Re: Flyback Troubleshooting help

  Well, I put the flyback back in and removed the following loads...

   1. 180V Secondary - Pulled rectifier diode
   2. Filament - Pulled current limiting resistor
   3. 24V Secondary - Pulled rectifier diode
   4. Focus Tap - Disconnected and insulated
   5. Anode - Disconnected and insulated

Unfortunately, after all this the switcher still shuts down due to
overcurrent. I tried disconnecting the deflection coil and it took about
a half second longer to shutdown but still did. So, that pretty much
removes the faults being related too ...

   1. Bad Picture Tube
   2. Overload on Secondary Windings
   3. Deflection Coil Support Circuitry (deflection capacitor and some
      inductors)

Pretty much the only thing left is right around the HOT at this point.
(2,3 and 5 'test' okay tho)

   1. HOT Discharge Capacitor (.1 @ 1600V)
   2. HOT Protection Diode (0.8A 1500V rectifier)
   3. HOT (BU-208)
   4. T1 - HOT Driver Transformer
   5. Q9 - Driver Transistor (D40P5)

I am going to have to order these parts... just so I have known good
ones on hand. I am using a BU-207 in one of my PCB's which should be
okay, it just can't handle the same power, which isn't a problem in the
1 second it runs before shutdown.

I started scoping around the HOT (base side) and T1 and the waveforms
get pretty distorted away from a square wave. I can post pics of those
if anyone is interested (still). :-)

jess

PS - I got some feedback from Mark @ Cinelabs that the Amplifone
'Ultra-Tuned' transformers are super finicky since they rely on
ferro-resonance.... after doing some searching... this is explained in
this patent from 1975 which explains this approach.. perhaps these
flybacks are a bit different beasts??
http://www.google.com/patents?hl=en&lr=&vid=USPAT3868538&id=N_o1AAAAEBAJ&oi=fnd&dq=ferro+resonant+flyback&printsec=abstract#v=onepage&q=ferro%20resonant%20flyback&f=false

On 1/18/2011 9:48 AM, John Robertson wrote:
> 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"

---------------------------------------------------------------------------
** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
** Please direct other questions, comments, or problems to chris@westnet.com
Received on Wed Jan 19 02:13:49 2011