TECH: Asteroids

[marog_uk]

[ukvac] TECH: Asteroids
I've got an Atari Asteroids board that produces a display image the size of
a postage stamp!!! I have tried adjusting the X & Y pots but this makes no
difference. It's not the 19" monitor either as is works fine with an
Asteriods Delux board.

The image produced is about 1/2" by 1" and appears on the left, center of
the display. You can just make out the asteroids, ships etc. in game mode
and the criss-cross pattern in test mode. I connected up a scope to try and
amplify the small signal being generated, but couldn't get a stable image.

There is no sound either in game play mode - but I do get bleeps when I push
buttons in test mode.

I looked at a couple of 'Asteroids' trouble shooting websites - but nothing
like this is ever mentioned. I suspect it is something to do with the
Vector generator / amps - but don't really know where to start looking.

Anyone seen this problem before? Can anyone give me some pointers to which
components to test/replace?

Cheers,
Steve

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[retroshaun]

Re: [ukvac] TECH: Asteroids
And on a similar subject I STILL have my problem where the image
displayed is correct across the X but 1 "pixel" (one vector) thin in the
Y, across the center of the screen.

I was told the board was working OK after it being repaired so could it
be the monitor?
Can anyone fix this for me?

Shaun

Steve M wrote:

> I've got an Atari Asteroids board that produces a display image the
> size of
> a postage stamp!!! I have tried adjusting the X & Y pots but this
> makes no
> difference. It's not the 19" monitor either as is works fine with an
> Asteriods Delux board.
>
> The image produced is about 1/2" by 1" and appears on the left, center
> of
> the display. You can just make out the asteroids, ships etc. in game
> mode
> and the criss-cross pattern in test mode. I connected up a scope to
> try and
> amplify the small signal being generated, but couldn't get a stable
> image.
>
> There is no sound either in game play mode - but I do get bleeps when
> I push
> buttons in test mode.
>
> I looked at a couple of 'Asteroids' trouble shooting websites - but
> nothing
> like this is ever mentioned. I suspect it is something to do with the
>
> Vector generator / amps - but don't really know where to start
> looking.
>
> Anyone seen this problem before? Can anyone give me some pointers to
> which
> components to test/replace?
>
> Cheers,
> Steve
>
> _________________________________________________________________
> MSN Photos is the easiest way to share and print your photos:
> http://photos.msn.com/support/worldwide.aspx
>
>
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[John Bennett]

RE: [ukvac] TECH: Asteroids
A quick check to verify the board is to use a voltmeter on the AC voltage
range, put one probe on GND on the board and the other on the X & Y test
points in turn ... if you see 0 volts on the Y then the board is probably
dead - it should be about 3/4 of the reading you get on the X axis if both
size pots are adjusted to the same position.

If Y (and hence the board) is faulty I can help, otherwise you need a
monitor man!

Steve



DATA Imported from archives: originally posted by Steve Coule (steve@coule.freeserve.co.uk)

 

[John Bennett]

Re: [ukvac] TECH: Asteroids
sounds like a problem with one of your chasis transistors on the monitor
either one has died or a connection is not being made

if you dont know anything about monitors then leave it to some one else to
fix that does
as there is quite a bit of high voltage in their even when you have turned
the thing off

where are you located by the way

Mark



DATA Imported from archives: originally posted by markgwilliams (markgwilliams@ntlworld.com)

 

[retroshaun]

Re: [ukvac] TECH: Asteroids
I know *nothing* about moinitors (and not a huge amount about boards
either by the way!) so would definately need assistance. As the board
was already repaired and verified as working, I suspect its the monitor.
I am actually in Surrey but the machine (presently) is in the North East
(Durham area).

Can anyone offer help with this? Of course all costs will be covered,
goes withot saying.

Shaun

markgwilliams wrote:

> sounds like a problem with one of your chasis transistors on the
> monitor
> either one has died or a connection is not being made
>
> if you dont know anything about monitors then leave it to some one
> else to
> fix that does
> as there is quite a bit of high voltage in their even when you have
> turned
> the thing off
>
> where are you located by the way
>
> Mark
>
>
>
>

 

[P-Man]

Re: [ukvac] TECH: Asteroids
check the +15v and -15v regulators in the AVG section...

Andy

> I've got an Atari Asteroids board that produces a display image the size
of
> a postage stamp!!! I have tried adjusting the X & Y pots but this makes
no
> difference. It's not the 19" monitor either as is works fine with an
> Asteriods Delux board.
>
> The image produced is about 1/2" by 1" and appears on the left, center of
> the display. You can just make out the asteroids, ships etc. in game mode
> and the criss-cross pattern in test mode. I connected up a scope to try
and
> amplify the small signal being generated, but couldn't get a stable image.
>
> There is no sound either in game play mode - but I do get bleeps when I
push
> buttons in test mode.
>
> I looked at a couple of 'Asteroids' trouble shooting websites - but
nothing
> like this is ever mentioned. I suspect it is something to do with the
> Vector generator / amps - but don't really know where to start looking.
>
> Anyone seen this problem before? Can anyone give me some pointers to
which
> components to test/replace?
>
> Cheers,
> Steve