Quote:
Originally Posted by Chris K
So I should use the tuner to get good sound and then get the best sound by adjusting the RF unit to get the sound to optimal?
Then move down the video IF and adjust to get the picture optimal and coordinated with the sound? |
I would suggest first tune the rf oscillator to get best sound, return the first IF adjustment close to where it was and then assess the situation.
If their was evidence of repair work in the past, someone may have tweaked the IF. You may be lucky and find the response not bad and only some minor tweaking is required. But after 75 years, it would be useful going over the alignment.
Do you have an accurate rf frequency generator? I have used mine to determine if the discriminator zero setting is still on frequency and the traps are still set to frequency. Checking the discriminator zero cand be done with an unmodulated rf source set to the sound IF frequency loosely coupled to the first Sound IF stage.
Tune the generator back and forth across the manufacturers setting and either use your ear or a VTVM to find the null. Unless it has been monkeyed with in the past it should be close to spot on. Next loosely couple the generator modulated with say 400Hz to the rf mixer and tune the generators across the trap frequencies and see if you can see the dips on the crt screen. That is my preliminary test with these sets.
A couple of years ago when I resuscitated my 1947 RCA 72TCS, I did the same and found the alignment pretty close. I nevertheless did a full alignment to obtain the manufacturer's response. The RCA is a cheaper set with only three video IF stages and with an overall video bandwidth of only 3MHz, yields pretty good pictures. Yours with four stages should be better.