Re: Flyback Troubleshooting help

  Im going to go put a low value resistor in series with the horizontal
deflection coil so I can scope the voltage and see the current going
through the deflection coil (an inductor) and I *should* have a sawtooth
(or at least a trapezoid) there. After thinking about the ringing point
that Rodger made, I don't think my statement made any sense as I
wouldn't see a sawtooth from ground to HOT collector. However, I should
see a sawtooth voltage across any resistive element in series with the
H.Deflection coil. Reading directly across the H.Deflection woudn't work
because it is an inductive load and the voltage is not representative of
the current and the real thing that has to be a perfect sawtooth is the
current through the H.Deflection coil.

On 1/17/2011 12:08 PM, Jess Askey wrote:
> That *is* a good question... why is it ringing? The LOPT primary is
> also on the horizontal deflection coil so it should be a nice solid
> sawtooth for correct deflection.... maybe I have a bad retrace or
> deflection capacitor?
>
> The damper diode is connected and tested good. HOT is tested and
> good... correct part. Yoke is connected and is the correct yoke. I put
> a similar raster yoke on it just for fun and behavior is the same.
>
> The filter cap is good (new) on the 120V B+ to the HOT and LOPT. If I
> scope the 120V (im running this at 36V) supply, it is actually quite
> stable with negligible noise.
>
> On 1/17/2011 12:56 AM, Rodger Boots wrote:
>>
>> John, it's a raster monitor, not vector.
>>
>> So why is it ringing in the first place? Is the damper diode
>> connected? Is the horizonal output transistor the correct part? Is
>> the correct yoke winding connected? Is the filter capacitor on the
>> power supply to the output transformer working (should be DC to the
>> transformer, very little AC).
>>
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Received on Mon Jan 17 14:39:12 2011