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Argus25 · 4th Oct 2019, 11:30 pm

One interesting thing about getting the V sync pulse filter right in the set, if the output from the filter is disconnected from the V osc, it changes its properties. So ideally to do it, the V osc is stopped and the scope is put on the valve's grid, so the final sync pulse you see there also includes the effects of the blocking osc transformer and is the actual pulse that triggers the V osc.
Yet although RCA recommended stopping the V osc, they did not explain how it should be done.
Looking at the TV22 circuit as one example in post 69, I think the best way to do it would be with a 9V battery, positive to ground and negative connected to C4. This will prevent C4 charging up and it will hold the grid negative keeping the valve cut off. Then the scope can be placed on the valve grid to look at the sync, Then the resistors in the filter adjusted to get the correct result where the H serrations are just eliminated.

20V ripple seems very extreme for the supply of a V osc.

4th Oct 2019, 11:30 pm	#123
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Bush TV22 with TC184 B3 converter. One interesting thing about getting the V sync pulse filter right in the set, if the output from the filter is disconnected from the V osc, it changes its properties. So ideally to do it, the V osc is stopped and the scope is put on the valve's grid, so the final sync pulse you see there also includes the effects of the blocking osc transformer and is the actual pulse that triggers the V osc. Yet although RCA recommended stopping the V osc, they did not explain how it should be done. Looking at the TV22 circuit as one example in post 69, I think the best way to do it would be with a 9V battery, positive to ground and negative connected to C4. This will prevent C4 charging up and it will hold the grid negative keeping the valve cut off. Then the scope can be placed on the valve grid to look at the sync, Then the resistors in the filter adjusted to get the correct result where the H serrations are just eliminated. 20V ripple seems very extreme for the supply of a V osc.