Sony 1978
Betamax SL-C5

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SL-C5 rear connectors
SL-C5 rear connectors

Fault and repair guide

Tape transport is sluggish or fails to rewind

Internally the C5 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/drum servo

The first thing to check is the tantalum capacitors in the servo circuit. Look for the 2.2 micro farad ones first. It is also recommended to replace the light blue electrolytics on the servo board.

Sluggish threading and capstan problems

The 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.

Colour in picture search

Although the C5 did not support colour in picture search it is possible to obtain colour by removing the colour mute transistor!

Camera Socket

The 14 Pin Camera socket is known as a Sony K-connector. Details of the pin connections are available online.

Quick fault guide

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Blank raster and muted playback with own recordingsCheck the audio/control track head for contamination and wear if ok then check the control head replay amplifier for failure.
Intermittently crackling soundSuspect poor contacts in the audio switching relays.
Intermittently fast forwards in playbackSuspect failure of sensor IC BX3421
Loss of capstan servo lock with noise bars & wow on soundTry slight adjustment of the capstan free run speed
No/poor soundCheck the setting/condition of preset RV403
No drum rotationCheck diode Dl on the audio/servo board AS6 for short circuit, if fault persists check IC1 ICX1861 for failure.
No play or fast forwardCheck capacitors C2, C3 & C4 for failure
No sound in e-e mode or recordSuspect failure of the sound IF chip IC503 [TBA2OB]
Poor picture with horizontal blue lines down screenCheck the tape back tension and the positioning of the tape path guides before suspecting the heads of wear failure
Shuts down when play is initiated but LED remains litCheck the slack sensor lever and the reed switch
Major loss of sync in playbackReplace these light blue Sanyo caps on AS-6 servo board with tantalums, 25 WVDC or higher. Board is accessed via the underside of enclosure by removing cadmium-coloured screws at board perimeter and 2 in the middle.

C041 0.33 / 25V
C043 1.00 / 25V
C011 0.47 / 25V
C045 0.47 / 25V
C052 0.22 / 25V

thanks to steptoesyard on
Will not UnlaceCheck Q501 for open circuit on LS3 PCB
Not erasing previous chroma or soundMainly no sound records. Check and replace RL401 (Faulty).