I have an AppleColor composite monitor (A2M6020) that only shows green-scale. The color toggle switch on the front doesn’t change anything. I have plugged the monitor into multiple devices with the same result. nothing looks visibly wrong on the inside.

monitor at the color button turned on

back side of crt

enter image description here

Any ideas?

  • That button right of the controls should toggle it between full-color and green modes. What does it do with yours? Here's a link to the manual: apple-iigs.info/doc/fichiers/…
    – Janka
    Commented Jan 31 at 22:01
  • @Janka it simply shifts the picture to the right by a few millimeters. it still keeps everything green
    – help
    Commented Jan 31 at 22:02
  • I think the problem is with the video signal then. Unfortunately there's different FBAS video signals out there and old computer monitors can usually only display the single one they are designed for. That you can actually see anything is pure luck.
    – Janka
    Commented Jan 31 at 22:05
  • @Janka my apple iic displays in all green as well, which is odd because that is what this monitor is designed for. I’m trying to fix it for use with the apple, and the xbox 360 was just the nearest composite output i had.
    – help
    Commented Jan 31 at 22:08
  • Has this thing ever displayed anything in color? I wonder, maybe there's a series of "color" monitors out there which has been sold to the government for schools that has a green CRT as a cost-saving measure.
    – Janka
    Commented Jan 31 at 22:11

1 Answer 1


From the moire at the first photo one can deduce that the tube does emit some blue in addition to the green.

While cable or video signal path issues may be the reason, there is also pretty much a common failure mode for picture tubes where the basic colors fade one by one.

In this particular case look like you have some blue and absolutely no red.

If this is the case, the damage to the tube is irreversible.

I the old times, one would try to improve the situation for a while by increasing the heating voltage of the tube. This may or may improve the situation and will be good for a week or a year, depending on your personal luck.

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