Scandoubler problem - hardware fault?

[Damion]

Is the Power Computing version made by DCE? If
so, the picture should reamain stable in the
pass-through modes. I've used DBLNTSC before
for hours with no problems.

[Damion]

What motherboard revision do you guys have?
I actually had to return the first SD I bought
because white colors would tear away and "bleed"
through the display. The second one I got has
been working flawless.

[Damion]

@Amiwin

Thanks for helping!:-)

No prob!

On further thought, here is a good way to determine
the cause of your video problem:

1. If you don't already have one, pick up a 23 to
15-pin video adapter so you can hook your VGA
monitor directly to the amiga video port
(about 15 Euro/USD on ebay or from any amiga
dealer).

2. Select the offending "30khz" video mode and save.

3. Turn off the machine, and connect the monitor
directly to the amiga 23-pin video port via the
adapter.

3. Fire up the machine and let it run. If the display
remains stable, you can be reasonably sure the fault
is with the scandoubler. If the display begins
to distort ala before, you probably need to have
the motherboard "timing" repairs made.

If you do end up needing the "timing" fixes,
there are a few people on this board who
have done them before and can help, or
I'm sure someone can recommend a shop
capable of making the repairs. Apparently
all but some Commodore revisions and the
last of the Escom machines may need "the fix".

Hope this helps!

[Damion]

Here're some threads about A1200 video problems:

http://www.amiga.org/forums/showthread.php?t=1455

http://www.amiga.org/forums/showthread.php?t=1549

Here's a site about the "timing" problems and
their relation to some "Apollo" cards:

http://www.haigh1.freeserve.co.uk/Apollo_crashing.htm

My bet would be on the SD itself being the
problem, as it works fine without it. It's
entirely possible though that a "timing"
fault could somehow affect the display only
when "passed through" the SD, but it seems very
unlikely.

[Damion]

Not exactly, that's a different problem related
to video problems mainly with RF output on later
motherboards.

There were early NTSC US C= boards that exhibited
this tearing problem (obviously nothing to do
with "EC" regulations) and not just the 1D4
revisions.

The confusing issue is whether or not the
"timing fixes" involving Alice and Budgie
have anything to to with video problems, or
only affect accelerators/controllers/etc.
The fix involves removing capacitors under
Alice, so I'd say it's likely. It would be
nice if there was a single resource somewhere
that gave some more detailed specifics.