Zenith 14DC16 Colour question/problem

[ctc17]

We can get a console on the roof of your mustang, I have rope. Some of those table tops are on my panic checklist and are going with me to the grave.

Which type do you like? I can keep an eye out.

[maxhifi]

Now that is funny, going down the interstate at 75 or 80 in the rain, with a console TV teetering on top of the mustang's tiny roof! I should mention I live in Canada! It's a couple days drive to get as far south as you are, but has made a fun trip in the past.

Best type for me is early 70s medium sized portable, 16 - 20 inch, hybrid or all tube. Brand would be Zenith or RCA, but I'm not looking for anything specific. A power transformer would be nice, but sure not essential. Emphasis on (potential for) picture quality above other factors.

[maxhifi]

New divider came today - installed it. Focus problem instantly fixed.

Used recently acquired knowledge to check purity and convergence. Convergence was okay, purity was awful! Colours actually adjusted to NTSC now, finally accomplishing the original intent of this thread. Thanks to all who contributed.

[maxhifi]

It's only been a month and a half?

Color has lately become intermittent

It comes on and off, with a gentle tap to the side of the set. Tried to sub all tubes related to color, and even the ones in the tuner and IF, to no effect. Color killer doesn't make a difference either.

Inspected for wires shorting and noticed nothing. Burst xtal? Sometimes even a tap to the coffee table will bring color back, or kill it, if it is working.

[maxhifi]

OK never mind, I tried to sub the crystal with one from an Admiral console chassis - really messed up the colour, but it stayed on, red was blue, everything totally wrong. Tried to adjust A24 to dial it in without any luck.

Tacked in the xtal from an old Zenith console, and success, color is back, looks great, and no amount of tapping can disturb it. Don't have to hear my daughter asking why the people look grey again.

[Electronic M]

After reading this I'm contemplating swaping out the crystal on my 71' Zenith hybrid. That darn thing has been slow to warm up it's color circuits for several years now, and has had problems with it's focus divider that at times have coincided in ways that have made me wonder if the two are related. I may change the divider soon so if the color issues continue after that I'll try other crystals while it is "on the bench".

[maxhifi]

Originally Posted by Electronic M

After reading this I'm contemplating swaping out the crystal on my 71' Zenith hybrid. That darn thing has been slow to warm up it's color circuits for several years now, and has had problems with it's focus divider that at times have coincided in ways that have made me wonder if the two are related. I may change the divider soon so if the color issues continue after that I'll try other crystals while it is "on the bench".

Well, it wasn't the crystal Sorry for late reply.
It's gone back to intermittent

I think it's something temperature related. It has NEVER lost color in the first 10 minutes of being on, and never with the cover off.

No time to dig into it right now, been messing patching a crack in my foundation before snow on the ground - also been working on new project, '69 Ford F-250 a friend wanted to get rid of. It opens a world of opportunity for getting consoles, etc.

Plus, I'm enjoying how my 6 yr old daughter responds to the loss of color.. before she'd complain, now she turns the fine tuning a touch and makes it work, ever 10 minutes. Somehow that's just enough to get the color osc. going again.

[Electronic M]

I haven't gotten to my set yet so the reply was actually EARLY by a couple of weeks.

Your daughter sounds like a smart kid, just keep your fingers crossed that she never messes with the grayscale adjustments, etc on the back. When I was two I found a screwdriver and with in minutes I handed my folks the all the screws from the back door knob that I could reach, and so started my spree of dismanteling anything that I was not scared of.

[maxhifi]

Originally Posted by Electronic M

I haven't gotten to my set yet so the reply was actually EARLY by a couple of weeks.

Your daughter sounds like a smart kid, just keep your fingers crossed that she never messes with the grayscale adjustments, etc on the back. When I was two I found a screwdriver and with in minutes I handed my folks the all the screws from the back door knob that I could reach, and so started my spree of dismanteling anything that I was not scared of.

Well, experience is worth more than stuff, I think, even including my beloved Zenith. I can always put it back how it's supposed to be, but I can't force interest in anything. I'm glad she's looking at cause and effect instead of complainiing though, and with that attitude and a gentle touch I doubt anything will be wrecked by touching up fine tuning here and there.

When I was a kid I'd always wait for my parents to go out somewhere, so I could pick something to take apart and get back together before they returned. The only thing I took on which I never could get back together was the sewing machine... they had to get it professionally repaired, and I didn't hear the end of it for a while.

This TV has thrown me for a loop here and there, but I don't want to give up on it. Next step is probably replacing all the caps and checking all the resistors in the burst oscillator circuit. So far have done

-sub osc tube with NOS
-replace xtal
-re-solder connections on coils

Will throw in those parts next time I order from mouser or etc.

[ctc17]

Hmmm, maybe its not in the color demod circuit at all. Maybe its something in the front end or some kind of interference.

[maxhifi]

Originally Posted by ctc17

Hmmm, maybe its not in the color demod circuit at all. Maybe its something in the front end or some kind of interference.

Decided to do some digging. The problem had by now got bad enough it was happening all the time, and tapping the side of the TV would toggle the color on or off.

Took the back off the TV, and started tapping things, trying to figure out what is turning the color on and off, and I noticed something.

The color control is connected to the chassis with a shielded cable, which terminates in two crimp on connectors. These connectors slide onto the top part of Zenith's terminal strips. The signal connector was slid nearly all the way off, and barely making contact. This connector is very close to the recently replaced focus divider, and I bet I knocked it when I did that job.

I tightened the connectors with some pliers, sprayed some contact cleaner, pushed them back on their respective terminals, and then powered up TV. Seems that tapping the tv now has no impact on the color at all. Time will tell if I fixed it, but it looks good so far.

[ctc17]

Good Job. Sounds like that could have been it.

[maxhifi]

Originally Posted by ctc17

Good Job. Sounds like that could have been it.

Thanks! Let's hope so. Took me a while, and some wrong turns to discover it.

[maxhifi]

Quick update - still working perfect, can finally say problem solved. Time for something new.to work on.