I've recently tried to make conversion from EGA (probably, couldn't get scope to verify) to VGA to replace an old factory CRT monitor to LCD.
Screen displays fine but it appears to shake vertically in a terrible manner that make it hell to read information from it. Video presentig the issue is linked below. What may be possible cause of this issue?
EDIT: Some informations that might appear to be useful (most have been asked in comments section):
i'm using GBS-8200 CGA/EGA to VGA converter (manual for this one specifically is here: arcadeworlduk.com/content/CGA-VGA-Manual.pdf),
(GROUND->black, GROUND->none, VS->white, HS->none, S->yellow, B->blue, G->green, R->red)
- frequencies on yellow/white pins are: yellow-15-17Hz, white-18-21Hz