|
OK, I'll try the seven-second test later today and observe the results.
I spent some time yesterday playing with different values for R86, using a handful of 25-watt resistors that I picked up locally. It is a cumbersome and very slow process, to clip a resistor (or series-ed resistors) into place, slide the chassis back into position, turn the set back on, observe the result, and try to compare the pattern to what you saw before. I tried taking photos with the camera on a tripod, and noting the resistor values for later comparison.
Subbing the capacitor values was so much easier with a decade box, where I could keep my eyes on the screen and flip between different values, back and forth, looking at different parts of the screen, etc.
Anyway, yesterday's results were not very informative. When I put a crosshatch pattern back on, I realized that the linearity wasn't quite as good as I remembered.
I also realized that I had begun with the TV in a somewhat random state -- that is, with the various controls set to produce an image with best horizontal linearity & centering. I had also left in the .22 cap across the width coil. What kind of baseline is that? Perhaps it would make more sense to remove that .22 cap and center ALL of the pertinent controls, then repeat the rigamarole of subbing the cap and resistor values, looking for changes that make sense.
There are lots of variables in this equation. In addition to the horiz width and linearity adjusters, you have the horiz centering and horiz drive adjusters, all of which affect width and linearity to some extent. Not to mention the mechanical centering adjusters on the optical box.
Does anyone have a clear idea what changes you would expect to see on a perfectly-linear set when changing the value of this damper resistor (R86)?
Phil Nelson
|