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-   -   CTC-4 Director 21 (http://www.videokarma.org/showthread.php?t=267400)

SwizzyMan 08-19-2017 08:57 PM

Quote:

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?

All point to point wired. Resistor did nothing. I think I will just get the color set up and worry about this later, maybe I'll think of something while Im doing that.

SwizzyMan 08-19-2017 09:11 PM

1 Attachment(s)
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?).

old_tv_nut 08-19-2017 09:45 PM

Quote:

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?).

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?

SwizzyMan 08-19-2017 09:48 PM

Quote:

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?

Doesnt seem to be affected by fine tuning at all.

old_tv_nut 08-19-2017 09:55 PM

Quote:

Originally Posted by SwizzyMan (Post 3188385)
Doesnt seem to be affected by fine tuning at all.

Then you can cross IF alignment off the list.

SwizzyMan 08-19-2017 09:58 PM

Quote:

Originally Posted by old_tv_nut (Post 3188386)
Then you can cross IF alignment off the list.

Thank god. I will have to hook up the scope tomorrow.

SwizzyMan 08-20-2017 09:29 AM

Using the scope proved inconclusive, I couldnt get the scope to lock on to any trace coming from the demod tubes. The trace wasnt stable enough to get any pictures of it without it being cut off. Hmm, should I just try a color set up per the manuals instructions?

Penthode 08-20-2017 01:25 PM

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.

old_tv_nut 08-20-2017 03:34 PM

Quote:

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.

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.

SwizzyMan 08-20-2017 04:40 PM

Quote:

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.

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

old_tv_nut 08-20-2017 05:12 PM

Quote:

Originally Posted by SwizzyMan (Post 3188418)
Its a tektronix TAS 220. 20 mhz analog scope, not the greatest but it normally works.

Nice little scope - you can trigger on channel 2 and poke around with channel 1.

SwizzyMan 08-21-2017 07:41 PM

Can't seem to get the scope to trigger. I really need to look for a better one here soon anyway. I'll keep messing with it, maybe I can get it to trigger.

Bill R 08-21-2017 07:58 PM

What I see is video ringing in the earlier picture. Looks like you were on the right track with the peaking coils and such in the last video and IF strip. The color problem is what we used to call poor color fit. More often than not it is caused by a problem or poor alignment of the IF strip. I would set up to do an IF sweep alignment and see what the response curves look like. A proper IF alignment may solve both problems. I will bet it is off more than you think.

SwizzyMan 08-22-2017 04:50 PM

Sounds like an alignment is in order this weekend. Unless I can do it with the chassis on the bench with no hv or crt.

miniman82 08-23-2017 07:45 PM

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.


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