RCA 630TS sound problems

[John Folsom]

Phil, you can operate the set without the CRT, no problem. I like to tuck the HV lead inside a small glass or jar to keep it out of trouble. You can disable the horizontal sweep, but this will remove a considerable load from the power supply, and cause it to run high, which can change the operating point of you IFs and change the alignment.

[Phil Nelson]

OK, maybe y'all can help me interpret what I'm seeing.

The manual section "Retouching Picture IF" required less setup than other video alignment sections, so I started with that. I followed directions, setting the picture IF grid bias to -3 volts and connecting the sweep generator output to the antenna terminals. I connected my signal generator, set to the picture IF marker frequency of 25.75 mhz, to the external marker input of the sweep generator. They also want you to insert a second marker at 22.3 mhz, but I don't have that many signal generators in the house.

The instructions said to connect the oscilloscope across the picture detector load resistor. Perhaps they mean R136, which appears to be wrapped in a little coil (peaking coil?). Anyhow, I didn't get a coherent display with that connection, so I connected the scope probe to the far side of that resistor/coil (i.e., the junction of L187, R136 and C138), which did give a display.

The first photo shows the display with the sweep generator connected and sweep width set to 0. (The signal generator is not connected at this point.)

http://antiqueradio.org/art/temp/RCA630TS24.jpg

The second photo shows that I can get a sort-of shouldery waveform by turning the sweep width way up (from 0 to around 24).

http://antiqueradio.org/art/temp/RCA630TS25.jpg

The third photo shows the waveform after I connect the signal generator (set to picture IF frequency) to the sweep generator, with the signal generator output set pretty low.

http://antiqueradio.org/art/temp/RCA630TS26.jpg

The last photo shows that I can increase the size of the marker blob (I wouldn't call it a pip!) by increasing the output of the signal generator.

http://antiqueradio.org/art/temp/RCA630TS27.jpg

So . . . is it worth trying to align the sound IF with this gear? Or should I just throw in the towel and buy a new sweep generator?