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Technics RS-B10 Very low meter reading on left channel playback. Also hum and noise. Operating tape selector switch caused left channel meter LEDs to flash full scale. Record / playback mode switch cleaned - unit OK.
Technics RS-631 Unit had intermittent playback on right channel. All switches cleaned to no effect. After much frustration fault traced to intermittent o/c lead on record / playback head.
Technics RS-671USD Unit destroys tapes. Pinch roller replaced - OK.
No F/FWD, R/W or play autostop. Resistor R225 220R/0.5W found burned. Also the brown solenoid lead was found removed and taped to the board. Both items replaced - unit OK.
Aiwa ADF-770 No F/FWD, R/W or play. This is a fairly sophisticated 3 head, dual capstan, 2 motor machine. Because the faults found on this deck occur regularly on other makes and models their repair will be described in some detail.
Because of the two flywheels there were two drive belts fitted and both of these were badly deteriorated and had become stuck to the flywheels. Due to inaccessibility it was necessary to remove the transport to get to the flywheel back plate. This was not too difficult - 2 screws on top, 2 on the bottom - and one screw holding the power switch which also must be removed. There is also a cable clip near this switch which must be unclipped. The transport was lifted up and out and the back plate removed (4 screws). The old belts were removed, fortunately in one piece, and measured. The diameter was calculated and reduced by 5% to allow for stretching. New belts fitted, transport installed back in machine.
Both capstans now rotating but no drive to supply or take-up hubs.
Transport removed again and cassette basket removed. To do this it is necessary to release one side of the transport frame. This is easily accomplished by removing a single screw from the frame (top left corner, viewed from rear), this allowing just enough room to remove the basket. This removed, the idler wheel that drives the supply and take-up hubs was visible. In common with many decks this idler (driven by the second motor) flips to one side or other dependant on motor rotation. Freedom of movement seemed OK so decided to check motor clutch. Lifting the hub brake arm with a finger exposes the 2 screws that hold the motor. These removed, the motor can be removed from the rear. On the motor shaft there is a simple friction clutch which can be pulled off the shaft with the fingers. Everything cleaned with alcohol and mating surfaces, which had become shiny, slightly roughened with fine glass paper. Also the tension spring was stretched very slightly so as to provide a bit more pressure. Everything re-assembled in reverse order, taking care to ensure that the leads from the heads exit from the rear of the transport through the gap provided and are not trapped under the transport (very easy to do). Unit powered up - unit OK
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