Quote:
Originally Posted by SwizzyMan
OK. Where is the reactance grid and how do I ground it?
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Look at the description of Step 4 and the photo on page 36 of the RCA factory manual (I provided a link to that manual above). Step 4 tells you to ground the reactance tube input at the junction of C726/R743. If you look at the schematic on page 50 of the manual, find that junction and then follow the connection to pin 9 of V707-A, the 6U8A reactance control tube. Grounding the point shown in the manual effectively grounds the input grid of the reactance tube.
Step 4 also tells you to ground terminal D of transformer T701, also shown in the photo on page 36.
You can ground these points with two clip leads -- wires with an alligator clip on each end.
After grounding those two points, you can try (gently!) adjusting the reactance coil L704, also shown in the photo. If you don't have a plastic screwdriver, you can make a tiny adjustment using a metal screwdriver and then pull it out and hold it at least a foot away from the coil. See any difference? You want to slow the rolling of the color bars. This is a cowboy way to do it -- the bars may go nuts when the screwdriver is in the coil and your body capacitance affects the circuit. But when you pull it out and step back, you should be able to tell if your adjustment made any difference.
If adjusting in one direction makes the rolling faster, try adjusting in the opposite direction. The ideal is for the bars to be static -- floating without any roll -- but a very slow roll is better than a fast one.
If you get the bars to stop rolling, remove the temporary ground connections and see what the picture looks like.
If the cowboy adjustment doesn't work, I would do careful checks of resistances and voltages on V707, which acts as both the oscillator and the reactance tube.
Phil Nelson