Technical
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Camera SocketThe 14 Pin Camera socket is known as a Sony K-connector. Details of the pin connections are available online.Fault and repair guideNo E to E soundFor no sound from the tuner check the TBA120 FM demodulator ICNo Playback AudioSuspect the audio change-over relay on the AS-3 board.Problems setting clock or timerThe switches used on the clock and timer section are prone to failure. When they begin to stick they can cause all sorts of erroneous behaviour. The only reliable cure is to replace them.Machine stops intermittently in rewindCheck that the APS and or memory function is not switched on.VCR is sluggish in or fails to rewindInternally the C7 contains many drive belts which are used in the mechanics of tape transport. With age these belts become slack causing malfunctions and when this happens the whole lot should be replaced. In particular for the rewind function you will need to replace a tyre on the supply reel. A 'rewind' kit of replacement parts is available from many sources. The Sony part number is A 670634A.Strange behaviour of capstan or drum servoThe first thing to check is the tantalum capacitors in the servo circuit. Look for the 2.2 micro farad ones first.Sluggish threading and capstan problemsThe bottom bearing on the capstan motor is prone to wear and because this motor also drives the threading mechanism threading can become sluggish. When this happens you will hear a horrible squeaking noise! It is possible to strip down the motor and replace the bearing but an easier option is to replace the entire motor if you can find a replacement.Picture drops out in playbackThis can be caused by lack of CTL pulses from the Audio/Control head. One remedy is to modify the CTL amp circuit to give it more gain. Alternatively a worn head can be 'polished up' to prolong its life. |
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