On Monday, 12 March 2018 21:01:17 UTC, whit3rd wrote:
On Monday, March 12, 2018 at 7:11:49 AM UTC-7, Jon wrote:
I have partially repaired an IBM mono monitor whose mains transformer had failed.

... the picture now sort of moves around but at a rate of 1-2Hz. Turning up the brightness shows a wavy left/right edge implying a few hundred Hz effect. But the effect is also vertical.

So, the 60 Hz magnetic field leakage from the new transformer is beating against the 62 Hz (or whatever)
vertical sweep. Magnetic field from the transformer reaches through the
glass into the electron beam path..

A conductive belt around the new transformer (can be made from copper tape, and soldered
at the seam) would be a good start. Reorienting the transformer (if possible) might help.
If the original transformer was shielded, now you know why...

Rewinding the original might be what's needed.


NT