RCA 630TS sound problems, Round 2

[Phil Nelson]

I'm having a devil of a time getting a useful display on the oscilloscope, in hopes of aligning the sound IF on my RCA 630TS TV.

As background, I have recapped my EICO 324 signal generator and EICO 360 sweep generator (and fixed an output problem on the sweeper). Both work, as far as I can tell. At least they put out signals that I can display on the scope.

The alignment instructions tell you to connect the sweep generator output to the 2nd sound IF amplifier (V105) grid and to connect the scope to the 3rd sound IF grid return (terminal A T112) in series with a 33K ohm isolating resistor.

Here's part of the schematic for those who are eagerly following along :-)

http://antiqueradio.org/art/temp/RCA630TSSchematic1.gif

Here's the setup page from the EICO 360 sweeper manual:

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

I am using this setup.

- The output of the signal generator (set to 21.25 mhz sound IF frequency) is fed to the external marker input of the sweep generator.

- The 60hz sweep output of the sweep generator is fed to the horizontal input of the oscilloscope.

- The RF output of the sweep generator is fed to the 1st TV connection point given in the instructions.

- The oscilloscope vertical input is connected to 2nd TV connection point given in the instructions.

According to the manual, I should see a nice textbook waveform with a little marker pip. What I'm actually seeing is a pair of fuzzy horizontal lines on the scope. Twiddling the scope controls doesn't change the display. Twiddling the generator (either one) controls doesn't change the display, except that turning the 60hz phasing control on the sweep generator can either bring the horizontal lines together vertically, or move them back apart.

I am not a scope expert. No doubt I'm doing something stupid . . . but what?