The Family DuMont

[Phil Nelson]

This kind of divergence is common with "split sound" TVs like this, where the sound signal is picked off fairly early and the audio section has its own series of IF amplifiers, in parallel to the video IF amplifiers, so to speak. (An alternative, slightly more modern design is to pick off the audio signal farther downstream, after the IF amplification has been performed.)

Look carefully at the schematic and your manual's sound alignment instructions, and you should be able to do what old_coot88 says: gently nudge the audio IF alignment to match up with your current video IF alignment, so that they both tune in together. I think you will find it considerably easier than video alignment.

Phil Nelson

[old_coot88]

Cary,
You gotta realize that the normal video IF bandpass is extremely wide, and the individual cans are actually stagger-tuned to different frequencies within that band.
Whereas the sound IF is tuned to only *one* single frequency and is extremely narrow compared to the vid IF.

This is why no amount of tweaking the vids is gonna shift their tracking 'toward' the sound.

Whereas shifting the sound IF centerpoint relative to the vid will change tracking.

[kramden66]

here are some pics of the sister to your Dumont , the ra-109

[wiseguy]

on this RA-109 I have please look at the crappy cell phone pics that I took while running out the door, . I though it was my eyes but even my cell phone shows this.
since Everyone is talking about Dumonts and 19AP4.
is there something different about the Phosphors in these tubes?
its perfectly Focused, its just a crappy cell phone picture, and the camera white Balance is fine,
I will take another pic with my Nikon DSLR later afterwork. but for sure with my eyes its Bluish

[Phil Nelson]

One of my cameras makes B/W screens look very bluish. I think some of it has to do with shooting under comparatively yellowish indoor lights. The camera does some kind of color average (is that the right term?) with the room as a whole and gets the colors right for the cabinet, drapes, etc, but the screen comes out too blue. It's so blue that, for photos I want to use on my website, I sometimes cut out the screen portion and convert that to greyscale so that it doesn't look ridiculous. This effect is true of all my B/W sets, with various CRTs; they all display shades of grey to my eyes but the camera turns them weirdly blue.

Try turning out all of the room lights and taking a photo of only the screen. Then turn on the room lights, photograph again, and compare blueness of the screen in both shots.

I'm not saying that phosphors don't have different colors, only that I've seen this very obvious effect when shooting photos under warm indoor lights.

Phil "not a serious photographer" Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[wiseguy]

This is a afternoon shot with a Nikon DSLR this time
This is a NOS 19AP4, guess I should have left the sort of weak one in.

[CaryLee]

Originally Posted by wiseguy

This is a afternoon shot with a Nikon DSLR this time
This is a NOS 19AP4, guess I should have left the sort of weak one in.

I don't have much to add having little experience with various CRT's. It does look kind of bluish in the photo, but it is a good clear picture. I wonder if you would notice the tint if you didn't have anything to compare to?

Do CRT's have a "break in period" when they are new? Might it settle down a bit with use?

[CaryLee]

Originally Posted by kramden66

here are some pics of the sister to your Dumont , the ra-109

Wow! That's a rock-solid, dead on, straight and uniform picture!

I still have a couple issues with the adjustment on mine..sometimes people's foreheads and hairdos seem to get a bit bigger towards the top of the screen.

I tried my test pattern disk in a newer DVD player and it worked. It won't play in the older dvd player I have hooked up to the DuMont. Now I have to decide if I want to go through the hassle of unhooking the newer DVD..it's pretty tough to get to the wires, and there's a 30 gallon aquarium on one end of the hutch it is in..so easily moving the furniture to get to the wires in not an option. I might have to commandeer my son's Xbox 360 temporarily to use as a DVD player...if IT will play the disk.