Maybe someone just tried to refurbish it and screwed it up.
Or someone got a little lazy on an assembly line in japan 25 years ago or something.

Hi!

I was testing one DMG Game Boy model, and there are vertical lines all over the screen.  I'm not asking how to fix the standard vertical line issue.  The strange thing is that all the vertical "bad" lines have the same amount of good vertical lines between them, 7 lines.  And I can add more strangeness to the matter.  Both the No-Nintendo and the Nintendo logo appear stripped because of the white lines, but when I put contrast to maximum, all the lines show up.  So I assume they are not bad lines at all.

I tried loading a game, the drawing duck cart, and the first splash screens shows correctly.  This screen has some tiny white letters upon a black background.  It seems the letters fall inside the black rectangles, this is why it shows ok;  in fact all the letters appear ok thought the game. And the rest of the game has the same black or white.  On some screens you can se the lines from the top to the bottom of the lcd, and in others you can see the lines shortened, but they still appear.

I can see that the screen has, sort of, been transplanted into this DMG, as I can see that the solder on the solder pads of the lcd ribbons are not the original one.  I've tried if there is some bad contact but I've found none.  I will upload some pictures, but let's see if someone has seen this strange issue.

Thank you all!