RCA CTC-16XL Suggestions/Tips
 

Hello! I thought would ask the pro's of any suggestions and tips for my RCA 16XL. Is there is any must/recommended do's or things to look out for? It is in fairly good shape, looks to have very little work done to it and mostly original condition. The CRT tests really strong on a CR70 and has a great color picture. The flyback looks to be ok and does not have any leakage under it and that's nice to see.
However the vertical is a bit outta wack and no way to fill screen without stretching the top. Horizontal is close with the control at its max so I suspect I need to be checking out them sections for drifted components.

Also, is there a way to protect the flyback from melting down or failing? What kind of failure usually causes this so I can keep a look out for that. I thought a while back I read that there was a way to fuse it to help protect them, but for the life of me I cant seem to find where I read that at.

I'm excited to get this thing going :D Looking forward to watching Star Trek the original series weekdays on broadcast :D

I just want to say thank you to everyone for your input and help!

Oh, I did get a copy of the Sams manual as well

Hello fellow 16XL owner!! :)
Glad to hear yours is working so well... ( mine is not, No color via tuner, was the orig prob when I got it, then it sat for many years... )

First and foremost, in order to keep the FB safe cool and happy ( as I have seen it stated many times )
run through the horizontal sweep circuit adjustments ( page 7 under Misc, adjustments )
MOST important is the cathode current on v12 horizontal output.

Now many have stated that the electrolytics in these sets degrade quite a bit over time and are not quite up to the task any more, I have replaced most of mine, and it has made quite an improvement, but I'm still having a big headache with resistors that are too far out of spec. :(

Hey fellow 16XL owner! I have been reading about yours, quite a journey so far! I am sure you will get it squared away :D I am thinking maybe I will go ahead and replace all them electrolytic caps. I will have to keep ya updated on my findings. I think this weekend I am going to take on that cataract problem our sets have. wish me luck! lol

Who doesn't love seeing pictures of these old sets up and working :D

Needs a cataract surgery. Picture looks nice otherwise.

Indeed, I just finished the surgery too. First time doing it and was worried id ruin the tube, but it turned out good! now on to the electronics since I didn't blow it up lol

For the vertical problem, check the electrolytic capacitor in the cathode circuit of the output stage. Also, check the decoupling capacitor on the B+ end of the output transformer.

Thanks Tim! I will check them out

hi rocket, please check R102 150 K . that is between vertical height and vertical linearity. this resistor causes many different symptoms height adjustments. and it is common to fail in old sets. that is a part that I personally change every time with the original specification or a small increase in wattage.

Ooops.
 

CTC-16 vs CTC-16XL confusion bites again. :o
The resistor you refer to ( r102) is only present in the CTC-16 and not the CTC-16X (L) version,
The vertical circuits are quite different between the two.

going by the Sams for the CTC-16x (0818-2)

electrolytic capacitor in the cathode circuit of the output stage. - C4 50uf

decoupling capacitor on the B+ end of the output transformer.
C3b 80uf (through r108 1000ohm gets a bit warm ) only draw from 400v tap
I kind of blame RCA for all the confusion :/ the 16 and 16x are SO different, they should have had a seprate #, they even have different tubes in places :o

The vertical on the CTC-16X seems a bit strange :o
Height Pot is normal enough, B+ 390 (1) via r104 through pot r14 to gnd.
It's linearity (r13) that's weird, high side from 970v boost, but then the other side goes all the way to s6 (picture tube bias ) and then to screen grid pots ( via r193 194 )
not really sure what they are doing with this :o

All very good info bluenorm & yamamaya42!

I was looking over the schematic from sams and there is something very close in the 16xl. its R104 at 150k and it looks to be connected right up to the vertical height. R102 is also very close to the vertical height but its value is 3.3 meg and so is R103 at 2.7 meg. I am going to check on these later today and report back my readings : D

R104 has already been replaced from the looks of it. it tested out at 151k
R102 tested at 3.1 meg
R103 tested at 2.8 meg

They are all seem pretty close to spec.

Also noticed C-4 electrolytic has been replaced. Sams shows it as a 50 @ 50v and was replaced with a 47 @ 50v. that is pretty close. not sure if that should get switched out or not. I thought I read something once about its ok to go slightly above but not below spec. but that may have been for the voltage rating now that I think about it more. lol

A 47uf electrolytic is just a standard value that replaces 50uf. The tolerance on electrolytics is usually very wide, so when 50 was specified, the actual value of an individual unit might be anywhere from -20% to +50% or so.

The vert. oscillator plate load resistor frequently goes 'waay out of spec from being hammered by high level spike. This applies across all makes and models, both BW and color. Worth bookmarking.

that kinda explains why your 16-xl works so well and mine does not T_T, yours has been worked on before. mine is all factory orig parts. :( not counting tubes.

Under the 'Suggestions/Tips' heading there's one problem endemic to the CTC-12, '15, '16, '17 and '25. That's the two ground stakes on the far right end of the chroma board. They exist in one of two states; they're either cracked or gonna crack, and should always be re-flowed as a matter of course.

As i mentioned in the thread for my CTC 16XL, the entire chroma board had been removed at one point ( which i replaced ) when i first got it, I have now found it to be IF related ( not fixed yet ) As I can get color when I inject video at first video amp but not through the tuner. ( which was the orig problem before It was put in storage - no color )
so, they have been resodered on mine

Bookmarked! :) I am going to check on that one tomorrow

I will also reflow all of them spots as well, thanks for the tips!

Yeah, I think this thing was well maintained and kept clean and dry for most of its life. I was impressed when I ran across it! So far digging through this chassis it looks like 4 caps and 1 resistor has been replaced. I thought I had little done until now hehe

Took a break from checking caps and resistors and started working on cleaning tube sockets with DeOxit and tube pins as well all the pot controls as they were acting kinda finicky when I noticed that little pin that usually grounds to a tube shield and realized that I'm missing the shield! Took a peak at the schematic to make sure no others were missing. So I gotta find me one of them. Its on the 6gh8a Chroma Reference Oscillator. Kinda curious if any y'all know what kinda problems that missing shield would cause? :scratch2:

Adding or removing the shield could slightly affect the tune of the chroma osc. Shielding is important, but missing shields shouldn't cause harm...Just more noise radiated and or recieved.

Its prob not SUPER critical, they prob have it there to stop any RF energy from Chroma reference Osc. & control tube (v24 -6GH8A ) from bleeding out all over the place.

Not to be picayunish :)but the colorburst tube is not the oscillator. The burst tube supplies the synchronizing signal for the osc.

Edited

And they are timed by a horz pulse to grab & amp the 8 burst
signals on the back porch.

73 Zeno:smoke:
LFOD !

It's a miracle they ever got color working at all (and still have it compatible with B/W ) And when it did work, It was... Never The Same Color! ( my electronics taught us that one )
along with...
Bad Boys Rape Our Young Girls But Violet Goes Willingly … :o
There was also .. eli the ice man. ( barely remember that )

..And then the osc. free-runs during the whole scan period (one scan line) before the next synchronizing "burst".

If you still don't get full height, you may have to look at ALL resistors in there...
r98,99 ,100,101, (102,103,104, OK ) 106,107,108...
The only unknown factor is the VDR @ r105, Still not sure how they are ment to act, or test them. ,

I have been putting off checking all the resistors in my set for a while, as I wanted it to sit in an dry climate controlled environment for at least a month or more before I started, I brought it inside early Feb.

Glad the shield isn't super critical, still going to find one to replace it.
This evening going to go back to checking out more components and see what I find.
Don't know why but it's a lot of fun working on these old sets! It is totally amazing we were able to make color work back then and doing it all on fly without microchips and computers! Amazing so cool :)

“microchips and computers” Funny you mention that. :p
It's what I have spent the bulk of my life working on ( debug ) since I got out of electronics classes. :p

Thats awesome!! and here we are working on these vintage sets *lol*

Did some checking and it was out of spec, it was not really really bad but it was higher than it should be. Also found one on the horizontal section as well.

now that is odd, does yours have an RF shield over the IF board, like shown in the sams on page 17, Chassis top view? mine does not have it, or did not when i got it...

Indeed mine does, I went and took a picture for you to compare. I wonder if there are other things we could be missing. I also wonder how hard it could be to come by one of these shields... though could maybe make one out of thin sheet metal.

Which means, most likely that someone was messing with the IF before I got it, &I need someone to make a template from a same model 16xl when they have time, :)

If you pull the tubes and cut out for the protruding transformer can you could probably make a usable template out of paper from your own set.