Re: Asteroids and 'wiggly' diagonal lines

If The HV cage cover is off, you can cause this symptom.

Also, the caps at location C86 and C87 on the game PCB may need changing
(electrolytic 470uf 35v axial) I had a board that played, but looked like
'lightening' around the vectors, these 2 caps were broken off completely.

I would also make sure the contacts in the connectors are clean, a bad
ground could possibly cause this also :)

Along with interference from other nearby electrical devices...

Andy

----- Original Message -----
From: "Phil Morris" <phil@morris0.fsnet.co.uk>
To: <vectorlist@synthcom.com>
Sent: Saturday, January 12, 2002 9:48 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 15:50:02 2002