Thanks FOL, I kinda knew I wasn't having these particular problems that require this fix since it only affects one particular monitor(which happens to be my favorite). But I still wonder if it could be a similar problem because it seems to be a power issue.
I posted about this a while ago but it is bugging me again now because winter is upon us, (colder). I get black screen for about 5-15 mins, (depending on room temperature), from first cold boot of amiga. I know the amiga has otherwise ooted normally because I can run things blind from a shell and hear sound, see HD access etc, or see composite output.
The reason I think it is power AND temperature related is that for a few more minutes after the screen does come up, if I do something to draw extra power, like insert a floppy, the screen goes black again for a few secs until disk access is done. After a further short period of warming up, everything is fine.
Indi is fine on all other monitors, monitor is fine with all other video sources. It is not the monitor warming up, if I leave it off while the amiga warms up, then turn it on, screen comes up straight awway.
The A600 has new caps and I've tried several PSUs.
Here's the old thread about this -
http://eab.abime.net/showthread.php?t=61717
But since then I have tested other CRTs which don't do this and other PSUs which still show the problem.