Browse Prior Art Database

CRT Service Switch

IP.com Disclosure Number: IPCOM000105813D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Kiyotani, Y: AUTHOR [+2]

Abstract

Disclosed is a circuit for a CRT Service Switch which functions as both a service switch for line-cut-off adjustment of the CRT and a beam-on switch for the operational test of the CRT monitor. The terminals of the switch are connected to the vertical oscillation circuit and the video circuit to enable three selectable display modes: a normal operation mode, line-cut-off (vertical deflection stop) mode, and beam-on (full raster on) mode.

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CRT Service Switch

      Disclosed is a circuit for a CRT Service Switch which functions
as both a service switch for line-cut-off adjustment of the CRT and a
beam-on switch for the operational test of the CRT monitor.  The
terminals of the switch are connected to the vertical oscillation
circuit and the video circuit to enable three selectable display
modes: a normal operation mode, line-cut-off (vertical deflection
stop) mode, and beam-on (full raster on) mode.

      The figure shows the new circuit.  The voltage +5V is supplied
to a three-positional switch (2) through a resistor (1).  A terminal
1 of the switch (2) is a non-connection to select the normal
operation mode.  A terminal 2 of the switch (2) is connected to a
time-constant resistor (3) and a capacitor (4) of a vertical
oscillation circuit (5) to stop the vertical deflection when the
voltage +5V is supplied through the switch (2).  A terminal 3 of the
switch (2) is connected to a video output transistor (8) through a
resistor (7) and a switching transistor (6) to display beam-on
rasters when the voltage +5V is supplied through the switch (2).

      To display beam-on rasters, the CRT bias circuit (grid #1 or
grid #2) can also be used instead of the video circuit.