Video Signal Detector for Fault Isolation
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
The article describes a circuit arrangement and method for isolating a fault between a monitor, such as a CRT, and the adapter logic that drives the monitor. The circuit arrangement includes a plurality of cascaded single-shots, with appropriate time constant network, which are sequentially triggered by the video, V sync and H sync pulses. Given a video adapter circuit (Fig. 1) for a standard raster scan video monitor, the video signal is a signal that actually controls the beam that writes information on the face of the CRT. The horizontal sync (HSYNC) signal applies a pulse that initiates horizontal retrace of the beam. The vertical sync (VSYNC) signal provides a pulse that initiates vertical retrace of the beam. Loss of any one of the beam's three signals renders the display unreadable.