Quote:
Originally Posted by peter_scott
The sync in these sets is inserted at the anode not the grid.
In the TV32 that I'm finding sensitive to ripple I have 600mV of ripple on the HT. I tried decoupling the anode feed to the sync separator and gave it a clean supply but it would appear that it is the oscillator that is problematic. Placing a modern 250uF electrolytic on the rail certainly helped.
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Peter,
You misunderstood what I was getting at.
The output of the vertical sync/integrator is physically connected to the anode, but it acts by producing a positive pulse at the grid. So the loading on the filter RC network is affected by the impedance at the anode and what you get at the grid also depends on the frequency response properties of the transformer.
So, ideally, to get the integrator correct, it should not be disconnected from the anode circuit and ideally the V sync pulse that is being monitored on the scope is monitored on the grid connection after it has been processed through the transformer as it is in use/operation.
Therefore, to get the best result, modifying the integrator (100k replaced with one gang of a 50k pot and the diode replaced with the other gang of the 50k pot and adjusting its so the sync pulse seen at the GRID is just free of H serrations) is done with the same conditions loading the filter that are happening it use.
To get the above, it's better that the valve is cut off and the oscillations have to be stopped and the scope placed on the grid connection.
In use just prior to the initiation of vertical fly back (the vert osc valve triggered into conduction) the Grid is negative, the sync pulse comes along at the grid at a + going pulse and triggers the valve into conduction. This is why I suggested the battery to disable the oscillations and put the DC grid voltage into the negative region to check the form of the sync pulse at the actual grid with the scope.