View Full Version : CT-100 works! (but the zener mod didn't...)


David Roper
08-28-2016, 04:32 PM
Thanks to Steve K, B8003192 has joined the still-too-short list of operational CT-100s. The 15G has a weak red gun, but for some reason these phone pics make it seem much moreso than it looks in person. Despite appearances, the green gun is only marginally stronger than the red one! Fortunately, there is plenty of brightness to spare. I haven't yet attempted adjustment for color balance--or in fact any of the setup procedures whatsoever. What you see is just from raw futzing after re-installing the chassis.

I have a spare chassis which provided a few 6AN8s and a vertical centering pot. Little else other than caps and inductors was needed. This set retains its original flyback and vertical convergence transformer, not to mention the shouldered HOT, which is an awesome thing for a color TV set to have. :)

I'm at the moment unable to share video, which is a shame because I can't wait to show how rock-solid the picture is with even the most extreme rapid changes in content. The regulation is unbothered and the focus constant. The last bit is important, as I had originally intended for this set to have the focus modification that Tom Albrecht invented (http://videokarma.org/showpost.php?p=3093442&postcount=142) for his own set. Unfortunately, Steve K reported that once implemented, the focus pot no longer worked. He speculated the reason might have something to do with Tom's set using a tripler vs. a flyback. I'm curious if anybody else tried that mod and what the result was.

dtvmcdonald
08-28-2016, 04:57 PM
my CT-100 has a Zener focus mod, but it is trivial: I just measured
the correct focus voltage and replaced the resistor chain form
the bottom of the focus control to ground with a chain of Zeners
selected so that the control would be about 1/4 up.

Electronic M
08-28-2016, 08:58 PM
Congratulations on getting it going! Never thought I'd see One Punch Man on a Ct-100...Though I watched it on Zenith's first SS TV model not long ago.

Steve K
08-29-2016, 10:23 PM
Hey David:

While you're waiting to show some more pictures of your CT-100 I thought that I would post a few screen shots while your chassis was connected to my CRT. Glad to hear that it survived the trip back to Michigan!

Steve

Steve D.
08-30-2016, 08:36 PM
David,

So happy your goal of owning a working CT-100 has been realized. A tip of the hat to Steve K. for working his magic in restoring that set. I'm including the 1st photo of that original condition CT-100 I received from former owner Rosalie Parr. Glad it all finally came together for you.

-Steve D.

Electronic M
08-30-2016, 10:02 PM
I'm surprised someone so confident in their tech knowledge actually let someone else do the resto of such an interesting set for them.

David Roper
08-31-2016, 06:50 AM
Hey David:

While you're waiting to show some more pictures of your CT-100 I thought that I would post a few screen shots while your chassis was connected to my CRT. Glad to hear that it survived the trip back to Michigan!

Steve

If I never have to drive through Chicago on a Friday night again it will be too soon! But seeing the screen light up for the first time in 48 years (going by the last repair tag) more than made up for the drive home. Thanks again for bringing it back to life!

David,

So happy your goal of owning a working CT-100 has been realized. A tip of the hat to Steve K. for working his magic in restoring that set. I'm including the 1st photo of that original condition CT-100 I received from former owner Rosalie Parr. Glad it all finally came together for you.

-Steve D.

I owe you a huge debt of gratitude for passing that tip along. I have had nothing but extraordinary luck with this set--and that includes getting my hands on it in the first place, a chance I never would have had if it weren't for you.

I'm surprised someone so confident in their tech knowledge actually let someone else do the resto of such an interesting set for them.

Are you? Confidence is important, but so is knowing one's limitations and being willing to work within those limitations. It's true that not much of the work bringing the set back t life was done by me, but it was more work than you've done on the set you haven't got.

Electronic M
08-31-2016, 07:59 AM
Every set I own that works, does because I did it myself. What I don't own (I do have the next RCA color chassis after it) I only lack because my former poor college student self could not afford to pay the prices set by well healed old-timers. With a good job now it is only a matter of time before I have a collection of early color (among other things) up there with those that specialize in it.
You will never grow as a tech if you never push your limitations.

dtvmcdonald
08-31-2016, 11:14 AM
Are you? Confidence is important, but so is knowing one's limitations and being willing to work within those limitations. It's true that not much of the work bringing the set back t life was done by me, but it was more work than you've done on the set you haven't got.

I agree completely ... and its important to pick the right things to learn on.
I have great confidence on anything tube. But on solid state stuff, if differs.

I have great confidence on scientific solid state stuff. It generally has single
digital power supplies, and an analog +- 12 or 15 volt dual tracking supply. AND ... its generally not filled with unobtanium parts nor fragile
circuit boards. High voltage supplies are always quite separate. And the
big good point is that global feedback is generally very simple and
easy to understand. Luckily I never had a 3000+ volt supply go bad.


Not so for my new Indextron ... a nightmare of strange interconnected supplies,
with feedback between them, un-understandable feedback in both
H/V sync and index systems, and unobtanium parts galore. And the
killer -- several unobtanium coils and tranfsormers in the the
area that needs to be ultrasonic washed to get off the corrosive goo.

So I sent it to the experienced specialist.

etype2
08-31-2016, 12:11 PM
Not so for my new Indextron ... a nightmare of strange interconnected supplies,
with feedback between them, un-understandable feedback in both
H/V sync and index systems, and unobtanium parts galore. And the
killer -- several unobtanium coils and tranfsormers in the the
area that needs to be ultrasonic washed to get off the corrosive goo.

So I sent it to the experienced specialist.


Congratulations on obtaining your new Indextron. By the above quote, I am assuming you sent your Indextron to Andy. He did a great job on my two Indextrons. It is usually bad leaking caps problems with Indextrons. They were defective in nearly all Indextrons. It's been 6 and 5 years since Andy's repair and they both look as good as ever.

I see no problem with having someone help when in doubt or inexperienced. You can learn from others by asking questions on what they did and how they did it.

init4fun
09-02-2016, 10:13 AM
I'm surprised someone so confident in their tech knowledge actually let someone else do the resto of such an interesting set for them.

Are you? Confidence is important, but so is knowing one's limitations and being willing to work within those limitations. It's true that not much of the work bringing the set back t life was done by me, but it was more work than you've done on the set you haven't got.

It is obvious from the tone of these posts that there is prior friction between you two gents , and , in an interesting way you both do have valid points . David's point of not sharpening the skills on a rare set is well advised , as too is Tom's point of challenging oneself to the unknown as a path to further knowledge . The dividing line being , of course , how much risk is one willing to take with the first time restoration of a rare item , and to the person involved how much of the want of this item involves wanting to dive into restoring it VS having it in the collection as a restored rarity. Each person being different of course it's that person's choice and as long as the end result is another working CT-100 that's the bottom line . It kinda reminds me of two guys I know , one of them is a professional mechanic and on his off time fixes each and every thing on his car and won't pay a dime to have anyone else do the work . That guy hates car racing . The other guy is a car racing nut , he can tell you the technical stats of each of the racecars , really knows the specs of the cars inside and out and the stats of all the drivers too , but is too unsure of the handling of the actual tools to change the oil in his pickup truck by himself . Those two are forever zinging each other about who is the "real car guy" and to me they're both "real" car nuts , just with different things they want out of the hobby .

:thmbsp: Bottom line , It's great that another CT-100 lives !

benman94
09-02-2016, 10:41 AM
I've farmed out early color sets to other restorers simply because I've come to loathe working on early color. In turn, I've worked on more than a few brute-force HV sets for people too afraid (and for good reason) to work on them. At the end of the day it doesn't matter who the hell is doing the restoration work, so long as everyone is happy with the end result.
Your CT-100 is looking good Dave! :tresbon: Perhaps the red gun will wake up a bit with more use. I had a CTC-9 or 10 with a dead looking green gun that sprang back to life after 4 or 5 hours of use.

miniman82
09-03-2016, 05:24 AM
This set retains its original vertical convergence transformer

You may live to regret not getting the repro from John, they all fail sooner or later. Consider it a maintenance item, when it goes it takes the focus pot with it and I promise you'll never find another- I've tried.

David Roper
09-03-2016, 11:58 AM
You may live to regret not getting the repro from John, they all fail sooner or later. Consider it a maintenance item, when it goes it takes the focus pot with it and I promise you'll never find another- I've tried.


My spare chassis still has those parts. On-off switch too.


I've farmed out early color sets to other restorers simply because I've come to loathe working on early color. In turn, I've worked on more than a few brute-force HV sets for people too afraid (and for good reason) to work on them. At the end of the day it doesn't matter who the hell is doing the restoration work, so long as everyone is happy with the end result.
Your CT-100 is looking good Dave! :tresbon: Perhaps the red gun will wake up a bit with more use. I had a CTC-9 or 10 with a dead looking green gun that sprang back to life after 4 or 5 hours of use.

Good to hear from you! As you know, I have another, arguably even more "interesting" 1954 color set to restore when I'm ready. I've been encouraged to go for it under the logic that once you've been successful in restoring three B&W sets, you're ready for a color set--except it's like working on all three at once. So by rights I guess I should have completed three or four color restorations by now. On the other hand, I know you came by your loathing honestly. I think the as-found condition of each set was the factor that determined the CT-100 would be left to expert hands while I would (eventually) tackle the 205 myself.

As for the red gun waking up, yes! In fact the whole thing was sleepy. The first two times the tube was powered on it took every bit of twenty minutes to warm up, with almost nothing visible on the screen for the first five; now it's almost ready in five. Although I was not able to play a DVD of test slides that I burned for the purpose of a full setup, I still made wonderful progress with color balance last night.

benman94
09-03-2016, 12:10 PM
Your red gun is absolutely fine. The first and third shots show plenty of red and look pretty close to what I'd call watchable. :thmbsp:

The CT-100 I had, that's now John Estep's, had a green gun that would take a touch longer to wake up than the other two guns. By the time I sold it to John, the green gun was coming to life right in step with the red and blue. I'm guessing in both of our cases, very mild cathode poisoning from ~60 years of non-use was to blame.

Steve D.
09-03-2016, 12:53 PM
David,

Looking better. Just needs some basic degaussing/purity set up first, setting screen controls ect. and then tackling the convergence. Setup can be a test of your patience, but well worth taking your time with it. Your SAM'S is a good guide for the set up sequence. Also, Phil Nelson posted RCA's CT-100 service manual on line. Purity starts on page 39 and continues into the convergence procedure: http://antiqueradio.org/art/RCA%20CT-100%20Service%20Clinic%20Manual.pdf. You probably have all this info.

-Steve D.

David Roper
09-08-2016, 05:39 AM
I did the setup. Here's a video (https://youtu.be/EughPokimVw) of how it looks now.

Steve D.
09-08-2016, 11:08 AM
I did the setup. Here's a video (https://youtu.be/EughPokimVw) of how it looks now.

Wow! Red, blue & green acres all in the proper place. Outstanding job w/the set up.:thmbsp:

-Steve D.

Phil Nelson
09-08-2016, 02:31 PM
Excellent! It's great to see another CT-100 back in action.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html