I tried to do color AFC setup and could not...
went WAY out into the weird zone when i tried...
something is really strange with the burst amp
Sams says to ground this pin , and so on...
before i go grounding anything, I want t make sure I have the right pin and that things look OK, that is where things went wrong.
Sams says 40v
I measured over 160v:tears:
something aint right!
https://imgur.com/YNdvFez
i was clipped to the leg of r10 ( it checked ok )
v22 is new, r163 seems OK, but i did not check it out of circuit.
i have not had much time to poke around it yet, but i'm not sure why the cathode voltage is so high :yikes:
and i'm not about to short it to gnd until i see it in normal range... so I can't do the color AFC setup yet. :dunno:

? Did you make a typo? Where is R10?

R10 is the 1 meg color killer pot.

OK, this just got a whole lot weirder... I seems whoever worked on this before me, ( the jerk who removed the cover off the IF board and lost it & REMOVED the color PCB... ) noticed the problem with the burst amp, and tried to fix it... because when I checked r163 and r144, they have already been replaced with metal film 2%, so I'm still in the dark as to why the cathode v is so high....

Rocket. if you ever get a chance, with your chassis in service position, and a good stable color pic, can you measure all the voltages on R10 ( color killer pot ) Sams says they should be 30 ish in voltage

Yeah sure thing, I actually plan on throwing the chassis in for a test run tomorrow to check and see how its performing after replacing a few caps. : D

Got them measurements while running with good color picture.
measured color killer pot, 3 terminals. 1st term closest to power supply side of chassis is 53.1, mid term 1.184, 3rd term 33.70 :thmbsp:

If I have learned anything over the years, its never underestimate the stupidity of those who came before you.
Poking around the color pcb I have seen that most all resistors have been changed, with what looks like 1 watt carbon film, it calls for ½, and this is no problem really. I'm using ½ metal film, you can see the 2 new one I just put in in the pic, they ALSO replaced some caps, cause some disc one look new, and the person who did it, does not know how to shape leads correctly cause I see a lot of cracked meniscus, a big NO NO in my line of work, but THEN I SEE what is shown in the pic, problem with c96, and no doubt causing my voltage problem... WTF? Very careless...
https://imgur.com/YTsHAxc

Rocket, your readings are right where they should be, thanks! :D

Awesome! and no prob :D

Well, putting that cap in did not help, cathode voltage is still high, 135v where sams says 40v.
I'm not sure how this burst amp circuit works.
Do I ignore the fact that I see the high V on there a try to run the color AFC anyway ? Good chance it wont work.
I DO See the waveform on grid 1 as shown on sams, it looks like the lower one for color, and never changers, no matter what is on screen. 150V should be 50v horz rate Way too high I'm being flooded with horz freq?



any idea what may be doing this? I do see lines to the FBT, for what I assume is horz pulses.

I suspect either V22 has a short or it has a DC bias voltage issue.

i got it "new"

i guess i can try another

What is the voltage on pin 2 of v22? Have you changed the cathode bypass capacitor, and the screen capacitor c98 and c99? Have you checked the 255 volt source? Don't rule out a bad tube, even if it is new. Check the resistors 163 and 144 out of circuit. What about c94?

All resistors have been replaced before i got it wit carbon film, and just to be safe i replaced 163 and 144 again,

who ever had this before me did a lot of weird stuff to it.
I do not think c98 and c99 have been replaced, they still look old.
all bias voltage is OK, checked them when i replaced the electrolytics
I have ordered a new tube anyway.

another potential problem
I don't know if its related to the burst amp and color killer circuit problem or the is even more problems,,,

looked at c22 ( hooked to output of 1st video amp ) feeds chroma bandpass , and good signal on the 1st video amp side, nada on the other. could be that CK is just not working right with the burst amp borked and clamping down, or its a sign of another problem :/

Here is where things are now...
The set it pretty much in the shape as when I first got it. ( after undoing the color PCB being out ).
No color, sometimes barber-pole effect seen, unknown if it's IF related, (evidence of work done in IF PCB )
ALL resistors replaced on color PCB , except for higher power ones, some disc caps new, not sure of any else.
Apparent burst amp / color kill problem , which I am assuming is shutting off chroma bandpass, ( if I understand the circuit ) .
No video signal seen out of c22, feeding l24 ( bandpass coil ) . Saw suggestion in other thread to short point E, to force on, not tried yet.

Cathode voltage of burst amp too high, (V22) not sure why yet, all resistors new, tube “new” (another ordered) voltage starts at 20v when first turned on, and jumps to about 130v when horz kicks in.
plate/g2 voltage OK, was unable to measure g1 voltage with DVM, due to strong waveform on it ( gonna have to get my analog meter cleaned and working ) .

New, ( relatively ) v22 6JC6 coming fri, & a set of HV disc caps come mid-week, will replace c95,98,99,100 and re-test this weekend.
I hope this does something... but it may not, there may be problems elsewhere, as mentioned, I still don't fully understand this circuit yet, it seems to be a balanced feedback setup, but that is a guess.

The barber polling is probably weak color getting through. The chroma osc if not adjusted perfect will loose sync on weaker color signals, but sync to strong ones.

I believe I have found an error in the Sams for the CTC-16, (surprise surprise ) this is present on both the 16 and 16x versions. (sams 818-2 & 736-4 ) .

If you were to look at the waveforms on the input to G1 on the burst amp on both, one is marked for color input ( square symbol ) but It shows no video information between the pulses, the one above does.
I have checked the sams for the CTC-15 & CTC-20, and they are opposite of what is shown here.
Video information is seen on the lower waveform ( marked for color ) and none on the one above, somehow they are backwards on both CTC-16 schematics.
To me it has always made more sense for it to be the other way around, thus I was looking at other schematics.

this is what has me confused...
Am i reading too much into it? an just go with is on the sams?
https://imgur.com/g4gMKmr ctc-16x
https://imgur.com/KsYqFI8 ctc-20
https://imgur.com/fDhZQ3W ctc-16


EDIT...
I'm still disturbed as to why that wave on G1 was so high, this may be the cause of everything, overpowering any video trying to get in, source is FBT pin 7, also goes to conv socket , pin 8, where it's shown to be at 270v , when I get the cap set in, add to check list, c94, c97, r145, r146, ( did they put a wrong part in? )
There has to be some reason that the horz pluses going in are so high that the Amps can't work.

Yamamaya42, what kind of meter are you using to measure the DC on the cathode? Could it be the pulse waveform is fooling it?

Another way to measure DC on a pulse waveform, with a scope:
1) set the scope for AC and center the waveform vertically within the screen.
2) note the level of any convenient point of the waveform
3) change the scope setting to DC
4) note the CHANGE in voltage of your picked waveform point (the DIFFERENCE between the reading in AC mode and DC mode) - this is the actual DC (average of the waveform)

I thought of that, and I looked for a waveform on the cathode and there was none, even with the o-scope turned down to 500mv, but for some reason I'm seeing a wave of over 150 in G1, which I don't think is right at all.

I plan on re-testing with a analog volt meter later, but something tells me that horz wave is too high , for some reason SHOULD BE 50v max, and they made a mistake someplace when they were putting new stuff in before i had it.

oops - I got confused where you are seeing a waveform and where DC.

I just checked it,, there IS a 10v sawtooth on the cathode, its prob related to the massive wave being fed into g1, hopefully I can work out what is causing this all :/

The pulse on G1 seems to come from a 3:1 voltage divider consisting of R145 (100k) and R144 (47K). I would check that the values are correct and R144 is not open / disconnected from ground.

Do yourself a favor and resolder ALL of the points where that circuit board solders to the chassis. These are used for ground connections and will cause all kinds of strange problems. Use a higher wattage iron so you can get enough heat on the chassis stake.

As i mentioned earlier in the thread, some fool REMOVED this PCB, and I replaced it when i got it, so they have already been re soldered.
the handy weller 8200 i got from my dad did nicely for soldering the gnd points :p

Scope each end of R144 directly. You should see the 150 v pulse on one end if it's connected to G1. You should see zero on the other end if it's actually grounded.

If you see zero on both ends or 150 v pulse on both ends, one end or the other is not connected.

I will check that this weekend, tks, I replaced r144 & r163 last weekend, cause i suspected something, I will check more of the carbon film ones that were put in this weekend, esp r145, when i replace some of the disc caps that look like they have not been replaced yet.

decided to take a quick look a r145...
looks again , eyes pop out of head...
$%$%$^#$%#$!!! F%^%!!!
screams and swears in a very unladylike manner
:yikes::wtf::mad:
https://imgur.com/82LmbdD

that is NOT 100k!!
brown blk orange??
no wonder everything is messed up...
how many other resistors did they get wrong.. :cry:

Stupid mistakes: even smart people can make them.

I spun my wheels on something stupid on the Silvertone CTC-15 I restored as my first roundy and my first color set that genuinely needed a resto to work...The thing had a shrinking monochrome raster when I powered it on a variac so I recapped it and then it had no HV. I went over the horizontal for well over a month, gave up, then needed to borrow the damper for another set I needed to take pics of for a college project...Then I realized the damper which had been fine on the first power up and initial tube testing had shorted after I recapped it...Then suddenly with a good damper inplace I was chugging through the resto again.

Shows your humanity. Now you're trustworthy. You're now Sherlock Holmes!

i'm going to have to go over the whole PCB now and check all the res they put in now, knowing this, I should never have assumed they did it right when I saw that the Resistors had been changed T_T.

Hot damn! :banana:

did a quick change of r145 to the right value, and cathode voltage of Burst amp is right on target! 41v.

Will go over the PCB this weekend for other wrong resistors, and attempt color AFC setup again! :thmbsp:

Woohoo! Fortunately you found it. Unfortunately you will have to be suspicious of everything the previous guy touched.

Awesome!!
Cant wait to see this set running : D

Sucks the last guy screwed up so much on this set and will have to be suspicious of everything. However it will be pretty rewarding when you get this thing running :)

Latest status
Still unable to to preform Color AFC Setup.

Only able to see barber pole effect. ( still may be IF related, unknown )
BW pic is very stable.
Cathode v on burst amp is now at 40v, where it should be, but seeing a 10v saw tooth wave there, not sure if this is normal.

Not finished going over PCB for other errors yet.. :(
evidence that L24 ( bandpass coil ) may have been replaced.

STILL getting no scopeable video on the far ( badpass ) side of C22, it also looks to have been replaced. Removing v17, killer / chroma bandpass tube makes no change in this, but lifting the far side of the cap does.
This situation was first spotted years ago when I got the set.

Will have to try and dig deeper ( find other errors ) to work out why it's dong this,
From what I understand, and how this all works, if NOTHING is getting past C22, or its getting distorted somehow, there is nothing for the Burst amp and bandpass to work with, and thus the color osc can't lock on and so on...

I should see SOMETHING on both sides of C22, right?

If the chroma osc is too far off freq it won't sync even with ideal sync input/synch circuit performance.

Sync or not you first need to get it to the point where you can tune the osc to not have many barber Pole lines but what looks like continuous to tint drift... once you get that if there's any life in the chroma sync it should be able to lock.

but i'm not sure I'm getting anything for it to lock onto.
I'm seeing nothing at the bandpass coil even wit the tube removed ( same tube has the color killer )
there are no pules at all v23 chroma phase detect.

what should i be seeing at point 80 ( v17 removed )? I'm seeing nothing but noise, no video, the overpowering horz pulse that was there is gone, but, no video, so i suspect there is an error someplace that i have not found yet . :(

Sawtooth on cathode is normal.

Back of envelope without using exponentials: Average current is 1 ma (40v/39kohms). This is supplied in a narrow pulse of, say 2.5 microseconds, or 1/20 of the horizontal rate. So, the peak current is 20 ma for 2.5 microseconds, = 50 nanocoulombs. This causes a rise of 5 volts on 10 nF C98.

Copied from “no color on CTC-16” thread, almost exactly like mine.

Posted by Old TV Nut.
So, go back to grounding point E. This should defeat the color killer and let the bandpass amp conduct. Turn the color control all the way up and see if you see any color.

As far as using the scope, set the scope sweep rate to horizontal sweep rate (about 10 microseconds per division). For starters, set the vertical sensitivity to 10 volts per division (or 1 volt if you have a 10X probe) and check for presence of all the waveforms shown in the SAMS schematic for the chroma sync phase detector and color killer, plus the chroma bandpass. Set the vertical to higher gain to view the smaller waveforms that are marked about 10 or 12 volts peak to peak.

Do you have a color bar test pattern to use, or are you using some program video? The chroma waveform on pin 3 of coil A14 will generally not be as big and obvious with program material as with a test pattern, but you should be able to see it come and go when the color killer operates.


This is most likely the source of my problems now, As when Point E is grounded, I get absolutely nothing at g1 of u17 ,even at 200mv, I just see noise , nor is there any signals at chroma phase detector,
but the ref Osc is running, I can see that, not sure what freq.

I do see the horz pulse at g1 of the burst amp, but it still never changes with the video on screen, even though that r145 is correct.
What I don't know (or understand yet ) is something so messed up in this circuit that won't allow video into it through c22 (from 1st video amp) for any of the color to work correctly ? Could IF section be so out of wack that it is not letting any color through for the circuit to work with? A combo of both perhaps?

OK, update...
After spending nearly 2 hours checking every resistor that was replaced on the color PCB, I found one more that was wrong, R170 has a 10k in it where it should be 27k ( so says SAMS ).
Other than a lot of crappy lead shaping and sloppy solder work, the other resistors are OK. ( I have a very critical eye for lead shaping and solder form, this comes from my many years in the industrial electronics field ) .
There are a few caps that still look old, that I will most likely change this weekend.
However, I really doubt that this will fix the problems, for I'm pretty sure that the putz who did this messed with the IF section and I have no real way to align it.

So once I am done checking the color PCB, I will try again to tap in video at the 1st video amp, this time lift up one end of l9, and try color setup with external video, this MAY cause a problem because composite video is 1v PtP and the wave shown at that point is 3.5, I may have to build a small video amp, or it may not care.