Vectrex graphics problem

[s***@gmail.com]

I just picked up an old Vectrex and a batch of games and the machine
has some graphical issues. I've been reading about how the capacitors
will go out in these old monitors, and wonder if that's not what my
problem is.

I took a picture of what my screen looks like playing Pole Position.
Note that the vectors are thin lines with very pronounced dots at the
line intersections, there's a very bright spot in the center of the
screen, and lines extend outwards from that spot. Also note that the
text isn't displayed as text - even the boot screen has the text as
these rectangular boxes.

Loading Image...

Can anyone point me in the direction of what might be wrong with this?
Would a cap kit fix it, or do it's problems look to be deeper than
that?

Thanks in advance for any help!

[Eric Smith]

Post by s***@gmail.com
Note that the vectors are thin lines with very pronounced dots at the
line intersections, there's a very bright spot in the center of the
screen, and lines extend outwards from that spot. Also note that the
text isn't displayed as text - even the boot screen has the text as
these rectangular boxes.

Did you try turning down the intensity knob? If that doesn't have any
effect, possibly it's just the potentiometer that's gone bad.

[cNp]

Post by s***@gmail.com
I took a picture of what my screen looks like playing Pole Position.
Note that the vectors are thin lines with very pronounced dots at the
line intersections, there's a very bright spot in the center of the
screen, and lines extend outwards from that spot. Also note that the
text isn't displayed as text - even the boot screen has the text as
these rectangular boxes.

Looks like the easiest fix to me... you have to turn the brightness down...
it's a fairly easy to miss knob on the back of the console near the top.

Hope that works for you.

Another easy fix is if you don't find the Vectrex's 'charming' buzz quite so
charming, stick some parcel tape over the speaker grill... buzz greatly
reduced whilst only dampening the sound effects very slightly.

cNp

[Martin White]

And don't run it like that for very long!!

It won't take long at that intensity to get a nice dot of screen burn
in the middle of your scree :o)

[Tim Myrick]

I guess I should have mentioned about the brightness... I only turned
the brightness up to get a good photo. You really couldn't see anything
in the image when I had it down, so I cranked it up just long enough to
snap this image.

Even when the brightness is all the way down, as you turn it up, the
first thing that appears is that dot in the center of the screen. The
text is screwed up no matter how bright it is - even dimmed all the way
down, boxes appear instead of text. That happens even at the boot
screen.

Vectors shoot from that center light outwards while drawing others.
It's pretty trippy looking, but makes some games like Clean Sweep and
Minestorm unplayable. Pole Position is easily the most normal looking
of the games that I've tried, but it's definitely whacked. If you look
just above the car in the image, you can see where the lines from the
car angle up and intersect, then shoot straight towards that center
light.

Definitely different looking than a photo to compare to here:
http://www.mobygames.com/game/vectrex/pole-position/screenshots/gameShotId,64138/

[s***@gmail.com]

I should have mentioned, as from Google groups it isn't apparent... Tim
Myrick = shadwolf. I didn't realize with that first post that it was
going to display my email address, so I changed it for the second post
(and will change it back after this one). Thanks!

[Martin White]

Okay, hopefully someone will come up with something a bit more specific
becuase my experience on vectrex hardware is extremely limited having
only owned one for a few weeks.

Also a bit difficult to advise too much without knowing what you have
access to, however, i would suggest that the text blocks are probably a
logic board issue and the Z axis issue (the bright dot all the time)
could be either a logic board issue OR a monitor / power board issue.

If it were me, the next step i would take would be to connect up either
a scope or some other alternative display to the logic board so as to
confirm if the problem is still present on the external display. This
will tell yo which of the two boards is causing your problems.

Like i say, i'd be very surprised if the text blocks was anything other
than a logic board problem, although exactly what, you'll need someone
with more experience to advise you.

Hope that helps a bit!

Martin.

[Martin White]

Oh, PS: Completely forgot to answer your original question!

A cap kit MAY fix the Z axis intensity issue but I very much doubt it would
solve the text issue.

Time and time again in the raster world I see cap kits banded about as a
magic fix, but they're not unfortunately.

Good preventative maintenance though?, well, open to debate, but probably,
yes!


On 17/12/05 01:35, in article

Post by Martin White
Okay, hopefully someone will come up with something a bit more specific
becuase my experience on vectrex hardware is extremely limited having
only owned one for a few weeks.
Also a bit difficult to advise too much without knowing what you have
access to, however, i would suggest that the text blocks are probably a
logic board issue and the Z axis issue (the bright dot all the time)
could be either a logic board issue OR a monitor / power board issue.
If it were me, the next step i would take would be to connect up either
a scope or some other alternative display to the logic board so as to
confirm if the problem is still present on the external display. This
will tell yo which of the two boards is causing your problems.
Like i say, i'd be very surprised if the text blocks was anything other
than a logic board problem, although exactly what, you'll need someone
with more experience to advise you.
Hope that helps a bit!
Martin.

[Eric Smith]

Post by Martin White
A cap kit MAY fix the Z axis intensity issue but I very much doubt it would
solve the text issue.

Why? The text block issue *is* the Z axis issue.

[Martin White]

That's me not understanding how text is drawn again then!

Post by Eric Smith

Post by Martin White
A cap kit MAY fix the Z axis intensity issue but I very much doubt it would
solve the text issue.

Why? The text block issue *is* the Z axis issue.

[Tim Myrick]

I've got something to go on now at least - thanks everyone! I received
my cap kit for it from Zanen Electronics today so I'll go ahead and
install it and see what (if anything) improves. Also will go ahead and
pull out all the socketed chips out and clean the pins. Maybe I'll get
lucky with it...

[Jari Viitala]

Post by Tim Myrick
I've got something to go on now at least - thanks everyone! I received
my cap kit for it from Zanen Electronics today so I'll go ahead and
install it and see what (if anything) improves. Also will go ahead and
pull out all the socketed chips out and clean the pins. Maybe I'll get
lucky with it...

Good luck to you if your vectrex pcb is like mine (crap quality and really
hard to solder ;).

[Eric Smith]

Post by Martin White
A cap kit MAY fix the Z axis intensity issue but I very much doubt it would
solve the text issue.
Why? The text block issue *is* the Z axis issue.
That's me not understanding how text is drawn again then!

On the Vectrex, text strings are usually drawn as a series of horizontal
lines, with the intensity of the beam modulated off and on during the
line to form pixels. This is done because it usually takes less time
to display than stroking individual vector characters.

If the intensity is too high (due to the control, or a failure in the
electronics), it will just appear to be a group of lines. If the text
is small, and the focus isn't good, or there is "blooming", the group of
lines may appear to be a solid rectangle.

On a Vectrex with working intensity control set in a normal range and
proper focus, I don't think there's any failure mode of the digital
board that could result in normal text strings displaying as solid
blocks. Even if the digital part of the modulation (the 6522 VIA shift
register etc.) failed, the result would either be no text, or
horizontal lines, not a solid block.

Since the problem involved a bright dot in the center with lines from
that to all the other things being drawn, there clearly is an intensity
problem. It would be unsurprising for there to be a focus problem also.

[Alex H]

Post by s***@gmail.com
http://home.alltel.net/shadwolf/polepos.JPG
Can anyone point me in the direction of what might be wrong with this?

Bad 6522, maybe?


Alex