My CTC-16XL Project.

[Electronic M]

Originally Posted by Yamamaya42

Yeah, that diode and cap are toast..
its a bit hard to find replacements using part numbers from a 50+ year old list, ( the resistor is easy )
i have picked mouser # 80-PHE450SB4220JR06 for the cap, and 625-RGP25M-E3 for the diode, i should prob replace that big cap and the little .001s on the screen pots, but they are most likely OK

These Panasonic caps are cheaper and a bit better for TV application (I use them in my resto work). https://www.mouser.com/ProductDetail...PvQRZAQNzTU%3D

This diode has a faster recovery time and is better suited for rectifying horizontal rate AC, and also has higher reverse voltage rating (Which can save your bacon if the ~4KV DC focus ever arcs over to the adjacent screens that are driven from boost). https://www.mouser.com/ProductDetail...OsoE%252B4c%3D

This is what I would buy if I were looking to replace those parts in my set.

[Yamamaya42]

total, $13 :/ its costing me more in shipping than parts

gonna replace the .001s out of safety, also getting a 0.47uF in order to do the HOT cathode current test, ( did not have one )

[Yamamaya42]

While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?

[Electronic M]

Originally Posted by Yamamaya42

While I wait for the parts ( coming tomorrow ) , there is something I've been wondering, on the schematic, (sams ) it refers to “spark gap” in a few places, like C155, but it is a normal cap, and not a spark gap capacitor, with slits in the top like I have seen before, but, they do have the leads of this cap routed in heavy stock cardboard, in what could be a spark gap configuration, is this what they mean perhaps?

Yup!

If you ever do a late 60's-mid 70's Zenith they use two pieces of magnet wire bound together with cloth shrink wrap. Anything (or rather any two things) conductive CAN be a spark gap if you want it to be, and there were plenty of things engineers tried to make them out of.

[Yamamaya42]

Boost voltage restored, I now know more than I did before.

I can almost get a pic locked in through the tuner, ( sound is OK ) pic is Horrid, and rolling horz. And there is NO COLOR via the tuner,( this may be partly due to the fact that i have 75 ohm hooked to 300, but unlikely ) this reflects the original problem with the set.
BUT if I tap in video at 1st video amp, I am able to get better sync lock and even some color lock ( a lot of barber polling)

This tells me the Original problem was most likely a messed up IF section.
I have not yet checked all the resistors in the IF yet,,, I stopped after I got a signal. I guess I have to check every one now.,,
but I'm not sure what I'll do w/o a known good Sweep Marker Generator...

[Electronic M]

Get the resistors in tolerance first...If you're lucky the alignment is fine and the only drift was resistor related.

[Yamamaya42]

A bit of confusion on the horz sweep ( cathode current ) adjustment.
The sams shows all these steps to do it... https://imgur.com/iZJm7bP
however, here this guy, ( who puts up very useful videos ) , did not show those steps, or omitted them.
Where they not needed and just skipped? Or done but not shown? I'm not sure what I'm seeing here, and if I should use that as guide for mine. ( also being RCA, same output tube )
https://www.youtube.com/watch?v=uBkSfc0aq8U

[old_tv_nut]

The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).

[Yamamaya42]

Originally Posted by old_tv_nut

The video is showing the efficiency adjustment as an isolated procedure and assumes the other adjustments in the SAMS are nominal.

SAMS adjustments:
The first two, for "floating" H sync, are to set the H oscillator to free run at nominal frequency so the horizontal AFC and horizontal hold controls are centered and don't have to pull it one way or the other to an extreme degree. I'm not sure, but maybe being way off center could affect the horizontal drive waveform, which in turn would affect the output efficiency.

[video procedure goes here]

The measurement across R136 is actually across R146 in the SAMS schematic on ETF. This is the HV regulator cathode resistor. Caution, it is floating at about 400v. This adjustment is to check if the HV regulator range is more or less centered. If not, you are instructed to detune the efficiency coil to get more HV supply, but simultaneously not go beyond the horizontal output cathode current limit. Ideally you should be using two meters at once (if not, you need to go back and recheck the HO cathode current).

Finally, you are similarly instructed to detune the efficiency coil slightly if you see horizontal fold-over in the picture (and should recheck the HO cathode current just to be safe).

Actually, “r136” is correct for the CTC-16X series, close but not the same as CTC-16 ( sams 0818-2 vs 0736-4)
Close, but different enough to be confusing, :/
example 3rd IF on CTC-16 = 6EJ7 CTC-16X = 6JC6A, many other subtle diff.

[Yamamaya42]

The only reason that I brought it up is, that while I'm playing with it ( testing / turning it on) and such, I don't want to risk any stress on the flyback, since they are so hard to find a replacement for.
As it stands now, the FB looks to be in very good shape for it's age, with no wax drip ( well, just a tiny bit) below.

[Yamamaya42]

Interesting...
was just poking around parts lists, it seems that the CTC16 and 16x DO NOT have the same FBT :O

16= 113992 (906160-501) and 16x = 115843 (906160-502 ) or so says sams.

Not sure what the difference is


Edit--

I see it now.
VERY different,
16 has HV REC / FOCUS REC of 3a3 / 1v2 and 16x has 3ca3 / 2av2.
HV/Focus circuits are quite different.

[Yamamaya42]

Not that I have come across a bad one yet ( that I know of ) going over the SAMS, which I have been doing a lot of, in several key places there are VDRs, (voltage dependent resistors) and I can only find RCA part #s for them listed, and little if any reference to what values they may be ( cold/hot or voltage/amp range ) , so in anticipation that IF, any of these have to be changed at any point in the future, how does one find a correct modern value replacement?

[Rocket]

Originally Posted by Yamamaya42

Not that I have come across a bad one yet ( that I know of ) going over the SAMS, which I have been doing a lot of, in several key places there are VDRs, (voltage dependent resistors) and I can only find RCA part #s for them listed, and little if any reference to what values they may be ( cold/hot or voltage/amp range ) , so in anticipation that IF, any of these have to be changed at any point in the future, how does one find a correct modern value replacement?

I was wondering about this as well when I was checking out values earlier today. I thought about searching the rca part number and see if I could find anything.

[Yamamaya42]

Originally Posted by Rocket

I was wondering about this as well when I was checking out values earlier today. I thought about searching the rca part number and see if I could find anything.

As to WHY, they are there, ( just a guess) is that they keep things stable as the set warms up and voltages drift, so the owner does not have to keep getting up to adjust like the horz/vert hold.
But I don't think that what is in there, behaves like the more modern MOVs...

and thus may be hard to replace.

[Rocket]

Originally Posted by Yamamaya42

As to WHY, they are there, ( just a guess) is that they keep things stable as the set warms up and voltages drift, so the owner does not have to keep getting up to adjust like the horz/vert hold.
But I don't think that what is in there, behaves like the more modern MOVs...

and thus may be hard to replace.

Yeah that totally make since and they probably don't. I got the RCA copy of the schematic today. have not taken a close look at it yet, but I wonder if any info will be listed on it. though if there is I doubt its going to list what were looking for