Main shaft driving circuit as shown in the appended drawings, IC1601 (M54680FP) within the pulse width modulation (PWM) voltage regulator circuit for damageable parts, measuring C1612 anode is normal voltage IC {31} feet to 20 v (C1612 in circuit boards marked C12, omitted the first two digits, as are other components), PWM output voltage IC {30} feet (measured in L1602) to 0 v, suggests that PWM circuit is damaged. As an emergency treatment and improvement, at {30}, {31} foot external three-terminal voltage regulator, 7810 after the commissioning, can go to take in place, at this time if you don't make other actions can also bring back; But if the video reproduction, have walk fast, automatic stop protection after 3 seconds, and can't take any action. kHqservice manual download site
 kHqservice manual download site
 kHqservice manual download site
Refund with manual operation can be performed at this time: (1) counterclockwise with finger upon load of small wheel on the motor shaft, until the conduction band column back tape box. The first step (2) according to operating, belt box can rise and exit with warehouse. kHqservice manual download site
From the front tape movement situation analysis, can enter/back of motor and drive circuit is normal; Fast video reproduction of speed control circuit also has a problem. kHqservice manual download site
First each foot over the ground resistance measurement of FG generator () with a type 426 machine controls, essentially normal. The mount C1609 electrolytic capacitor (3.3 u F/v) 35 has leakage failure. C1609 expires M54680FP {and} - {and} feet in FG no FG signal amplification plastic circuit, video reproduction speed out of control. kHqservice manual download site
And if {16} feet outside the bypass capacitors C1607 u F / 16 (12 v) or at the foot of the 17} {outside the speed signal low-pass filter capacitance C1608 (47 u F / 16 v) failure, affects the torque ripple of IC internal detection and AGC circuit, causing the motor rotation is weak, and in and out of the fault with slow cannot even in a band. Therefore, Hitachi VT - 427 (426) the same applies to appear afore-mentioned a variety of movement disorder phenomenon should be paid attention to when check changing the electrolytic capacitors in the pasted on the main shaft components. Replacing capacitance carefully cleaning circuit board, and check for corrosion circuit line breaks.

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