Re: Weird distorted shapes

 And while I'm in wild speculation mode, make sure F1 & F2 are fast-blow
fuses, not those slow-blows that look like a coil of wire. You don't need
more inductance in this circuit.

On Wed, Mar 5, 2014 at 11:55 AM, Rodger Boots <rlboots2@gmail.com> wrote:

> 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
>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>>
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>>>>>> ---------------
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>>>>>> chris@westnet.com
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>

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Received on Wed Mar 5 13:04:25 2014