Re: Weird distorted shapes

They would have to be WAY low in value to cause a problem. I can't read
the values from the photo.

The theory is that what you actually see on the screen is determined
by the *current
through* the yoke. What those two resistors feed back is the *voltage
to*the yoke.

What you had on an early screenshot looked like the lines were being drawn
*exponentially* instead of *linearly*. This suggested that the amplifier
was either clipping (not enough input voltage to monitor, unlikely if using
the correct power supply transformer for this game) or voltage limiting
(due to too much feedback from a low value R14 & R72).

Wild speculation from someone miles away from the actual problem.

On Wed, Mar 5, 2014 at 10:54 AM, Joel Griffin Dodd <griffindodd@gmail.com>wrote:

> Rodger, could you expand on that a little so I can understand it more.
>
>
> On Wed, Mar 5, 2014 at 7:34 AM, Rodger Boots <rlboots2@gmail.com> wrote:
>
>> Try running WITHOUT R14 & R72.
>>
>> Doesn't look like correct parts are on the board. If these are low
>> enough in value they could cause what you have.
>>
>>
>> On Tue, Mar 4, 2014 at 2:44 PM, Joel Griffin Dodd <griffindodd@gmail.com>wrote:
>>
>>> 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
>>>>>>
>>>>>>
>>>>>> ------------------------------------------------------------
>>>>>> ---------------
>>>>>> ** Unsubscribe, subscribe, or view the archives at
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>>>>>> ** Please direct other questions, comments, or problems to
>>>>>> chris@westnet.com
>>>>>>
>>>>>
>>>>> ------------------------------------------------------------
>>>>> ---------------
>>>>> ** Unsubscribe, subscribe, or view the archives at
>>>>> http://www.vectorlist.org
>>>>> ** Please direct other questions, comments, or problems to
>>>>> chris@westnet.com
>>>>>
>>>>
>>>>
>>>
>>
>

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Received on Wed Mar 5 12:55:47 2014