Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #46  
Old 08-08-2014, 11:30 AM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
Quote:
Originally Posted by dtvmcdonald View Post
REALLY? I find that hard to believe! These are user controls.

McVoy did, however, say "all knobs"
I am about 99% sure that the horiz and vertical shafts were never fitted with knobs. If anybody here can prove otherwise, that would be welcomed information! The CTC-4 also has a similar concentric knurled shaft configuration in the pencil box, but in that case it is for vertical and tone controls.

jr
Reply With Quote
  #47  
Old 08-08-2014, 03:14 PM
Phil Nelson's Avatar
Phil Nelson Phil Nelson is offline
VideoKarma Member
 
Join Date: Jan 2006
Posts: 4,030
My CT-100 has just the knurled shafts, and this diagram seems to show them without knobs.



Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
Reply With Quote
  #48  
Old 08-08-2014, 07:00 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Well, Steve then must have been right ... it was all there.
Reply With Quote
  #49  
Old 08-08-2014, 08:43 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
I'm watching the Bear's game on the CT100.
From 4 feet away.

Other than the screen size, I don't see the complaints
people made in 1954. There is simply
nothing wrong with the picture, even brightness.

Is it that Videokarmites are more picky about adjustments?
Reply With Quote
  #50  
Old 08-08-2014, 10:40 PM
Phil Nelson's Avatar
Phil Nelson Phil Nelson is offline
VideoKarma Member
 
Join Date: Jan 2006
Posts: 4,030
The CT-100 can make an awfully nice picture. It's also complex and it requires careful setup. I wasn't watching color TV in 1954, but I wonder if many of those complaints were due to plain old misadjustment -- either because Grandpa started fiddling with controls or because the TV was never set up perfectly in the first place.

It looks like your CT-100 is dialed in very nicely, in any case. Impressive.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html
Reply With Quote
Audiokarma
  #51  
Old 08-08-2014, 11:59 PM
ChrisW6ATV's Avatar
ChrisW6ATV ChrisW6ATV is offline
Another CT-100 lives!
 
Join Date: Feb 2007
Location: Hayward, Cal. USA
Posts: 3,464
As bad as it sounds, I wonder if early complaints about color TV were just a variation of "flashing 12:00 syndrome"-people having one too many adjustments to handle and then losing everything as a result?
__________________
Chris

Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did."
Reply With Quote
  #52  
Old 08-09-2014, 08:47 AM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
There's a story of when Zenith engineers were shown the chassis, one of them commenting "Twenty-seven controls, each one making it worse!"
Reply With Quote
  #53  
Old 08-10-2014, 10:03 AM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
The set was working great on program material and most
test signals from the Digital Video Essentials DVD, and my own
test patterns, but not the horizontal and vertical color bars and
the red and magenta full 100% screens from the DVE DVD.

The bars showed incorrect luma for different bars and color changes
vertically across the horizontal bars.

This was traced after a VERY long session with a scope (and
the chassis in the set) looking at test points at the grids
of the first video amp, I and Q demodulators (removed from sockets),
and the three CRT grids.

The luma problem was a very slight misalignment of
the RF which I had simply not done (fixed), and the other is
(not fixed) a great sensitivity to the horizontal hold
when there is a saturated color right at the start of
a lot of horiziontal lines. Its got to be just right
so the burst sync timing is just right. This does not usually matter.
The waveform when I was aligning the burst stripper looked OK but not great.
I will have to study the circuit a lot before removing the chassis, which I will
have to do anyway to insert a UHF strip.

I was worried about signal overload, but tests show the set works
OK over a 66dB range from extreme noise and barely syncing up to
the normal power of my Blonder-Tongue modulator (which is set well below
max). At high powers one sees a few percent of nonlinearities, not
visible on pictures.
Reply With Quote
  #54  
Old 08-11-2014, 02:46 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
"27 adjustments and every one makes it worse". That's
a quote I read in an earlier thread, attributed to a Zenith guy.

Was it a complaint or a compliment? Did he mean 27 was too many
or that somebody had all of them perfect so that any change made it worse?

I see what he means though ... 27 is a lot. But I count exactly 69,
counting only one channel in the tuner. I adjusted the last one today,
the I-Q phase difference for the two synchronous detectors. This
make the red and green waveforms perfect and the blue within
a 10% resistor tolerance. Yellow is now yellow.

I'm theoretically done! The only thing left is to get Ch. 39 working
and replace a temporary resistor mess in the power supply.
Reply With Quote
  #55  
Old 08-11-2014, 03:56 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Oh! 69 is only the chassis. If you count all the tilts and pushes and
magnets on the CRT neck its 80. Add CRT rotation itself and its 81.
Reply With Quote
Audiokarma
  #56  
Old 08-13-2014, 01:58 AM
ChrisW6ATV's Avatar
ChrisW6ATV ChrisW6ATV is offline
Another CT-100 lives!
 
Join Date: Feb 2007
Location: Hayward, Cal. USA
Posts: 3,464
81 adjustments! You are making me think I should charge more, if I ever make a business out of restoring early color TV sets.
__________________
Chris

Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did."
Reply With Quote
  #57  
Old 08-13-2014, 08:02 AM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Charge by the hour!

Of course, the vast majority, once done, will last a long time.
If the remaining white peaking coils go, I don't think new ones
will change alignment.

Not to mention that this was a great learning experience for me ...
I'd never done a color TV setup since the late 60s,
and those were Heathkits. Doing it again would be faster, but not
easier. For a restoration you don't know whether a problem is a bad
part or adjustment until it is completely fixed, and there are
wrong leads ... like the modulator adjustment below. But the symptoms
it caused were also in part caused by wrong IF and RF alignment.
Two different problems, each of which required the same two different
fixes.

I found another adjustment that needed fixing for "blown whites",
wrong gamma of luma as color came near saturation,
and what looked like poor DC restoration, but
it was not on the TV, it was the video level
on my Blonder-Tongue BAVM modulators. If
set for auto level, which seems to work perfectly on
my Sony LCD monster, and is extremely subtle but there
on my 40's B&W sets, it was causing these problems.

I now have two channels to watch on NTSC: Ch. 6 for
OTA digital, and Ch. 10 for DVD. Hopefully tomorrow I
will have OTA Ch. 39 (HSN) for a few more months.
Reply With Quote
  #58  
Old 08-13-2014, 10:14 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Thanks to Dave A for the UHF tuner strip.

I was particularly impressed by the free shipping and the
return address on the box.

The strip had the worst case of sulfide attack I have ever seen.
Everything copper, silver, or brass was covered with a thick black fuzz.
This responded to no chemical attack alone so I used a half a box of
Q tips and Brasso, followed by lots of alcohol,
more Q tips, and then De-oxit.

The strip comes as Ch. 34 but changing to 39 is very easy:
tune the oscillator with a spectrum analyzer, tune in the station,
and tweek the RF adjustments for a good picture.

I'm now now looking at some woman with horrible splotches
of something white on her face ... this is a shopping channel.
But its real, analog NTSC, OTA TV. I think she is in need
of a sunburn remedy. That's probably what it is ... I have the sound off.
Reply With Quote
  #59  
Old 08-14-2014, 09:04 PM
Dave A's Avatar
Dave A Dave A is offline
VideoKarma Member
 
Join Date: Aug 2003
Location: SE Pennsylvania
Posts: 1,529
Doug, thanks for a tip of the rabbit ears for my contribution. The sulfide is not surprising given 60 years in a sealed box. Awaiting pix of the OTA. More parts are available from my donor chassis if needed. But not the fly...saving for my CT100. PM me.
__________________
“Once you eliminate the impossible...whatever remains, no matter how improbable, must be the truth." Sherlock Holmes.
Reply With Quote
  #60  
Old 08-18-2014, 10:27 PM
dtvmcdonald's Avatar
dtvmcdonald dtvmcdonald is offline
VideoKarma Member
 
Join Date: Nov 2012
Posts: 1,191
Here are the true OTA pictures of Channel 39. This is a 12.5 kW station
2.75 miles from me .. through my walls, with
a double bowtie antenna. The good picture is with a 16 dB
amplifier with a 0.5 dB nf and the noisy one is direct.
Attached Images
File Type: jpg _MG_4517b.jpg (78.6 KB, 81 views)
File Type: jpg _MG_4519b.jpg (82.5 KB, 64 views)
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 01:56 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.