My CTC-16XL Project.

[Electronic M]

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.

[Yamamaya42]

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.

[Yamamaya42]

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.

[old_tv_nut]

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)

[Yamamaya42]

Originally Posted by old_tv_nut

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.

[old_tv_nut]

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

[Yamamaya42]

Originally Posted by old_tv_nut

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 :/

[old_tv_nut]

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.

[Bill R]

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.

[Yamamaya42]

Originally Posted by Bill R

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

[old_tv_nut]

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.

[Yamamaya42]

Originally Posted by old_tv_nut

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.

[Yamamaya42]

decided to take a quick look a r145...
looks again , eyes pop out of head...
$%$%$^#$%#$!!! F%^%!!!
screams and swears in a very unladylike manner

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..

[Electronic M]

Originally Posted by Yamamaya42

decided to take a quick look a r145...
looks again , eyes pop out of head...
$%$%$^#$%#$!!! F%^%!!!
screams and swears in a very unladylike manner

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..

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.

[Titan1a]

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