RCA CTC-11 Chroma Alignment Issues

[old_tv_nut]

By happily working, do you mean that if you enable the horizontal you get a normal color picture? Please report exact details and not generalities.

Can you verify that your signal generator and RF modulator are working?
What is your scope bandwidth? If greater than 50 MHz, you can look directly at the inputs and outputs of your test equipment to see if the signals are there. If not, you can try connecting your demodulator probe to the output of the RF modulator to look for a signal.

Your sweep generator must be OK, since you used it to align the chroma bandpass. The RF modulator may need a stronger sweep signal than direct injection into the bandpass amplifier in step 1.

Possible pre-checks:
a) set up for step 1, get the response curve visible. Without changing anything else, add the 330 ohm / 4 mfd cap to pin 5 of V701. Does it change the curve shape or kill it entirely? If the latter, you may need more signal or the added RC network may be defective (e.g., the 4 uF cap is reverse polarity or defective).
b) set up for steps 2 and 3, but don't connect the 330 ohm / 4 uF. See if you have a response that then gets killed by the added RC.

[TonyP]

I dont get any display on the oscope for steps 2 or 3. Ive basically given up trying to inject the signal at the mixer grid. If you use the antenna terminals as the injection point, you set the tuner to channel 4 and use channel 4 pix carrier to inject into the rf modulator.. Ive tried it that was, and varied the bias on the tuner agc line and still get nothing.

Yes, my tv works fine if i connect it back up to the crt with the HV running.

I also tried using the Sencore Sm 158 speed aliner with its supplies probes and still get nothing. So its has to be my set up.

[old_tv_nut]

Can you set up for the IF/RF alignment and see a signal at the video detector?
You must have a mistake in your hookup somewhere, and you need to chase it down. You could try disconnecting the various bias connections one at a time, or connect only one at a time and see if something happens as you adjust the voltages.

To make sure you have it right, connect a voltmeter to each one in turn and check for polarity as well as voltage.

[TonyP]

I think I will forget my learning experiment. my eyes, color bar gen and vectorscope are saying its good enough. So i must have gotten the chroma curve at least close, just by aliging it by itself, without seeing the overall response curve to verify. i played with the chroma take off coil by watching the vectorscope pattern for max amplitude. just guessing on that one. I will probably break out the scope to see the waveforms on the crt grids, see how close to textbook they are. i need to do another set up as i never had good purity and one time i bumped the convergence assemby since the tv back is missiing. i need to make one.