strange diagonal lines on my monitor

Hello! Sorry to have to query such a boring thing, but I have searched the web and the messageboard and come up with nothing on this topic. I am not especially IT-literate so please excuse me if this problem seems obvious to you.

I turned on my monitor this morning at work (as you do) and when the screen warmed up, it was the same as usual. I did some work in Word and Outlook (not too much!), then went to get coffee.

When I came back, my Word screen (usually grey) had lighter grey lines running diagonally across it. I thought this was strange so I checked the monitor cables, rebooted the machine, turned off the monitor for 15 minutes, pressed the mysterious degauss button; everything I could think of short of opening the cursed thing up, but the lines remain.

My monitor is pretty old (I think it’s 3 years old, but I’ve only been working here since September, so I’m not sure) and I was wondering whether there could be any simple solution I’m not thinking of.

Thanks for bearing me!


Make model & manf is printed on the back of the monitor. Sure are a lot of monitor questions today. Usually its a magnetic item nearby that can cause this to happen.

What you see are “Retrace Lines.”

Short tutorial:
Monitor and TVs (but not old Atari video games) are raster scan.
An electron beam is directed to top corner of CRT (Cathode Ray Tube) and then moved side to side, down a step, side to side, down a step, …
The beam hits the phosphor and illuminates it.
This beam goes up and down 60 times a second and back and forth at tens of thousands of times a second depending on resolution of the monitor. It happens so fast and your eye reacts so slowly that you see a picture.
When the beam gets to the bottom of the screen it is blacked out and redirected to the top. But on your screen the blacking out is not being done due to a “Blanking Circuit” failure.
The reason you see a zigzag pattern is that the horizontal circuit, back and forth part, is still working while the “Retrace,” bottom back to top part, is being performed.

Cure could be as simple as adjusting B+ (power supply), or the HV (30-60,000 volts) to the flyback transformer, or as complex as replacing components in the Blanking Circuit.

This is a “How much is that yacht?” question.
If you have to ask then …

Color Appendex:
The beam is actually three beams directed to three color point on phosphor screen. There are a set of magnets on the neck of the CRT to “converge” the three beams. A magnet near CRT will bend one color beam into a different color part of screen giving wrong colors.

Very often, that’s a problem with the screen voltage. The adjustment for that is nearly always found on the flyback transformer (the one with the fat wire that runs to the back of the CRT. The sharpness control is found there too, usually.

P. S. Found whilst looking for the term vidicon in another thread.