RCA CTC 24 Vertical Output

[Electronic M]

First off turn the brightness down to the MINIMUM necessary to see the line. If you run it for more than a few seconds with that bright line you can burn the phosphor and be stuck with a permanent dark line across the middle of the screen when you get your vertical deflection working.

Vertical deflection failure (what has happened to your set) happens when a component fails in the vertical stage or you loose B+ to the vertical circuit. A quick-ish way to troubleshoot it is to run the set and measure the voltages on the pins of the vertical tube and compare them to the schematic.

The parts typically fail in the order most common to least: the 2-3 electrolytic capacitors (distinguished by being polarized) in the vertical, the vertical tube it's self, the rest of the vertical caps, circuit board ground solder joints(as well as tube socket solder joints and the sockets), resistors, the vertical transformer and or yoke. If there's no B+ the issue would be in the power supply instead of the vertical stage.

It's not possible to tell you which exact part has failed with the information you have provided so far... measurements and testing are needed to narrow the issue down.

Do you have the schematic/service manual for the set from Sam's or RCA?

Let me know if you need clarification.