Potential new project!! Silvertone Roundie - Page 3 - Videokarma.org TV - Video

DaveWM · #1 08-10-2011, 08:34 AM

most of time heating the wire is not required, just warm the CRT face on in the sun on a hot day and use a strong steel wire to pull thur the adhesive. I use a couple large wood dowels to wrap SS .015 wire around them for hand holds, then you sort of saw thru. the adhesive should be like thick gel.

Personally if its just a very light green stain around the edges I would not be in a hurry to remove it. The CRT's are bulky and not easy to handle, and if you remove all the yoke/conv/purity gear you will have to reset it all up. Some ohter things, be very careful when removing the CRT socket and the yoke, you dont want to stress the CRT pin base, the glue that holds it on is fragile.

zenith2134 · #2 08-20-2011, 12:49 PM

You guys always manage to coax such amazing pictures out of these roundies. I still need to find one, that'd be a fun project!

Nice save on the Silvertone. Wasn't Silvertone the one that had the 'Chromix' switch which IIRC did something to the chroma demodulating circuitry?

maxhifi · #3 08-10-2011, 09:48 AM

I have to say, I am a little bit afraid of handling the CRT that way. Sooner or later though I will feel the urge to make it perfect. I have to be 100% confident in my ability to set up a CRT from scratch though, and I'm not there yet.

I will also probably wait until I have a spare CRT before I do something which could possibly ruin this one or its lens - that said, I am pretty sure that sooner or later it's going to happen.

DaveWM · #4 08-10-2011, 09:55 AM

thats what I did, practice on one if you can to get the feel of it. My first one was a rectangle that had a very weak gun. There is a big diff in the green vs white, the white is VERY hard but not nasty, the green is gooey and makes a big mess, but cuts easy.

Electronic M · #5 08-10-2011, 11:59 AM

When I did this video in this thread http://www.videokarma.org/showthread.php?t=251762 I had all the neck hardware in place. I merely disconnected the yoke cable, CRT base, HV cable, and unpluged and unbolted the convergence board. All before unmounting the CRT. I then merely lifted and set the CRT in the bucket so the convergence board was in the bottom. After I finished and remounted the CRT I got the exact same picture quality (yes the purity and convergence were still as I had them) as before I pulled the CRT.
With how well leaving the neck hardware on worked I plan to do that on all future tubes that I decat.

Tom C.

DaveWM · #6 08-10-2011, 12:48 PM

Yes leaving the parts attached is an option, and will save on setup labor. Just be careful, more stuff dangling from the CRT (wireing from yoke and convegence coils). Prob be a good idea to secure that stuff with some tape or zip ties so it does not get in the way when moving the CRT around.

marty59 · #7 08-12-2011, 08:49 AM

Quote:

Originally Posted by DaveWM

Yes leaving the parts attached is an option, and will save on setup labor. Just be careful, more stuff dangling from the CRT (wireing from yoke and convegence coils). Prob be a good idea to secure that stuff with some tape or zip ties so it does not get in the way when moving the CRT around.

Heck, as long as you measure and take notes you should be able to get everything back to where it was. I'd hate the risk of breaking something or having wires come loose in the process. A digital camera and a sharpie pen are your friends! Plus, you get the fun of sharpening up your convergence skills!

maxhifi · #8 08-11-2011, 11:42 PM

Well - I'm sure getting into this hobby... went back today for the parts chassis, and came home with the parts chassis for this set, as well as a zenith color console chassis, an Electrohome B&W chassis, and an Admiral color console chassis I left there, couldn't fit in the car.

Also got a B&K high voltage probe, and a B&K 415, with cables. He's going to look for the manual and give it to me when I return for the Admiral chassis.

The parts chassis had a good 6BK4 plate cap and wire.... cured the problem with arcing right away.

The Zenith, Admiral, and Electrohome are fairly complete, and flybacks look good... will post models on the classified section here after I pick up the Admiral they're no use to me.

maxhifi · #9 08-13-2011, 03:46 PM

Well, speaking of convergence skills, I did a full setup on the Silvertone (my first ever attempt to converge a direct view CRT TV). I thought the picture was great to begin with, but after a few hours noticed the reds looked pinkish in one corner.

Did a purity adjustment, followed by full convergence. Purity is awesome now, nice beautiful even red everywhere except the cataract.

I got the convergence very very close, but either the blue "lateral" magnet is too weak (well, I tried two of them), or, the blue lateral and the convergence coil assembly is not positioned properly.

Convergence is about perfect all over the screen, except blue is maybe 0.5mm too far to the right, all over, and the adjustment is just outside the lateral magnet's range. Since I tried two magnets, I am starting to think the whole assembly is in the wrong position.

Does anyone have a photo of the coils and magnets on the back of a CTC15 pic tube, in their correct positions?

old_coot88 · #10 08-13-2011, 04:45 PM

Quote:

Originally Posted by maxhifi

Does anyone have a photo of the coils and magnets on the back of a CTC15 pic tube, in their correct positions?

Is the BL magnet centered directly over the 'pole piece' on the blue gun? That's a squarish little sheet metal thingy spotwelded on top the gun inside the CRT.
oc

maxhifi · #11 08-13-2011, 06:00 PM

Much better!

Everything was half an inch too far back on the CRT neck - BL magnet, Purity rings, and Conv. coils. I wasn't sure what was supposed to be the reference point.

I set it up properly, then re-did purity, then tried convergence a second time, with the result attached.

Electronic M · #12 08-13-2011, 06:54 PM

I tend to tweak the position of any neck hardware with little reguard for it's exact proper position. After all what matters is getting the best purity, convergence, etc.

You did quite well by the way.

Tom C.

sampson159 · #13 08-14-2011, 09:10 AM

looks extremely good!i wouldnt touch a thing as you are on the money.this was my job specifically back in the shop days.the other techs wanted no part of it,so it was my baby.from your picture,i couldnt have done any better.maybe not have done as well!

maxhifi · #14 08-14-2011, 11:27 AM

I think I am fortunate with this chassis, it has a ton of adjustments, and the demountable convergence board can be accessed from the front. Convergence sure was easier than I expected, although it did take me a while.

Purity is tricky though... mainly because the tube is so deep that it's difficult to adjust it and see the screen at the same time. I need to read up a bit about what the purity rings actually do to the electron beams - the function of the other magnets is fairly obvious, but the how the purity rings actually work seem a bit elusive to me.

old_coot88 · #15 08-14-2011, 12:16 PM

Quote:

Originally Posted by maxhifi

I think I am fortunate with this chassis, it has a ton of adjustments, and the demountable convergence board can be accessed from the front. Convergence sure was easier than I expected, although it did take me a while.

Purity is tricky though... mainly because the tube is so deep that it's difficult to adjust it and see the screen at the same time. I need to read up a bit about what the purity rings actually do to the electron beams - the function of the other magnets is fairly obvious, but the how the purity rings actually work seem a bit elusive to me.

After a thorough degaussing here's how to set up purity on roundies, and this is from the original RCA factory procedure. It's worth bookmarking for future referance. (It applies to RCA clones of course, as well as Zenith.)
Set the service switch for blank raster and turn blue and green screens all the way down and red screen up. Loosen the yoke clamp and slide the yoke as far back as it will go. Use the purity rings to put the red blob as close to center as possible. Slide the yoke forward, watching to see where the best red purity occurs. This is counterintuitive, because normally the "sweet spot" will occur 1/2 to 1/4 inch before the yoke is fully seated against the CRT bell. Clamp the yoke at that point.
On rectangular sets up through the CTC-25 etc., the procedure is the same except the 'sweet spot' normally occurs about 1/4 to 1/8 inch before the yoke is fully seated.
oc