling. For best results, they may have to be rotated by 120°. 2.1.1 Tape path The tape path level is determined by the left and right hand tape guides (3 in fig. 1) and by a small guide (4) positioned between the playback head and the capstan.

  • Page 7: Tape Tension

    It is important to check that the brake band (6) is running flat on the brake lining and not biting on the upper or lower edge. Adjust alignment of brake band by slightly pivoting it in the rivets if required. Correct tension for spring 7 is obtained when 160-220 grams applied as a tangent force to a 10 cm diam (spool and tape) causes the spool to move.

  • Page 8: Pinch Roller

    2.1.4 Pinch roller The pressure of the pinch roller can be measured by a gauge fixed to the pinch roller arm as close as possible to the spindle of the pinch roller (fig. 4). A constant tone tape should be played and the pinch roller withdrawn by the gauge until the note is heard to change.

  • Page 9: Wow And Flutter

    To de-energize the solenoid and to restore the nonconducting condition, the supply voltage has to be interrupted. Mechanical end-of-tape switch. This switch and its associate operating levers must be thoroughly clean to function correctly. On G-36 recorders up to serial number 36 500, the tape sensing lever operates a snap-action switch (SE schematic A) which is closed with tape tension applied.

  • Page 10: Tape Speed

    Should the replacement of a motor bearing become necessary, return the unit to the nearest REVOX Repair Station. On wind motors with ball bearings (Series I and II) it is advisable to replace the ball bearings...

  • Page 11: Servicing Of Solenoids

    2.2.4 Servicing of push button assembly Conventional switch cleaners are not recommended for the high current spring contacts used in the REVOX, and where cleaning is necessary, the contacts should be polished clean. The interlocking bars and push-button shafts may require occasional greasing with molybdenum grease.

  • Page 13: Electronic Description

    Access to the majority of the electronics of. the recorder can be obtained by removing the base of the recorder. The REVOX G-36 has two identical record- and replay- channels. The common bias and erase Oscillator can be switched onto either one or both channels, thus allowing stereophonic recordings, two-track sound with sound and monophonic recordings.

  • Page 14: Magnetising

    schematic G-36) provided that the residual RF-signal is at least 35 db below peak record level (3 % distortion). A wow- and flutter meter may be required in rare instances only. 3.1.2 De-magnetising From time to time the ferrous parts in contact with the tape may become magnetised. When this occurs, especially with head magnetisation, an increase in background noise will be evident and in serious instances, partial erasure of the tape may come about.
  • Page 15 Good high frequency response is possible only when the gaps of the record- and playback heads are parallel to each other. Where recordings are to be exchanged for replaying on other machines, it is furthermore essential that the head gaps are accurately aligned to an angle of 90°...

  • Page 16: Playback Amplifier

    “dead channel” cross-talk. Where a four track recorder is under examination, it is advisable to obtain the REVOX four track alignment tape. Relevant instructions are included with the tape. 3.1.4 Playback amplifier Before any tests are made on the playback section of the recorder, it is essential to ensure that the sound heads are scrupulously clean;...

  • Page 17: Bias Adjustment

    VTVM. This external filter will not be required on REVOX G-36 recorders already equipped with bias-traps. It must be observed, however, that the residual bias remains below the level specified under 3.1.1.

  • Page 18: Measurement Of Overall Frequency Response

    The generator signal level should then be reduced by 20 db and the output level noted. After changing the frequency to 10 kc/s, bias should be adjusted to an output identical to that at 1 kc/s. 3.1.6 Measurement of overall frequency response Before any attempt is made to verify the overall response, it is advisable to see that all tests described in the preceding paragraphs have been properly observed and that the settings arrived at have been left undisturbed.

  • Page 19: Vu-Meter Adjustment

    3.1.7 VU-Meter adjustment Peak record level is defined as the level at which the signal contains 3 % of third harmonic due to tape distortion. This should correspond to an output level approx. 3 db above the reference level of the calibration tape. Where a distortion analyser is available, the alignment procedure is as follows: Record a 1 kc/s signal via the radio input with the record level control wide open and adjust generator level until a distortion factor of 3 % can be measured on the cathode...

  • Page 20: Adjustment Of Head Shielding

    3.1.8 Adjustment of head shielding This may sometimes be necessary in order to keep the operating hum levels at a minimum. It should be noted also that since hum can be picked up by the electronics on the underside of the recorder, care must be taken to screen the base when the chassis is removed from its case, whether on the service bench for attention, or when built into a cabinet.

  • Page 21: Tuning The Bias Traps

    3.2 Tuning the bias traps The following procedure is suggested for tuning the filters L l/T 855 and L 2/T 855 (see schematic G 36, 6) on the output of the stages V 5. 1 and V 5.2 : The record circuits of both channels should be switched on by depressing the buttons “record”...

  • Page 22: Troubleshooting

    4 Troubleshooting 4.1 Mechanical troubleshooting Trouble Cause How to repair Capstan motor does Speed switch in mid-position Switch to 3 3/4 or 7 1/2 not run at either speed speed Speed switch defective Replace wafer Jamming motor Clean and lubricate bearings (2.2.2.) Jamming capstan bearing Replace capstan assembly...

  • Page 23: Electronic Troubleshooting

    Wow and flutter Damaged or dirty pinch roller, Replace pinch roller. pinch roller pressure Clean capstan and pinch insufficient, left side brake roller, adjust pinch roller maladjusted, jammed turntable arm (2.1.4.) adjust brake motor. (2.1.2.) clean and lubricate motor-bearings Fast rewind or forward Brake maladjusted Adjust brakes (2.1.2.) too slow...

  • Page 24: Technical Data

    5 Technical Data Tape Speed: 3 ¾ and 7 ½ ips 6/12 pole Hysteresis Synchronous capstan motor, direct drive Wow and flutter: ≤ ± 0.1%, at 7 ½ ips peak reading ≤ ± 0.15%, at 3 ¾ ips weighted (DIN 45507) Tape speed deviation: ≤...
  • Page 25 Case dimensions: 19 x 13 ½ x 12” Chassis dimensions: 21 ¾ x 15 ½ x 10 ¾” (with 10 ½” reels) Colour: grey All data are valid for the 2-track as well as for the 4-track recorder unless specified otherwise.

  • Page 26: Circuit Diagram

    6 Circuit Diagram...
  • Page 30 - 13 db which greatly eliminates the possibility of generating beat signals from ultra sonic frequencies. Where stereo broadcasts are to be recorded, use of the REVOX- multiplex filter will be essential, particularly when operating at the tape speed of 3 3/4...
  • Page 31 REVOX G 36 recorders not containing these modifications can easily be adapted to the new response characteristic by replacing and/or adding the above mentioned components.

  • Page 39: Spare Parts List - Issue

    7 SPARE PARTS LIST - ISSUE IV This Issue of the Spare Parts List has been augmented in all sections and exploded views are included for the more complicated sub-assemblies. The tabulations are divided into the following columns: INDEX Index numbers are identical with the tracer numbers shown in the drawings and photographs.
  • Page 40 Plastic Cover for Pressure Roller 7025 1.736.500-13 Plastic Head Cover (without Name Plate) 7026 21.02.3356 Machine Screw M 3x10, Oval Head 7028 43.02.0101 Revox Name Plate 7029 1.736.855 Plastic Head Cover (with Name Plate) 7027 1.736.500-04 Grey Plastic Knob (transparent) 7030 1.736.500-10...
  • Page 41 INDEX ORDER PART DESCRIPTION SERIES N° Push Button Assembly 1.736.550 Push Button Assembly Complete Colour 1035 7140 1.736.550 Push Button Assembly Complete Colour 6760 7141 20.21.7203 Self Tapping Screw (Push Button Mounting) 7142 1.736.578-02 Push Button Grey Colour 1035 7143 1.736.578-02 Push Button Grey Colour 6760 7144...
  • Page 42 1.736.150-05 Motor Wafer 7157 1.736.150-10 Motor Wafer 7158 1.736.150-06 Equalization Wafer 7159 1.736.170 Recording Channel Selector Complete 7160 1.736.170-03 Oscillator Wafer 7161 1.736.170-02 Amplifier Wafer 7162...
  • Page 43 INDEX ORDER PART DESCRIPTION SERIES N° Capstan Drive Assembly 1.736.125 Capstan Drive Assembly Without Head Support 50Hz 1.736.126 Capstan Drive Assembly Without Head Support 60Hz 1.736.120 Capstan Drive Assembly Without Head Support 7.5/15 ips 50 Hz 4/8 Pol 1.736.122 Capstan Drive Assembly Without Head Support 7.5/15 ips 50 Hz 6/12 Pol 22.01.8040 Hexagon Nut...
  • Page 44 INDEX ORDER PART DESCRIPTION SERIES N° Capstan Bearing Plate with Shaft 1.736.128 Capstan Bearing Plate Complete with Shaft 50 Hz 7082 1.736.129 Capstan Bearing Plate Complete with Shaft 60 Hz 7087 1.736.128-02 Capstan Shaft 50 Hz 7083 1.736.129-02 Capstan Shaft 60 Hz 7088 1.736.120-02...
  • Page 45 INDEX ORDER PART DESCRIPTION SERIES N° Head Support Block...
  • Page 46 1.736.227 Head Support Block Complete with 2-track Heads without pinch-roller arm 1.736.228 Head Support Block Complete with 4-track Heads without pinch-roller arm 1.736.229 Head Support Block Complete with 2-track Heads 7.5/15 ips 6/12 pol 1.736.226-01 Head Mounting Plate, bare 7076 1.736.226 Head Mounting Plate, Complete, without Heads 1.736.224...
  • Page 47 50.03.0210 Transistor AC 124 7065 50.03.0421 Transistor RT 9448 7066 1.736.237-01 Mounting Bracket 53.99.0114 Lamp Socket E – 10 7068 51.99.0108 Minature Lamp Osram 10 – 3664 (3.7V / 0.3A with 7067 Lens) 1.736.219 Tape Lift Lever OLD 7077 24.16.3032 Retaining Ring for above 1.736.220 Tape Lift Lever NEW...
  • Page 48 INDEX ORDER PART DESCRIPTION SERIES N° Brakes – Spooling Motors 1.736.794 Turntable with Shaft Section 7100 21.02.3355 Machine Screw Oval Head M 3x8 7104 1.736.794-01 Shaft Section, Upper 7101 1.736.794-02 Shaft Screw 7102 1.736.794-03 Reel Lock Spring 7103 1.736.360 Brake Drum Complete 7096 1.736.358 Brake Drum Complete...
  • Page 49 Brake Drum 1.736.502-17 Tubular Spacer Right 1.736.502-16 Tubular Spacer Left 21.01.0455 Machine Screw M 4x8 1.736.103-02 Mounting Bracket, Spooling Motor 7095 1.736.002-03 Spooling Motor 50 Hz 7093 1.736.103-01 Spooling Motor 50 Hz 7094 1.736.515-01 Spooling Motor 60 Hz 1.736.520 Motor Deck Complete 1.736.521 Motor Deck Complete 7.5 / 15 ips 1.736.378...
  • Page 51 INDEX ORDER PART DESCRIPTION SERIES N° Amplifier - Chassis 59.12.0103 Electrolyte Condensor 3 x 50 µF 350 V 7163 59.12.0106 Electrolyte Condensor 3 x 600 µF 35 V 7164 70.01.0131 Rectifier B 30 C 1000 / 600 Sealed 7165 70.01.0102 Rectifier B 250 C 100 7166 70.01.0161...
  • Page 52 1.736.880 Outer Shaft Extension Complete Monitor Selector 7208 1.736.400-03 Inner Shaft Extension, Long 7209 1.736.400-02 Inner Shaft Extension, Short 7211 1.736.770-02 Loudspeaker AD 3800 M 7193 1.736.770 Loudspeaker Complete with Baffle 1.736.501-04 Washer, Speaker Baffle 7194 20.21.7206 Self Tapping Screw 7195 22.01.8040 Hexagon Nut M 4...

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