Plug-In Diagnostic Indicator Card
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Matrix printers are designed to have customer replaceable components, such as the wire matrix print head. However, the failure to provide proper printing may reside in the print head or in the print head driving circuitry. The cost of the machine is greatly increased if built-in diagnostic circuits are included to isolate the problem either to the print head or the driver circuits. This article describes a plug-in test card of inexpensive design and construction intended for individual use. The indicator card will be exercised by the normal print head driving circuits and will determine the source of the problem. Fig. 1 illustrates such a test card. The card 1 is provided with a PC (printed circuit) connector 2 for connection to cable that normally supplies power and driving signals to a wire matrix print head.