Re: Asteroids and 'wiggly' diagonal lines

From: someotherguy <someotherguy_at_mediaone.net>
Date: Sat Jan 12 2002 - 17:13:52 EST

I'd like to hear from folks' experience trying to fix this, as well. It
seems more than one Asteoroids I've had exhibited this behavior to a certain
degree. Usually it appeared that certain areas of the screen, as you pass
through them, there's a slight disruption as if there is an "invisible line"
in that area of the screen. Well, the one I have now, this area is
dead-center so that when you start each round, with your ship in the middle
of the screen, it is very obvious.

Richard

----- Original Message -----
From: "Phil Morris" <phil@morris0.fsnet.co.uk>
To: <vectorlist@synthcom.com>
Sent: Saturday, January 12, 2002 4:48 PM
Subject: VECTOR: Asteroids and 'wiggly' diagonal lines

> After looking at loads of web sites and reading old messages, I have some
> possible theories as to what is causing the 'wiggly' diagonal lines on my
> Asteroids game. However, all the descriptions I have seen don't exactly
> match the fault with my particular game, as in one place in particular the
> lines are even more 'wiggly'!. Vertical and horizontal ines also look
> slightly 'bitty' as every other 'pixel' (I know, they're not pixels!)
there
> is a lighter one, so giving the bitty appearance. Some possible causes I
> have seen mentioned are bad DACs, noisy power supply (I've recently
> replaced 'Big Blue' in the PSU, but haven't yet replaced the large blue
> caps in my G05-801's regulator board - they're on order), bad edge
> connector contacts (???) and possibly even the second or third stage
> transistors (that includes the MPSU57's, MPSU07's, etc and the larger
> 2N3792's and 2N3716's on the large heat sink). Adjusting the linearity
pots
> on the deflection board does not help the wiggly lines problem.
>
> So I'm scratching my head a bit, tempted to tackle the possible solutions
> one by one, well aware that *neither* could be the cause of the problem,
> but at the same time thinking I should at least ask the experts here to
see
> what they think. And no, I'm not being lazy either, I've spent many hours
> reading up and trying to suss this out, but my limited (but slowly
> expanding) knowledge doesn't exactly help.
>
> As they say, a picture is worth a thousand words and maybe I'm
> 'mis-reading' or even mis-reporting the fault, so here's a picture of the
> game in test mode:
>
> http://www.morris0.fsnet.co.uk/Test_Mode1.JPG
>
> Note: it's 700K! Also, I've since adjusted the linearity pots on the
> deflection board so the top triangles are now more even.
>
> I'm afraid the picture is a little blurred - that's the camera/my
> photography but it's the best of the bunch, the actual display is much
> sharper. Even so, it's good enough to see the wiggly lines I think. Oh,
and
> the coloured areas are reflections. :)
>
> The most interesting segment is the intersection of two diagonals just
> below the 'brightness' test lines in the centre of the display - this
> intersection results in a far more major 'wiggle' - looks like someone was
> drawing and the pencil slipped to the left a couple of times! The ship
also
> has a very short (about 2 or 3mm) horizontal line sticking out of it's
nose
> if I point it directly left or up/down a little from there.
>
> I've also noticed that while playing a game, at certain screen areas, if
an
> asteroid explodes then it can sometimes generate a few extra but extremely
> brief horizontal or vertical lines, maybe up to a an inch or two long.
This
> is very intermittent though.
>
> Some other points worthy of note re the picture:
>
>
> The edges of the picture look *FAR* more 'bowed' than they really are
> (they're really fairly straight), but having said that, there is a
*little*
> pincushioning, slightly inwards on the left vertical line (and more so
> towards the top left hand corner), and a very slight upwards bowing on the
> topmost horizontal line.
>
> There is also a noticeable curve downwards and to the left in the
> horizontal plane from about the centre of the screen and to the left of
it,
> increasing towards the left edge. The right hand side looks fine. This is
> more noticeable on the player 1 score and the text that appears asking for
> your initials to be input.
>
> As I mentioned, I have since adjusted the linearity pots and the elongated
> diamonds on the top half are now somewhat less elongated. The worst
> distortion was in the upper left corner and there is still some there,
> despite adjusting the linearity, but all corners were affected to some
> degree. When playing the game this was manifested by, especially in the
top
> left corner, any objects entering any corner or going off the top or
bottom
> (but not left or right edges) becoming noticeably stretched vertically.
> It's improved now, but still not perfect. Sorry, I couldn't get a decent
> picture of this.
>
> Also note: the fine vertical lines in the area of the I I and the zero's
> are fine scratches on the surface of the tube. It was like that when I got
> it. :(
>
>
>
> Thanks for any help you can offer,
> Phil
>
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Received on Sat Jan 12 14:36:13 2002

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