Quote:
Originally Posted by dtvmcdonald
Why not try a 3.58 MHZ signal from a signal generator? disconnect the crystal, feed the signal from the generator to the no-longer oscillator's grid and look on the scope at the two outputs of the
output transformer.
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OK, I tried this (substituting the 3.58-mc signal from the VA62A analyzer at the grid of the chroma reference oscillator tube). It looks as if T115, the CW transformer, can pass the signal and be peaked.
In that photo, the scope was connected to terminal F on T115. By turning the bottom adjuster of T115, I could increase the amplitude up to a point, beyond which it fell off again. When I moved the probe to terminal D, the waveform looked about the same, although I didn't try the top adjuster.
None of which helps me figure out why the oscillator doesn't oscillate, but I'm taking it as evidence that T115 is operational, anyhow.
I had to move the adjuster quite a long way from its original position to find the peak, but perhaps that isn't surprising, given that many of the components attached to T115 have been replaced.
Phil Nelson