My CTC-16XL Project.

[dtvmcdonald]

Peaking value coils are never critical. In fact, its sort of silly worrying
much about just the value, unless you can get a for certain absolutely exactly original
factory model coil.

You see, these thing have capacitance across them and thus are parallel tuned circuits. Whether they are used in series with the signal or as a plate load, that resonant frequency matters.

And the "standard replacements" listed are often, while close in low frequency
inductance, way pff in parallel resonance. That can make for a bad picture.

I have an RCA CT-100 color TV with lots of peaking coils that are potted in something white that corrodes them. In fact though some of mine were bad, none were
so bad I was unable to unwind a few turns and get measurements of inductance and resonance. I had to experiment to get the waveforms to look right. I bought
two or three coils for each replacement. The best inductance value varied
up to 35% from spec. Most were noncritical but a couple were critical.

Putting coils in series thus generally simply won't better than just getting close.

[Yamamaya42]

on the "to do " list next time the chassis is out.

Replace R70 (out of tol) , & C31,R71 just to be sure, they are most likely OK , but new parts won't hurt, hopefully this can cure the retrace problem.

Inspect delay line VERY closely, checking for any damage at the grounding point, and see if repair/ replace needed, re-connect ground to OEM position, similar to as seen in GE chassis. Replace L13 that had been slightly damaged with NOS RCA part. Replace R64 with new 2% part, it's most likely OK, but while I have it out, why not, inspect L15/L15, they are on the topside of the PCB, and unlikely to be bad.

Check remaining original orange drop caps for leakiness.
Replace focus resistor & cap.
Fix the damn loose connection on the heater pin on the socket of the HOT.

I did manage to view the entire DVD , Watchmen Director's Cut, this weekend with it, and I saw no macrovision problems whatsoever, I'm not sure if it was because of the player used, or the DVD, or because I was using direct A/V input, but it was very stable, no problems at all.

[Yamamaya42]

Damn, L13 will be arriving surprisingly fast, It was shipped from within Texas, only 10 hours from here, It will be here Thursday.

The focus resistor, however, is coming from REEDLEY, CA, that will take a wile

does the 130 PF cap in the focus circuit really wear out that much and need replacing?

[Yamamaya42]

new L13 has arrived, no other parts yet, it does not look like the old one, but that is not unexpected,

https://i.imgur.com/pVTY6tn.jpg

found an old pic of the underside with the delay line and coil
https://i.imgur.com/1XZjvKL.jpg
you can see how I grounded it, and L13. (but not the damage to it )

waiting for the other parts

[Yamamaya42]

Well, USPS, “says” that the 66meg focus resistor is in the mailbox, but I won't fall for that again after the thermistor fiasco, I won't believe it until it's in my hands.

FEDEX says that the replacement for the 130pf cap in the focus circuit will come Friday, now there seems to be some flexibility on the value of a usable replacement, CTC 10-16 SAMs list no sub for it other than the RCA part# @130pf, but in the CTC 20, a 120pf is listed as a replacement, however, in the GE CTC 15 & 1/5 clone, it lists a 150pf as one, which I have used successfully, and since the focus circuits are all identical for the most part in all of them, I got another 150pf / 15kv for CTC-16XL.


Meaning that now, I should have have all the parts needed to do all the minor updated to my RCA that I had been wanting to do, including removing that black wire I have grounding the delay line, and grounding to the nearest gnd point via a heavy lead from a power resistor, the thicker, the better.

But, I'm still debating on to try it this weekend or to try and get the GE clone downstairs, setup and converged.
It's still too heavy for me to move on my own, so I'd have to bribe someone to help, or take it apart, IE remove the CRT from the cabinet and take them down separately, ( which I really don't want to do ).

The specs say a 21FJP22 is 43lbs, the cabinet rough guess is 20lbs? Separately, easy enough for one person to move, even with a shoulder that's healing fro surgery, together,, NOT... the chassis is very light compared to the CTC-16XL, and even the FADA rca 630ts clone, I was surprised at how light it was, like someone pointed out, GE= Good Enough.

Still not sure which way I'll go this weekend.

[Yamamaya42]

with them side by side now, i can really see the difference between the 21fjp22 and the 21fjp22A.

In the greens mostly. but I;m not sure if that is just a difference in the color/ video circuits of the CTC-15/GE and the 16XL.

[Yamamaya42]

About the focus circuit, I have seen it said that the 66meg (6kv) resistor gets hammered a lot and often drifts out of spec, I saw this in the GE-CTC-15 clone, but what about the 130pf ceramic cap? Are they pretty stable, or need attention also sometimes?

[Electronic M]

I've read a case or 2 of that ceramic cap going open-ish (not producing a good null on the eye tube of a restored 60's cap tester). But on average they are pretty reliable.

[Yamamaya42]

Then I don't think its bad in my 16xl, but I'm sure the resistor is worn, not that I CAN'T bring it into focus, but in order to do so, I'm almost at the limit of travel on the focus coil, so it can use a new one I'm sure.

Just another thing to add to the list next time I take it apart.

[Yamamaya42]

So far, my CTC-16XL has been going very well with hourly weekend usage, no major problems seen yet, other then the minor annoyances mentioned before.

So, until something pops up to urge me to pull it apart, I wont sweat the small stuff, but I may touch up convergence, it's a bit off again.
As stated before, on the list of minor stuff.

Replace the 66m focus resistor that seems to have drifted a bit.

Restore the grounding of the delay line to factory spec & put in new peaking coil to replace damaged one, ( though it may be OK, never hurts )

Replace resistors and cap on plate of video output, that gives vertical blanking. ( missed them when I restored it. )

That's about it.

[DavGoodlin]

Good to hear this is coming along, considering my break from early color 21-fun (till I'm driven indoors by cold) I have nothing new to report.

A video posted by Shang066 https://www.youtube.com/watch?v=caS-GKl19KA highlights the desirability of an RCA CTC16XL and how its easier to diagnose than a Zenith 24NC31, which will requires advanced troubleshooting!~

For my CTC20, a few issues remain including focus taking a few minutes to dial in, sound issue due to PC board connection, it did take a replacement of all the electrolytics to fix the pesky sync issue.

[Electronic M]

Originally Posted by DavGoodlin

Good to hear this is coming along, considering my break from early color 21-fun (till I'm driven indoors by cold) I have nothing new to report.

A video posted by Shang066 https://www.youtube.com/watch?v=caS-GKl19KA highlights the desirability of an RCA CTC16XL and how its easier to diagnose than a Zenith 24NC31, which will requires advanced troubleshooting!~

For my CTC20, a few issues remain including focus taking a few minutes to dial in, sound issue due to PC board connection, it did take a replacement of all the electrolytics to fix the pesky sync issue.

I always had the opposite experience from Shango. When I get an unrestored Zenith it typically works for the most part as is and just needs a few caps changed and some tweaking to work good.

Most RCAs I've encountered have had bad grounds, burnt jumpers, bad sockets, bad boost rectifiers, burnt flyback tires and various other issues that have to be found by troubleshooting.

[consoleguy67]

Zenith tvs were some of the best.

[Yamamaya42]

had a rather lucky mistake at work this week, of the many hundreds of PCBS built, they put the wrong parts on some, rather than a high power NPN transistor, they put a dual diode in, THIS one , https://www.mouser.com/datasheet/2/3..._D-2315355.pdf.
sice it was powered on and thus removed, it Can't be used in the correct location, and thus MUST be scrapped, and so I nabbed one from the scrap pile, as it seemed to be perfect for a horizontal phase detector when i should ever need one.

It's NOT damaged, Just can't be used as a " new virgin " part.

[Yamamaya42]

did a convergence tweak today.

https://www.youtube.com/watch?v=I5jhol_pSRo

can never et the top R/G vert 100%, and the upper right corner has always been dicey, but the rest is VERY good!
https://i.imgur.com/Oza4xm3.jpg


I think i need new caps in my pattern generator...

vertical linearity is also a bit off