(1) Poor contact of the connecting signal cable between the graphics card and the monitor. You can re-plug the VGA connection plug in the case of power off, and carefully check whether the pins are bent and deformed, whether the signal line is broken, etc..
(2) If only a part of the screen, especially the four corners of the screen color deviation, generally due to strong magnetic interference. At this time, you can check whether the display is surrounded by strong magnetic devices, such as speakers, high-power power transformers, etc., try to move away from these devices, such as color deviation is still no improvement, then you need to consider the display to do the demagnetization process.
(3) Some monitors have a color temperature setting function, if the setting is wrong, it will also cause color casting failure, but the actual performance of this color casting is full of screen overall bias to a background color. This failure can be solved by re-adjusting the color temperature parameters correctly. If no matter how to adjust the color temperature parameters of the color deviation is still not better, the problem comes from the monitor's internal chromaticity output transistor is "soft breakdown", or bias potentiometer contact is poor. Encountered this situation, or the failure of the monitor to send professional maintenance personnel to deal with the best.
(4) We know that the TV and monitor, are relying on the electron beam scanning screen corresponding phosphor, producing a variety of colors. Control of the electron gun red, yellow, blue three primary colors of the amplifier circuit, we call the optic discharge circuit. If one of these circuits fails, the screen will be biased towards one color. Commonly, the visual amplifier transistor is damaged.
When the monitor has a lack of color, we can also use the OSD menu to help determine the part of the fault.
If the OSD menu is also the same lack of color, the fault must be the monitor's tailboard circuit, mostly CRT driver circuit or pre-vision amplifier circuit of the integrated circuit has a problem. If the OSD menu color is normal, and the image color is missing, this fault is generally broken in the signal line, the signal plug has a broken pin or short pin situation. Individual graphics cards can be set in the monitor output color temperature adjustment, when the color is too biased towards a certain color, but also gives the impression that the monitor is also missing color.
Generally manifested as a lack of red (the image is cyan) or green (the image is purple), or blue (the image is yellow), a few may be color confusion, but the image details are clear. If we use the monitor for a long time in this case, our eyes will tear and have a stinging sensation.
Check method: after the power off, check the signal cable plug of your monitor and the host, see if there is a broken pin inside (it is possible that it is not all gone, but there is, but only half of it is exposed), loose, crooked (folded on one side or connected with other pins), and then check if the graphics card is loose. If the above is normal, then the internal circuitry of the monitor is damaged.
When the whole screen appears red (R), green (G), blue (B), this situation is only the monitor internal circuit damage.
Note: The monitor and the host usually use a 15-pin D-plug, usually only 11, usually empty 9 and 5,11 pins, we do not have to feel strange, do not artificially use the big head pin to make up for the lack of pins.
Reminder: If you do not know very well, it is recommended to send repair, let the professionals deal with.
Normal is white, it is estimated that your video cable is not connected to a good cargo video cable bad pin. As for the meaning of the warning, is that you did not connect the keyboard, may not be connected properly or PS2 port is loose or damaged. The keyboard can be replaced with a USB keyboard.