Originally Posted by SwizzyMan (Post 3188108)

Found an open inductor on the video out tube. L72 on sams 180 Microhenry 9.5ohm. Is this an appropriate replacement? http://www.mouser.com/ProductDetail/...o%2f1lu29zY%3d

Originally Posted by old_tv_nut (Post 3188114)

Did you check L71 and R68 also?

Edit: also R69, L70, and the contrast control - these are all things that load the input or output of the delay line and need to match the impedance properly to prevent echos.

Originally Posted by SwizzyMan (Post 3188106)

I have been working on solving a ghosting issue in the picture.

Originally Posted by old_coot88 (Post 3188164)

By ghosting, do you mean ringing (parasitic amplitude ripples tagging after fine detail in the pic)? If so, try subbing the last IF tube if you haven't already. It can cause ringing even if it tests good on a tester.

Originally Posted by old_tv_nut (Post 3188375)

Suggestions:

1) make sure the value isn't off by a decimal place or something
2) check for open resistor in parallel with either L72 and/or L71

If it's not those, check all other parallel L-R combos in the video amp chain.

Originally Posted by SwizzyMan (Post 3188378)

Value is fine. Checked all coils and resistors that may be in parallel with them and they all check fine except for a coil on the B-Y amp that reads 1.2 meg, but I dont think that one really matters for my current problem. I hope its not the delay line causing this!

Originally Posted by old_tv_nut (Post 3188379)

Are these components on a PC bOard? Maybe a bad solder joint? Try bridging a resistor directly across the coil?

Originally Posted by SwizzyMan (Post 3188382)

Now on to the color for now. Everything seems to be fine except for colors with magenta. As you can see the magenta bar fades off into red which I attribute to bad phasing in the G-Y(?) channel. I just am not sure how I would fix it (Phasing adjustment?).

Originally Posted by old_tv_nut (Post 3188384)

it really would help to put a scope on the R-Y, G-Y, and B-Y outputs to see which ones are smeary. It may be the B-Y amp. If all are smeary, it may be a chroma alignment or even IF alignment problem. How is it affected by fine tuning?

Originally Posted by SwizzyMan (Post 3188385)

Doesnt seem to be affected by fine tuning at all.

Originally Posted by old_tv_nut (Post 3188386)

Then you can cross IF alignment off the list.

Originally Posted by Penthode (Post 3188405)

Interesting the worst smear is between magenta and green. This color transition is the greatest phase swing. This suggests that the chroma channel response is bad.

The chroma response of the later (CTC4 on) sets is dependent upon a good complementary video IF and chroma channel response.

Originally Posted by old_tv_nut (Post 3188413)

Second this, but seeing it at both demodulators would confirm it.

SwizzyMan, what kind of scope do you have? If it is capable of syncing on a separate signal from the one you are viewing, it's good to know how to do that for future reference. You could sync on the luma, the sync separator stage, or just by putting a probe somewhat near the flyback (not too close!), and then look at whatever you wanted with the other input.

Originally Posted by SwizzyMan (Post 3188418)

Its a tektronix TAS 220. 20 mhz analog scope, not the greatest but it normally works.

Originally Posted by miniman82 (Post 3188572)

Uh, that's how you're supposed to do it...

Read the alignment instructions, or better yet if you have a B&K 415 use that it'll cut your time in half.

Originally Posted by Phil Nelson (Post 3188627)

Do you have a restored B/W set that works well, that you could use to practice alignment (again, doing the setup and looking at the traces, without changing adjustments)? The setup wouldn't be identical, but maybe that would help you get the hang of things.

I had reached a similar point with my CTC-4 and I took a stab at building a video preamp, which turned out to be not as simple as I hoped. This old thread has more details:

http://www.videokarma.org/showthread...259995&page=23

The last color bars that you posted look pretty good, apart from that one anomaly. What does the TV look like when you view regular content, such as a DVD or cable TV? Sometimes things that look less-than-perfect in test patterns don't interfere much with everyday viewing.

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

Originally Posted by Phil Nelson (Post 3188678)

Regarding a video preamp, I just updated my CTC-4 article with a new section at the end, describing what I built:

https://antiqueradio.org/RCACTC-4ColorTelevision.htm

My preamp didn't work, due in part to a wiring mistake. I fixed that and messed around a little more, and then pushed the whole thing aside because I was burned out on the project.

Anyhow, I have to believe that the basic design, taken from the 1956 article in RCA Broadcast News, will work if someone takes the time to build it correctly.

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

Originally Posted by andy (Post 3188722)

Not trying to hijack the thread, but I'm also working on a CTC4 with some similar problems. Possibly we can help each other.

So far, it's been recapped and I've replaced all the out of tolerance resistors I can find. It produces a reasonably good B&W picture, but the chroma is VERY noisy. It looks like the kind of noise you see if the fine tuning is way off, or with heavy RF interference, but the picture looks good with the color turned down. Sound is also good.

I'm not sure what's normal for a CTC4, but I find that I have to set the color control a lot higher than on most other sets. I suspect it could be a problem with the chroma band pass (misalignment or low gain).

I have not checked the alignment yet other than the basic chroma demodulator adjustments. I can do a full alignment if I have to, but this one looks like a very complicated job.