Abstract: A method for checking test points of printed circuit board layout text data before plotting the printed circuit board layout map is disclosed. Firstly, providing a printed circuit board layout text data, which may be plotted as a printed circuit board layout map. Next, collecting the name data of a number of nodes from the layout text data. Subsequently, collecting the layout data of a number of useful test points from the layout text data. Then, analyzing the effectiveness of these useful test points for selecting a number of effective test points from these useful test points; Subsequently selecting a real test point of each of the nodes from these effective test points. Lastly, analyzing the distribution data of these nodes and the real test points.

Abstract: A monitor includes a display panel, a displaying circuit, a connector and a self testing circuit. The self testing circuit has a testing signal generator, a switch circuit and a detecting circuit. When the detecting circuit detects the video signals transmitted from the computer, the detecting circuit switches off the switch circuit so as to avoid the testing signal generated from the testing signal generator being transmitted to the input port of the displaying circuit. When no video signals transmitted from the computer are detected, the detecting circuit switches on the switch circuit to allow the testing signal generated from the testing signal generator to be transmitted to the displaying circuit.

Abstract: A display device has a display screen, a display circuit, an image correction circuit, a timing pulse generator electrically connected to the image correction circuit, and a switch circuit. The switch circuit has a switch electrically positioned between the timing pulse generator and the image correction circuit, and a key electrically connected to the switch for controlling the state of the switch. The switch controls the transmission of a sampling timing pulse from the timing pulse generator to the image correction circuit. When the key is pressed, the switch is activated to permit the sampling timing pulse from the timing pulse generator to transmit to the image correction circuit. The image correction circuit will then perform an automatic image correction to an image frame displayed on the display screen depending on screen frame signals transmitted from a host computer.

Abstract: A protecting circuit for a horizontal transistor used for protecting the horizontal transistor of a horizontal deflecting circuit in a cathode ray tube. The protecting circuit comprises a switching circuit and a power sensor. The switching circuit is coupled to at least one sub capacitor of a S-character correcting loop. When the switching circuit is on, the switching circuit further connects the sub capacitors and the main capacitor of the S-character correcting loop in parallel. The power sensor is for detecting whether the D.C. voltage source is on. When the power sensor detects that the D.C. voltage source is off, the power sensor will turn on the switching circuit. The invention reduces a surge of the cross voltage VCE of the horizontal transistor when the system is off, therefore the invention achieves the goals of protecting the horizontal transistor and raising yield of the products.

Abstract: A protecting circuit for a horizontal transistor used for protecting the horizontal transistor of a horizontal deflecting circuit in a cathode ray tube. The protecting circuit comprises a switching circuit and a power sensor. The switching circuit is coupled to at least one sub capacitor of a S-character correcting loop. When the switching circuit is on, the switching circuit further connects the sub capacitors and the main capacitor of the S-character correcting loop in parallel. The power sensor is for detecting whether the D.C. voltage source is on. When the power sensor detects that the D.C. voltage source is off, the power sensor will turn on the switching circuit. The invention reduces a surge of the cross voltage VCE of the horizontal transistor when the system is off, therefore the invention achieves the goals of protecting the horizontal transistor and raising yield of the products.

Abstract: A monitor includes a display panel, a displaying circuit, a connector and a self testing circuit. The self testing circuit has a testing signal generator, a switch circuit and a detecting circuit. When the detecting circuit detects the video signals transmitted from the computer, the detecting circuit switches off the switch circuit so as to avoid the testing signal generated from the testing signal generator being transmitted to the input port of the displaying circuit. When no video signals transmitted from the computer are detected, the detecting circuit switches on the switch circuit to allow the testing signal generated from the testing signal generator to be transmitted to the displaying circuit.