Re: Flyback Troubleshooting help

Jess Askey wrote:
> Okay, this is looking better now....
>
> This is the best I could lock onto the ringing at the tip of the main
> pulse... this is *very* zoomed in (.2us/div) and I couldn't quite get
> it to trigger ahead of the main pulse. Apologies for the crappy
> lighting...
>
> http://gamearchive.askey.org/Video_Games/Manufacturers/Atari/monitors/amplifone/raster/images/secondary_ring_15k.jpg
>
> .... but is exactly what I should see. This is pulled off one of the
> secondaries.
>
> Additionally: I was feeding my primary with 10VPP. Upon measuring my
> secondaries, they all came out just about right comparing to the
> computed ratios from 120V down to 10V. I even had a whopping 50VDC on
> my anode.
>
> So: Seems this transformer must be good. Pretty exciting that I had it
> taken apart to the extent that I did and managed to get to back
> together (quite easily too). I will re-silicone it tomorrow and move
> back to troubleshooting the support circuitry. Since I have another
> flyback and my test rig is stable, I will ring that one tomorrow too
> and then report back.
>
> Has anyone run into either the deflection capacitor or the retrace
> capacitor breaking down at operating voltages? I still can't believe
> that I have two PCB's with the same problem. Shit, maybe my picture
> tube has a short? Can I run a flyback with the Anode and focus
> disconnected?
>
> thanks for staying late at the party!!
>
> jess
>

Hi Jess,

I realized the reason you weren't seeing any ringing was the core was
outside of the coil so at that point all you had was a coil - with the
core in place then you would get the ringing you show today. Figured
this out after going to bed last night...

As for running the flyback with no load on the Anode and focus lines -
no problem, I do this all the time. I have a ceramic cup on my test
bench that I stick the anode cap into when I am testing chassis to avoid
ouchies.

John :-#)#
>
> On 1/17/2011 5:27 PM, John Robertson wrote:
>> Jess Askey wrote:
>>> Here is the main primary being rung @ 15KHz with a .047uf cap in
>>> series with it, there are no other windings on the core with it...
>>> but I can throw more on if needed.
>>>
>>> http://gamearchive.askey.org/Video_Games/Manufacturers/Atari/monitors/amplifone/raster/images/main_primary_ring_no_secondaries.jpg
>>>
>>> I thought that Raster flybacks where supposed to have spacers
>>> between the cores? This one doesn't have any.
>>>
>>> jess
>>>
>>
>> That image does not look good to me, the signal is damped way too
>> quickly. You should see a train of decreasing rings like the other
>> picture you posted. I suspect the red coil has a shorted winding
>> after all - assuming you are only driving the red coil and it is out
>> of circuit as in your most recent picture above.
>>
>> As for the spacer, it all depends on the design. I am fairly sure
>> most flybacks do NOT have a spacer between the two halves, what they
>> usually do have is some sort of glue...
>>
>> John :-#(#
>>>
>>> On 1/17/2011 2:35 PM, Rodger Boots wrote:
>>>> Just grab a capacitor (.1 to 1 uF or so) and put it in series with
>>>> the generator output. You just need to get rid of the DC component
>>>> of the signal (transformers get weird around DC).
>>>>
>>>>
>>>> On Mon, Jan 17, 2011 at 3:19 PM, Jess Askey <jess@askey.org
>>>> <mailto:jess@askey.org>> wrote:
>>>>
>>>> My generator doesn't have a DC offset, I will have to build
>>>> one. I just have a waveform generator IC that I breadboarded up
>>>> really quick... I will see if I can get a waveform generator
>>>> locally that has that feature.
>>>>
>>>>
>>>> On 1/17/2011 2:16 PM, Rodger Boots wrote:
>>>>> Does your generator have a knob marked "DC offset"? If so,
>>>>> set it for a -4 to +4 volt square wave. Using 0 to +8 volts
>>>>> isn't going to give you useful readings.
>>>>>
>>>>>
>>>>> On Mon, Jan 17, 2011 at 2:19 PM, Jess Askey <jess@askey.org
>>>>> <mailto:jess@askey.org>> wrote:
>>>>>
>>>>> Okay, I put the standalone LOPT onto my square wave
>>>>> generator (unfortunately my generator can only supply
>>>>> 30ma) so Im not sure that is enough.
>>>>>
>>>>> Here is the signal before attaching the LOPT.... 15KHz 9vP-P
>>>>>
>>>>> http://gamearchive.askey.org/Video_Games/Manufacturers/Atari/monitors/amplifone/raster/images/generator_output_15k.jpg
>>>>>
>>>>> Here is the primary with that signal attached...
>>>>> secondaries are exactly the same waveform, yet in
>>>>> different ratios (and those ratios are not correct)
>>>>>
>>>>> http://gamearchive.askey.org/Video_Games/Manufacturers/Atari/monitors/amplifone/raster/images/lopt_ringing_15k.jpg
>>>>>
>>>>> Doesn't look right.
>>>>>
>>>>> When I read a DC voltage on the Anode cap, I have 2.2VDC,
>>>>> pretty low. :-(
>>>>>
>>>>
>>
>>
>> --
>> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
>> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
>> www.flippers.com
>> "Old pinballers never die, they just flip out"
>>

-- 
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
                 www.flippers.com 
"Old pinballers never die, they just flip out"
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