Motorola roundie

[dtvmcdonald]

Originally Posted by old_tv_nut

What adjustment did you add?

I don't remember for sure. It was one of the six resistors from the I and Q
phase inverters to the three adders. I thought about which adjustment direction was missing. I thought again just now and come to the conclusion that it had to be one of the two resistors coming from the plate of the Q phase inverter.

Its no longer there. I had already replaced the six resistors with high stability
1% ones, and when I got the adjustments right I replaced the pot with
one of those fixed ones. As I said, it was within the stated 5% tolerance of those resistors.

If you look long enough at the list of adjustments, i.e. CRT screens, user color control, blue and green video gains, I gain, and relative demod phase, you come up with one degree of freedom too few for complete control.

As I have said innumerable times, this set has, for a single VHF channel,
81 adjustments. I adjusted every single one. The most critical are the two yoke tilts and two yoke lateral shift adjustments. Get these right and essentially perfect convergence is possible. Interestingly, when I replaced the CRT they did not need changing significantly ... the marks I had made were just fine.

Zenith's famous quip is wrong.