Hello,
A while ago I came into possession of a Facit A3400 Serial Terminal from the early 1990s.
Unfortunately it is not working properly and I am not really knowledgeable enough about electronics to know what to do with it.
When I turn it on it takes about 10-15 minutes before the screen comes on. What is displayed on the screen is constantly flickering white horizontal lines:

The screen does not change or react when I hook up something to the serial interface. I can connect to it from a host device but of course I cannot really see if it works or not because I can't see any output sent from a host on the screen. The vertical lines you can make out in the photo are burn-in from whatever software this terminal used to run.
I have checked the battery in the thing and it shows the correct voltage, but that might be me getting fooled by something.
Anyone have any suggestions on what might be wrong or what I should test?
Here are some more pictures of it:
http://imgur.com/a/V7kJ5