I dunno. Considering the heirloom status of the TV, and unless the CRT is absolutely and equivocally proven weak and needing a brightener, i wouldn't do it. The pics Cary has posted of the CRT's display sure don't look like a weak CRT.
Symptoms of weak emission would include (from a cold start): coming on very dim with a 'silvery' or negative look, then gradually building up over several minutes to a brighter pic.

Yeah, the contrast on the below picture is excellent considering the room lights are on. The dark area's simply can't get any darker than the CRT face color when the set is turned off. The whites look very bright, and there's no visible retrace lines that I can see. IMO it's as good as it can get from an 19AP4. Turn the lights off and you can turn the brightness down accordingly. Kick back and enjoy. :thmbsp:

http://videokarma.org/attachment.php...4&d=1392130928

That picture looks wonderful! Nothing like seeing a good working DuMont and you are lucky to have one. Just get some help when moving the thing!

Nice job Cary! I'm new to TVs and you're giving me hope. Looks Great!

I just remembered although it may not apply in your case , the ion trap if not in the right position would cause less brightness , unsure if you ever checked it or not
mike

GOOD CALL on the ion trap. One of us geniuses shoulda thunk of it earlier.:nerd:

Howdy all,

Thanks for all the kudos on the DuMont! I appreciate it. Working on this set has certainly given me the confidence to do another, though it's more likely to be a tabletop model, unless something else falls into my lap out here in New Mexico.

Thanks for the tip on the ion trap. That is one of the first things I learned about to get the brightness up. The one on my set is just a magnet on a collar with a spring around it, no tightening mechanism, so it's also easy to accidentally knock it out of adjustment with just a touch...which I've done a couple times and then panicked as I wondered for a second why the picture got so dim suddenly.

I've taken a break from the DuMont to work on a few other projects. Doing some remodeling in the house and have to get the engine back in my Jeep Wrangler. It's been a "short block" sitting in the cargo area of our van for a month and a half now, and I've got an off-pavement trip coming up first week of April. AND, we've got nice weather right now...daytime temps in the 60's! Can't beat that for February, particularly considering the hammering the rest of the country is getting from the weather. I have to take advantage of it.

Back to the DuMont for a minute: I do have some NOS 1x2 rectifier tubes for the HV power supply in my mailbox, gonna pick them up this morn and see if it makes any difference when they are installed.

The only major issue I seem to be having with the DuMont right now is that I seem to have the picture well aligned, and in fact pretty good, but slightly off from the best sound alignment. The sound volume doesn't get very high at it's best when I adjust the sound IF cans, and there's plenty of "hum". I've gotten louder and clearer sound when the picture wasn't as good...makes me wonder if I don't have every single video IF can off by the same amount, so I get good picture, but they are too far from the range of the sound IF cans. There does seem to be some correlation, however slight, between picture and sound on this DuMont, even thought they are technically "split".

It will be something to tinker with in the next couple evenings as I finish up some other projects.

I'll certainly keep everyone updated, and thanks again for all the help and encouragement while I've been working on this DuMont! I'm very happy to have it back in the house for the first time in a decade, and operational for the first time in half a century!

Cary,
Unless somebody can advise otherwise, i would hafta say this regarding your sound tracking problem: The problem lies entirely with the sound IF strip, not the video. Any misalignment of the video strip would show up visually (as smearing, ringing, loss of fine detail etc.). Please resist any temptation to touch the vid cans any more. :)
I would try "walking" the sound cans a bit in one direction, and if tracking gets worse, 'walk' them in the other direction. 'Walking' each slug involves going only a tiny fraction of a turn at a time.

I will definitely try your suggestion. Thank you! I really would rather NOT have to fool with the video strip again if I can help it, at least until I have access to an oscilloscope and signal generator.

I don't know if I ever mentioned that it took about 8 HOURS, over two days, to get the picture to where it is now, strictly going by eye. I'm definitely not enthusiastic about doing that again.

you may have to do what I had to do to my Dumont , similar issue with the sound , so I hope I'm correct in what I'm about to say , if not someone correct me ... let the set run and warm up for about 10 minutes , tune the picture to where it looks best and then do what old coot said and go one by one with the sound alignments , eventually you should be able to get them to where the sound is the loudest where you are tuned to a good picture , working with the sound if alignments should be easier then doing the video ifs.

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

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.

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

Dumont 19AP4
 

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

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

Nos 19ap4
 

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.

When was that NOS 19AP4 made?

I know there are differences between tubes made in the 40's-50's, the phosphor is a uniform color, B&W tubes from the 60's-70's seem to have a different formula, if you look at them up close while on you can see yellow and bluish colors in the mix. I would assume it was done to make the image look brighter, like adding Bluing to wash makes it look whiter.

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.

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?

I'm still curious to see what it looks like in total darkness. Hold the camera right in front of the screen and photograph nothing but the image on the CRT (not even the green tuning eye).

Phil Nelson

White P-4 phosphor on early CRTs is actually a mixture of two different phosphors. One component is yellow and the other is blue. Combined in the correct ratio the mix produces a decent, fairly uniform white.
Sometimes I have observed, when re-installing a round P-4 CRT after work on the chassis, that orientation of the CRT is critical otherwise "blueish" areas of the CRT are illuminated. I suspect that the blue component of the P-4 phosphor ages more rapidly, and over time the used areas of the tube become "warmer" or more yellow. Likewise, I would postulate that a new P-4 CRT would very likely be bluer than a well used one.
jr

I think Phil is correct that it has to do with light balance in the room. Here's a couple shots(bad focus) of the 19AP4 in my Sentinel. Notice how when more of the back lite room is showing that the picture takes on the blueish tint. Somehow I always end up with a reflection of my GE clock on the screen.

http://i452.photobucket.com/albums/q...g?t=1393091979

http://i452.photobucket.com/albums/q...g?t=1393005792

That reminds me, I saw that effect when I reinstalled a CRT in my RCA T-100. What's causing those faint blue areas on opposite corners, I wondered? Then I realized that if I rotated the tube and reduced the height to normal, they would exactly match the areas never scanned by the electron beam. The center portion that had been scanned was warmer in color.

The color difference was subtle. It didn't really register in a photo unless I cranked up the contrast & brightness beyond normal levels, high enough to make retrace lines.

Phil Nelson

http://antiqueradio.org/art/RCAT-100PurpleCRT04.jpg

bluish 19AP$
 

sorry been busy, but No it's blue with my eye as compared to the old one, I know white balance all too well as I worked on in Broadcast Video Service and Working for the Packers in Replay.
I noticed this right away after I was just bored and replaced my old Slow warming 19ap4, I only did this because I had 2 N.O.S Tubes from the same person, not Rebuilt but NEW from Dumont but like 3 years newer or so..its a pain to replace, and you get used to it but I noticed the Blue right away.
here is a pic from the same set before and using the Exact DSLR Camera with the old original CRT .
I'll just have to get used to it, maybe for kicks I can push a RCA 630TS next to it and Take a few more pictures and compare.
but it seems that I remember someone Noting the same thing many years ago on this site, like 12 yrs ago or so. but my eye notices in person that its blueish for sure
Also maybe it does have to be Aged in like others have Said, I'll run it for hours and see. and I have found out that you can't blast away the Contrast or Brightness or you will get Retrace. I had pulled the whole chassis and checked it out, these Tubes for sure are not super Bright, it would be nice to find an Aluminized one, but those must be rare, I know they were made that way, I think Tung Sol shows it listed

I remember seeing B/W sets in the showrooms of department stores back in the day, and noticing the differences in the shading (color) of the CRT's on them.

We had a GE 19" set from around 1963 that was literally blue-white looking.

Maybe you have a 19AP4A or 19AP4B which have grey tinted/frosted faces ?

Wow. That is a georgeous TV.

Carl

OK here We go, 3 Pictures to amuse you :)
a 630ts to the left and the last picture notice the White cat.
sort of a pain to push and move all this.
I never looked to see if it had a Tinted face..I think they are a A version
one of these tubes was mounted in another set, but was not used so I am confused about the tint.
it's Noticeable in my eyes.
but Really a grey tinted face would Give a Blueish tint?
I should have posted a new thread about this instead of posting in Gary's thread, but didn't know it would go this far

What he said !

One good way to judge color is to stand back from the set in a dark room and see what the CRT is doing to illuminate the room. Is it bluish or greyish? The poor cameras are working overtime in a dark room trying to make something white...walls, lamps or the white Persian cat can all throw it off. Try taking a photo in a manual white balance set for cloudy...a higher kelvin temp closer to a CRT. This will fix the camera on a specific kelvin temp setting and you can then see what your CRT is doing in that neighborhood. It will also throw the surroundings very red as it tamps down the blue.

And on the sound IF tweek. Which is the best direction to adjust by ear? From the split to the end amp or backwards from the amp? And upper or lower adjustments first if the can has both? I did this with a Pilot TV-37 set to a good pix and had good luck going from the beginning to the amp.