JPS6017069Y2 - Test switch for electrical equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a test changeover switch for electric equipment such as a portable VTR.

Generally, in a VTR, when measuring the constant running speed of a magnetic tape or the wow/flutter, the capstan servo system of the VTR is normally set to the recording mode.

In order to ensure tape compatibility when playing a magnetic tape recorded on a VTR with another VTR, it is necessary to measure the tape running speed with the capstan servo system in recording mode. etc., the rotational speed of the capstan motor is controlled so that the frequency of the countdown signal of the rotational speed detection signal of the capstan motor and the reference signal is equal, and during reproduction, the frequency of the regenerated control signal and the reference signal is In a VTR in which the rotational speed is controlled so that the frequencies are equal, the tape running speed during playback is the normal speed as long as the recording signal is recorded normally, so the tape running speed during recording is measured. There is a need.

By the way, the tape running speed or wah
To measure flutter, it is common to use a standard tape on which a signal of a constant frequency is recorded, and to reproduce the signal from the tape.

In a VTR, in order to measure the tape running speed, the capstan servo system must be set to the recording mode as described above, and the recording and reproducing system must be set to the reproducing state in order to prevent the standard tape from being erased, etc., and to reproduce the signal. There is.

To this end, it is conceivable to provide a dedicated switch for switching the capstan servo system so that only the capstan servo system is in the recording mode even when the VTR is being operated for reproduction.

Since this switch is not used by the user but is for testing purposes only, it is not easy to operate, and it is desirable that it can be operated in state 1 without disassembling the VTR.

For example, such a switch may be disposed deep in a hole in the VTR exterior, or it may be operated by removing a part of the exterior.

In order to dispose the switch deep in the hole as described above, a hole must be provided in the exterior, which may impair the aesthetic appearance, and dust may enter the hole.

Furthermore, if a part of the exterior is removed, this work becomes complicated.

The present invention eliminates the above-mentioned drawbacks, and provides a test changeover switch that does not damage the appearance of electrical equipment and can be easily operated by only the person conducting the test.

An embodiment in which the present invention is applied to a home portable VTR will be described below in detail with reference to the drawings.

The figure shows only a portion of the VTR related to the present invention.

In the figure, reference numeral 1 denotes a jack for connecting an external battery, and power supply current is supplied from the battery to the circuit of the VTR through the jack.

Reference numeral 2 indicates a terminal for supplying this current.

Reference numeral 3 designates a switch circuit, in which when the VTR is put into the recording state by operating the keyboard or the like, the input terminal 5 becomes 1LJ due to the voltage applied to the terminal 4 via the resistor R, and when the VTR is put into the playback state, the voltage applied to the terminal 4 becomes 1LJ. input terminal 5 due to the voltage
becomes 1HJ.

When the input terminal 5 becomes r''L, the switch circuit 3 changes so that the capstan servo system enters the recording mode. The capstan motor is controlled so that the frequencies are equal, and when the input terminal 5 becomes 1H, the switch circuit 3 is switched so that the capstan servo system is in the regeneration mode, and for example, the above-mentioned control signal and reference signal are switched. The capstan motor is controlled so that the frequencies of the two are equal.

6 is a Zener diode, and the Zener voltage of the Zener diode is selected to be higher than the voltage of the external battery.

Therefore, even if the external battery is connected to the jack 1, the transistor Q is off, so that the switch circuit 3 is not operated.

When testing the VTR, the transistor Q is turned on by putting the VTR in a reproducing state and applying a voltage equal to or higher than the Zener voltage plus the VBE of the transistor Q to the jack 1.

By turning on the input terminal 5, the input terminal 5 becomes rL, and the capstan servo system enters the recording mode, making it possible to measure the tape running speed and wow/flutter as described above.

As described above, the present invention is used in electrical equipment such as a VTR, and includes a jack for connecting an external battery and a switching means that is activated when a high voltage exceeding the voltage of the external battery is applied to the jack. This is a changeover switch for testing electrical equipment, which does not damage the appearance of the electrical equipment, such as the VTR, and can be easily operated only by the person conducting the test, by operating the switching means.

[Brief explanation of drawings]

The figure is a circuit diagram showing an embodiment of the present invention. 1...Jack, 3...Switch circuit.

Claims (1)

[Scope of utility model registration request] An electric device such as a VTR is provided with a jack for connecting an external battery, and a switching means that is activated when a high voltage exceeding the voltage of the external battery is applied to the jack, and when the switching means is activated, Above VT
A changeover switch for testing electrical equipment, characterized by switching electrical equipment such as R for testing.