Quote:
Originally Posted by Adam
That second circuit up there ^ is basically what I did on my 20B1. I understand why you need a positive pulse if you connect to the CRT grid, and negative pulse on the cathode. But I notice that on the first page of that book posted, it says also to connect to whichever (grid or cathode) the video does not. I think I've had it work both ways (connected to the same place as the video, or the brightness control), so what is the reason for this?
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I'm not sure, but I suspect they're worried about the added capacitance messing with the higher frequency video signals.
I was able to download the 30A1 schematic from the ETF website. It looks like the 6K6 vertical output is transformer coupled to the vertical yoke windings, rather than directly coupled using an autoformer. So as the book points out, that ends up making the pulse negative on the yoke side of the transformer. I’m not sure where the proper place is to pick off the positive going blanking pulse on this set. Possibly directly off the plate of the 6K6 vertical output, but it may need to be divided down to a lower level. I’m just not experienced enough to say exactly what will work.