help me ID this mystery GE roundy plz!
 

https://imgur.com/WvpxRTp

i know these px suck but I found this locally and I'm tempted to get it, but can find NOTHING about it, even with the MO# info from the back :o

https://imgur.com/HovvPWO
https://imgur.com/k54TvR3
https://imgur.com/wXwRzpB

what is it, who REALLY made it?

Philco? RCA?

if I cant find service info on it, it's just parts, I'd rater restore it.

any help welcome!
thanks!

SAMS lists a GE M939ACD:
https://www.samswebsite.com/en/photo...earch&s=Search

The back cover and front control layout resemble this GE in a Shango066 video, which he identified as a CTC-15 clone.

https://m.youtube.com/watch?v=kTesct_7uOA

thanks! I guess I was looking up the MO# in sections, not as a whole :/

that's why I got nothing :(

I have the Photofact in PDF if needed.

If you miss it, you're not missing much.
That thing's a dog. I scrapped one. The only good thing about it was the RCA 21FBP22 HI Lite CRT which was perfect!
The CRT was used in a much more deserving set, a Zenith 23NC**. The last roundie Zenith made.
The set isn't an RCA clone, a lot different.

Personally if I had more space I'd be interested in picking that set up... from what I understand they were sort of like a portacolor with a transformer power supply and traditional roundy sweep circuits.
The worst limiting factor of picture quality in the portacolor was the coarse dot pitch CRT...the roundys didn't have that limitation... There's a LOT LESS GE roundys surviving than RCA or Zenith so IMO they are worth preserving more than the RCA designed off brand clones.

The premium sets are nice to collect, but you can't fully appreciate a Dumont till you've experienced a Muntz.

Well, it's about 50 miles away from me, much closer than the stromberg carlson x-21 was, so I guess it's worth a try!

The GE Portacolors had two different CRTs: 11SP22 and the 11WP22. The early 11SP22 had the coarse dot pitch and the later 11WP22 had a much finer dot pitch - a much better picture. I owned one of each.

Actually, the GE KC and KD chassis is a glorified Portacolor!
The AC chassis set is a bit different using 6AU8's in the color circuit.
It's worth looking the schematic! IIRC, they made a rectangular set with a similar chassis.

Electronic M, your comment about not fully appreciating a DuMont until you have experienced a Muntz reminds me of my first high school job in a garage. A 1959 Rambler came in and I got the job to fix it. I groused a little bit about doing it and one of the other mechanics said I couldn't appreciate working on a Lincoln until I worked on a few Ramblers! He was right.

The CA chassis had a CTC15 clone look to it in many ways but GE revised some most circuits to use their tubes. i.e. 6BH11, 6FM7 etc.

I saw one of the CA or CB sets on an episode of "Mister Ed" when Wilbur brought home
a color TV one day, in an Italian Provincial IIRC.

I trained on a CX chassis, almost 50 years ago. It was RCA made, and seemed to be close to the CTC-12, with a few elements of the CTC-15. I think that was the last RCA chassis that they used.

well, I'm close to having it in my paws!

It's mine!

:banana:

https://imgur.com/6uhmLi7
very bad cataract
https://i.imgur.com/VuWhH0y.jpg
https://imgur.com/vSwF40g
https://imgur.com/Yty9iP5
reg cap is loose fitting, falls off easily.
https://imgur.com/N9dESJM

https://imgur.com/b1TBULo
https://imgur.com/rQgBKXh

now that is VERY stupid...
rather than replacing a bad socket, someone soldered the wire to the focus pin of the CRT? WTF? :thumbsdn:

https://imgur.com/58xIKOB
blue is a bit low, but the CRT is not dead, not as strong as the one in my CTC-16xl, but could be worse.
gonna let it sit a bit and wake up

Definitely needs a lot of work...
https://imgur.com/FYKd8kn

Screens at max for this, brightness ctl has almost no effect,
NO color, just causes green hue on screen. ( huge feeling of déjà vu here :o )

many dirty pots,

most tubes original.

screen should be much brighter given what my CRT tester showed me.

Set is most likely full of leaky caps.

The only thing that I wonder now is, what kind of cataract am I dealing with here, someone said that the CRT was a RCA type, but CRT so far has no markings or labels on it, so I'm not sure who made it.

It's an RCA style with that hard white moldy halo cataract other brands (like a NOS channel Master CRT I've got) had RCA style cataracts too.
Zenith types cataracts (also found in other brands like Sylvania) develop a gummy green halo.

RCA and Zenith evenly split about %85 of the TV market in the 50s-70's so people tend to name the 2 cataract types after the 2 brands each is most often found in.

The gummy ones can be cut with guitar string (my favorite method). All will be affected by heat (which can be dangerous) and some Will come off with water.

I'm still wondering what to do with this one,
as mentioned, it should be much brighter given how it tested on my tester, it almost but not quite as good testing as the one in my 16xl and it is VERY bright with bias at lowest setting and screens hardly turned up, so SOMETHING is not right here...
strangely this set has no CRT bias setting, and another odd thing I have seen that when shut off, there is a bright flash of raster seen on the screen as it powers down, IE screen is dark when on, shut off it gets brighter for a second as just as the sweep collapses, telling me there is most likely a bunch of electronic stuff to fix.

I wonder if I should try soaking this cataract, or would that even work on it?

but first things first, ( Hana Yori Dango ) , i need to finish the SC tv before I really start this one! :)

This is just pure speculation at this point, as I have only had the set on for about 30 min to evaluate it, and not even pulled the chassis yet.

I have no idea why they chose not to put the CRT bias in like RCA does.
https://i.imgur.com/6XruNV1.jpg
it's hard wired to the lowest setting via the 47k resistor R170, that is the area that in RCA sets that the bias switch is, that has dif resistors to change the bias, if R170 has gone up in value, it would no doubt cause a dim screen even with a good CRT.

once I start working on this, I will most likely replace that with a 50K 2 watt Pot, that will give me a way to adjust CRT bias on this thing.

What is the normal range of bias voltage? I would be cautious about using a pot if the voltage is high. Parts in this area might have to withstand momentary CRT arcs too.

Well, I can just go ahead a stick the proper switch in there and resistors to go with it, there IS a place for it in this chassis, it was just not put in, also gonna have to find a new CRT socket that is NOT overpriced. :/

looking a bit better!

https://imgur.com/eCBI6Us
color works!

I tacked a 75k ohm resistor across the 47k one to bring the bias up a bit, tha made things a bit brighter, for now.

I most likely wont have to resort to this after I go over things and replace out of tol caps and resistors.

CRT sockets removed from old brightners are usually cheap.

OK, What I think I'm gonna do with this CRT is, get a cheap kiddie pool, stick it in my shed, fill it with water, and a bit of ethylene glycol , take the CRT, remove the tape covering the sealed area, perhaps pick away some of the bad cataract with a spudger tool around the edge, and let it sit... and sit.

chassis removed...

it is a lot lighter than the CTC-16 is :o

https://i.imgur.com/efQcOV0.jpg
https://i.imgur.com/63XTKUJ.jpg

https://i.imgur.com/CdsulOR.jpg

ummm, that USED to be a thermistor... :tears:

but i doubt it's the reason alone for the diim screen,

The 2 main filter caps in the voltage doubler already seems dodgy , should be 2x 160 uf but they check 1 at 182uf and the other at 194uf,, seems unbalanced to me.
160uf is hard to get, gonna get a fresh pair of 180 uf.

These values are within 20% of nominal and should be just fine in that regard.

If they are the originals, the main thing to worry about is leakage/failure, but those capacitance measurements look OK.

Unfortunately, I have no real way to test the electrolytic capacitors for leakage. :(

I do have testers, a cheapy Mega328 LCR-T4 Transistor Tester, 2 DVMs that test caps, and a more pricey LCR meter, and all tell me generally the same thing within 3%-5% of each other when I test caps with them.

The Mega328 is the only one that shows any kind of leakage reading at all, but being powered from a 9v battery I don't put much faith in it for a accurate leak test for 200v+ caps.

And granted, when I DID power up and run this set, it was on for over 40 min, and all the electrolytic capacitors cans were still cool to the touch, so I guess that is a good sign that the are OK, not leaky.

And unlike my CTC-16XL, which had all the resistors replaced on the chroma/luminance PCB
everything in this one is all original, so I got to check it all. :o

https://imgur.com/RiRALCS

OK :D
Lets see how long this takes!
It is literally floating in the bathtub. :o

It SAYS GE on the tube but it still looks a lot like a RCA tube.
but unlike with my CTC-16XL, I had to remove the bracket around it cause it in the way if the safety glass.

Does it have a label with an EIA number?

Yes. E.I.A. 274.

EIA 274 was RCA.
http://www.thespeakershop.com/speake.../eiacodes.html

I recall a set with the CA chassis showing up in HS shop that looked in perfect condition, raster nice and sharp without a cateract - those days long ago, a roundie was a special set even then.

BUT the red gun was nearly dead or maybe another student zapped it with the tester-rejuv before I got to it. It sat there after that, waiting for a donor CRT. It really seemed worth the trouble based on every other measure.

No surprise that your CRT is RCA Hi-lite, being a year earlier than a CB-21" chassis GE that I worked on.

CB-21 was GE's last 21" round set, it had the original CRT and it was pretty decent emission like yours seems to be, the CRT label was well-hidden too. :D

IMHO, your CA will make better color than that '66 model did due to fact RCA circuits were used in the CA, but GE went full-on porta-color with the CB.

There was a FY-chassis for 1964, like the CTC-15 but I would jump for a CTC11 clone, the CW. I never saw one of those either.:sigh:

The cushioning material that was between the CRT and the retention band has deteriorated, (looks to be some kind of thin cork almost ).
And I know that when I put the thing back in, that having metal on glass is just about as bad as “crossing the streams” in Ghostbusters, so I wonder what would be a good substance to replace it with? That is not too costly?

Does the cushion go all around, or only a few points?

Arts n crafts stores often cary thin coark and or felt.

BTW I assume you mean mounting band instead of tension band. A mounting band will have tension adjusting bolts that allow you to easily and safely loosen the band and slip it off.
A tension band is mechanically tensioned in a non-adjustable way.

Mounting bands often have padding, but tension bands usually don't have any padding....also tension bands don't come off unless cut off and tension band CRTs usually implode after the band is cut off.

the padding was only on a few points,
https://imgur.com/wD1EKaZ

i tried to get a good pic of it... but SOMEONE got in the way, and changed the focal point of the shot at the last moment.

I would have left it on. but as you can see, that little tab on the bottom would not let the safety glass come off.

I guess if the original is cork, then that's the best.

Someone had to go and claim it as their own...
https://i.imgur.com/5hIaaam.jpg