Re: Weird distorted shapes

Here's the full schem for the Deflection and HV...
http://www.dsbelec.iinet.net.au/Amp_Defl&HV_Schematic_Dez_FINAL.jpg

And here is a high res photo of the deflection board if it is of any help...
http://www.amazingarcading.com.au/2013_Proto-03.jpg

Here's the parts list for the deflection board...
http://www.dsbelec.iinet.net.au/deflection_pcb_a201015.htm

On Tue, Mar 4, 2014 at 12:39 PM, Colin Davies <
colin.w.davies@btopenworld.com> wrote:

> As Clay says....
>
> To be more useful I'd want to see the schematic for the
> deflection section and/or the layout. Curvey/distorted things like that
> could be related to opamp speeds or outputs getting too close to the rails
> or L/C or maybe power...
>
> ----- Original Message -----
> *From:* Joel Griffin Dodd <griffindodd@gmail.com>
> *To:* vectorlist@vectorlist.org
> *Sent:* Tuesday, March 04, 2014 8:21 PM
> *Subject:* Re: VECTOR: Weird distorted shapes
>
> I spoke to Doug Snyder from Atari who, apart from designing the System II
> hardware, also worked on a fair bit of the XY drives and outputs for many
> of their games. He said that there was cross talk between the Axis which is
> what was causing the curving and to isolate a letter on the scope then
> measure the voltage change for a stroke to see if there are unwanted
> voltage changes in the direction of the stroke that should remain straight.
> If there are non then it could be the yoke, if there are then the concern
> is that there is cross talk in the XY drives.
>
> Trouble is I have no idea how to isolate the stroke of one letter on my
> scope as I'm not that proficient.
>
>
>
> On Tue, Mar 4, 2014 at 12:07 PM, Colin Davies <
> colin.w.davies@btopenworld.com> wrote:
>
>> The problem looks more apparent in this other picture... See how the
>> 'straight' lines have a curve to them...
>>
>> https://www.dropbox.com/s/i1r76l4dif9vv2w/2014-03-02%2020.10.19.jpg
>>
>>
>> ----- Original Message ----- From: "Clay Cowgill" <c.cowgill@comcast.net>
>> To: <vectorlist@vectorlist.org>
>> Sent: Tuesday, March 04, 2014 6:46 PM
>> Subject: RE: VECTOR: Weird distorted shapes
>>
>>
>> >Look at this screen shot of another builders results...
>>>
>>>> https://www.dropbox.com/s/owa3vq5l6f0lgv2/100_3343_zps3521fb63.jpg
>>>>
>>>> Notice the blue is perfectly formed, but the green is all messed up
>>>>
>>>
>>> That looks to me as though the green channel amp is slow to turn on.
>>> The
>>> vectors look pretty straight-- they're just either 'fading in' (or
>>> 'fading
>>> out' depending on the direction of the draw I suppose) before reaching
>>> the
>>> end of the line. Could be a tube issue as well. Looking at the green
>>> color
>>> output vs. a deflection channel (or two) would probably show the problem
>>> on
>>> a scope.
>>>
>>> There might be a little high frequency 'jitter' in there somewhere that's
>>> causing the hash on some of the green verticals. Hard to tell with a
>>> picture-- really need video there. Also could just be that the shadow
>>> mask/dot pitch on the tube is pretty big and sometimes the green
>>> verticals
>>> are straddling the mask and appearing on one side or the other.
>>>
>>> For Joel's original problem, I would probably try to trace things through
>>> the deflection section with the scope-- put the Star Wars boardset X
>>> output
>>> on one channel and then follow X through the deflection section with the
>>> other channel. Set the volts/div to try to keep the waveforms about the
>>> same vertical size on the scope and compare them visually. You should be
>>> able to see that amount of difference/distortion on the screen so you
>>> should
>>> be able to see when it appears in the deflection board. (Hard to debug
>>> without knowing the design, but I'm assuming there's probably some sort
>>> of
>>> pre-amp that you could look at before it gets to a power-amp stage.)
>>>
>>> It does kinda look like its more prominent on short vectors which is
>>> probably a clue. To be more useful I'd want to see the schematic for the
>>> deflection section and/or the layout. Curvey/distorted things like that
>>> could be related to opamp speeds or outputs getting too close to the
>>> rails
>>> or L/C or maybe power...
>>>
>>> -Clay
>>>
>>>
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>>>
>>
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>>
>
>

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Received on Tue Mar 4 15:44:20 2014