Re: Flyback Troubleshooting help (Solved!)

  Okay, I have a resolution to this problem... just a few more
breadcrumbs of info...All the previous messages in this thread ended up
concluding that the flyback was probably good.

   1. I double checked all other components around the HOT on the PCB or
      put in new ones
   2. After all of that I still had the supply shutdown due to overload.

I spoke to Mark Shostak about the Cinelabs replacement he did on the
Vector HV transformer. His comments were...

    * The Amplifone 'ultra-tuned' transformers are extremely finicky
      about any inductive abnormalities
    * When in doubt, it is highly likely that the transformer is the problem

So, I found that I had some flybacks from a WG K7000 monitor laying
around. I thought I would try hooking up the primary only of it to the
Amplifone and see what happens. Well, the board came up fine and I had
decent 24VAC on one of the secondaries.

Conclusions:

   1. the Amplifone Raster Flyback *is* bad even tho it rings (I think I
      had at least 7 solid ring pulses)
   2. The Wells-Gardner K7000 flyback might work as a suitable
      replacement with PCB modifications, it has all the voltage taps
      (filament, +24, +15, +180, focus, screen, anode) that the
      amplifone uses.

Im going to see if I can get the K7000 flyback working fully this
weekend and will report back.

jess

On 1/19/2011 12:12 AM, Jess Askey wrote:
> 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"

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Received on Thu Jan 20 16:41:01 2011