my roundies are frequently needing more repairs

[Adam]

It seems that I'm always fussing with these old color sets. They look great while they work, but new problems frequently appear. Are any of you other guys here using roundies on a regular basis finding this. Were they like this when new?

My Philco combo now has this problem where if you turn the brightness or contrast below a certain point, the picture starts flickering. It sort of looks like those hum bars you get from leaky filter caps, except going much, much faster up and down the screen. If I leave the set on for about 30 minutes or so it only happens when I turn the brightness almost all the way down. It also has that problem with ghosting I discussed earlier in it's thread.

The CTC-10 is very susceptible to interference which appears on ch 2,3,4. I can sometimes notice it on other sets, but it comes up way more on the ctc-10 (my computer monitor is a large source of this, and so is any dvd player I use - but there must be something else because I can never completely be rid of it). I replaced the missing shielding over the video IF board, but that didn't fix it. The tint control has also become largely ineffective, which actually isn't that bad, because the tint is stuck about where it should be.

And the Zenith has this problem I talked about in it's thread with jumping in and out of focus.

I'd like to be able to fire up all 3 roundies and get a perfect picture while I still have good old NTSC analog tv coming from my antenna, but the sets seem to have other ideas.

[jpdylon]

what a bummer. I've not had the troubles you've had. I have a CTC-11 that I used daily (for about 2-3 hours a day) for the past year. About the only problem I had was a faulty rectifier diode in the LV supply. Other than that its been a good performer.

I have another 11 that hasn't been restored yet, and a 12 that's all original and working. Guess I got lucky or have low hours sets?

[compucat]

I have just one color roundie, my 1965 Zenith 25MC33 that I have been using regularly for almost two years now. It is a top notch performer. That said, it is in its third vertical output transformer. Just last night I had it on and the vertical acted like it was going to collapse for a couple seconds then no more trouble. I have been using it a bit less lately because I'm begining to question the reliability of a device that uses 25 tubes and hundreds of other components. I think the failure rate may be increasing for color roundies simply because of their age and sheer number of parts. The circuits are not particularly complex, there's just so many of them. I sure wish I had a spare chassis from which to scavenge parts.

As of now, the Zenith is still running and looking great.

[andy]

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[Robert Grant]

I noticed when I started repairing discarded TV sets as a hobby (about 1979) that color sets were far more prone to problems than B&W sets.
My parents' RCA CTC-38 was frequently breaking down from about its sixth year onward (with a couple of failures, including the power transformer, well before that). Toward its end (11 years), it seemed every part had a lousy connection to the PC board and/or tube sockets.
When I started buying schematics, the reason became clear - four times as much stuff to go wrong.

[zenithfan1]

They're getting old, my friend. I use a '65 Zenith with a 25MC33 chassis regularly. After the restoration, it had a few problems as usual but they ironed out. So far, the roundies I fixed have stayed fixed. However, they don't get used much besides the one I just mentioned. Your problems seem to be cap and resistor related and you should be able to track it down. Good luck, I hope you get them going right.

[kx250rider]

Originally Posted by zenithfan1

They're getting old, my friend.

That's it. But since it's our hobby, it wouldn't be any fun if they never needed any work. I don't watch any vintage TVs on a daily basis, but I did use my '72 Zenith 25DC56 color set on a daily basis up til about 2 years ago, then my ex-girlfriend continued to use it until 6 months ago, when a friend gave her a wide-CRT RCA hi-def set. I picked up the Zenith, and it's here at my place, but I never seem to use it anymore. I've had it since I bought it at the Salvation Army store in '81, so I'll keep it. It's been with me through earthquakes, many moves, and a fire.

Charles

[bgadow]

I don't watch enough TV to really wear one out. (I honestly can't remember the last time I turned a set on for my own use) We know they were notorious for poor reliablity when new, and that 40-50 years won't help matters. But we might also think our skills as restorers could work out all the bugs. Ah, but there are A LOT of bugs in a tube color set!

[OvenMaster]

40 years ago, I lost track of how many times I'd walk with my dad to the drugstore to use their tube tester. TVs really weren't all that reliable back then.

[old_tv_nut]

Connections get bad, pots get dirty and intermittent. Insulation deteriorates. We all know about the old caps. One thing I didn't expect, but found on the CTC-5, is that many of the carbon comp resistors are higher in value than rated - but I'm not going through and replacing every part unless it really causes a malfunction. At one point, the power-dropping resistor for the tuner went up in smoke - for no known reason, as the tuner draws the correct power now that the resistor is replaced.

I know - Gremlins!

Regarding the flickering at low contrast/brightness, one guess could be the high voltage regulator circuit - you might try changing the regulator and/or checking resistance values in the horiz sweep and high voltage section.

[jeyurkon]

Originally Posted by old_tv_nut

Connections get bad, pots get dirty and intermittent. Insulation deteriorates. We all know about the old caps. One thing I didn't expect, but found on the CTC-5, is that many of the carbon comp resistors are higher in value than rated - but I'm not going through and replacing every part unless it really causes a malfunction...

Nearly every 100K resistor in my Sylvania measures 140K. Even the ones that dissipate almost no power. I checked the multi-meter and it's fine.

I never expected resistors to age under those conditions.

John

[truetone36]

All my color sets have issues but one, a CTC-15 I found in an alley on bulk trash pick-up week, which is still chugging along on it's original caps. It has the beginnings of a cataract, and so is not a daily watcher. The one that gives me fits is my CTC-24 which I have nothing but trouble with.

[MRX37]

Replace every original cap, pot, and resistor with new parts. Tedious, time consuming, and probably a major hassle, but it'd probably fix a lot of gremlins.

I know if I had a TV that I wanted to eliminate every gremlin on, this is what I'd do. It'd probably take a month of Sundays to do, but there'd most likely be no more trouble from the set. well, up until it blew a tube...

[Adam]

Now that the Zenith is running again, I'm just going to start using that one as a daily watcher, and only turning on the others once every few weeks or so. Using a large percentage of my collection as watchers leaves me always doing repairs on sets I already fixed, and not getting to work on new stuff.

I think people must have just watched sets with minor problems all the time, I'm always hearing how all early color sets had bad pictures (even though we all know this is totally untrue), I think people just used to watch them when they weren't quite working right.

[zenith2134]

Aside from the energy inefficiency and HEAT inherent with the old tube color sets, it can be a nightmare keeping them all looking their best. Especially as daily watchers...

This is another reason why I like the early-80s and late 70s tv's too. They tend to go forever, and give a great pic once they're all tuned up. Plus, if they are beyond repair, it's usually not a big deal to have to toss one.