My CTC-16XL Project.

[Yamamaya42]

Originally Posted by old_tv_nut

Wild stab: have you checked rectifier X6 and the parallel resistor R217?

they're both brand new, however, i did try putting in a resistor that was 30 ohms over the 270 ohms that was supposed to be in place in R217, after playing with it a bit, got this..
https://imgur.com/NFbWk5S

i will try to get a better pic later

[old_tv_nut]

Wow!

[Tony V]

It doesn't get much better than that on a roundie. Good job!

[Yamamaya42]

I still cant help but wonder what is causing the slightly annoying retrace lines to show up sometimes.

CRT age? No idea, the bias is at lowest setting, did grayscale setup a million times, no help. Will still show up when I turn up brightness high on some scenes, no matter the video source ( NOT macrovision )
Other than that picture is fine.

Still not quite sure how the horz blanking works yet. :/
VERY strong horz pulse from FBT on grid 230v @ -80v dc (on my TV ) , shows 115v on plate, goes to CRT bias switch and .22 uf to the Y amps. Shows it to be 15v on SAMS on bottom of tree, ( was 8-9 max on mine )



This is what I find a bit confusing and don't quite get, the Cathode of the blanking amp ( Cathode follower? ) is tied to the cathode of the bandpass amp.
Shown to be at 5v, no other info ( waveforms )

no cap or resistor on the blanking amp, but the bandpass has a 820pf 10% and a 390 ohm res, both replaced by the person before I had it.

I have seen no color problems since I got the color to work, and I DID check the resistor and the value of the cap looked OK, but I did not make sure they were exact.

Now since I really do not understand the circuit, I wonder, could this resistor / cap effect the blanking amp?
YES the 6gu7 is new, the 6gh8a is not.

[Yamamaya42]

I have looked at the horz blanking setup in the CTC 10/15/16/16XL/20 , and it very much looks like they use the same setup in all of them, with only slight variations.

Making a guess on how it works, using pulses from the FBT, (on the grid) it then passes the blanking pulses via a .22uf to the cathodes of the RGB-Y amps, tied to gnd with a power resistor at the end of the chain, wave can be anything from 10-15, depending on the set.

It also seems to pass blanking pluses to the cathode of the color bandpass amp (cathode follower setup), this is tied to gnd via 820pf / 390 ohm res, (all versions )
This I assume is to insert blanking to chroma, where the above is for luminance?
Only the CTC-10 shows what the wave is on the cathode, (10v ptp ), I will assume this is the same for all sets , or rather close, since they all have the same circuits.
https://imgur.com/yCoszDQ

At this point, I do not remember what the waveform was like at that point on my set, but as mentioned, I did not replace the 820pf / 390 ohm res off the cathode of my bandpass, as they were before I got it, but now I think I may try next time I have it apart & perhaps r188 (power resistor at end of -y amp chain) .

This also may get me nowhere, but I have replaced pretty much everything else in the blanking circuit.

Granted, I don't see the lines as much as a real problem right now, more of an annoyance.

[Yamamaya42]

:b anana:

HOLY CRAP I GOT ONE!!!!!!!!!

https://www.ebay.com/itm/RCA-113992-...-/223675445766

Just happened to be in the right place at the right time, and BOOM! , it was there!

Yes, it's for a CTC-16 and not a 16XL, but the diff can be adjusted for when needed!

[Electronic M]

Originally Posted by Yamamaya42

:b anana:

HOLY CRAP I GOT ONE!!!!!!!!!

https://www.ebay.com/itm/RCA-113992-...-/223675445766

Just happened to be in the right place at the right time, and BOOM! , it was there!

Yes, it's for a CTC-16 and not a 16XL, but the diff can be adjusted for when needed!

Congrats on your newly acquired hens tooth.

Your next mission should you choose to accept it is to acquire unobtainium.
This post will self-destruct in 10seconds.

[Jeffhs]

Originally Posted by Yamamaya42

:b anana:

HOLY CRAP I GOT ONE!!!!!!!!!

https://www.ebay.com/itm/RCA-113992-...-/223675445766

Just happened to be in the right place at the right time, and BOOM! , it was there!

Yes, it's for a CTC-16 and not a 16XL, but the diff can be adjusted for when needed!

I just saw the eBay listing for that flyback, and was amazed. $150? For just one color TV flyback transformer? That fly must be incredibly rare if the seller wants that much for it; that, or else the seller wants to get as much money as he can from the sale (the latter, unfortunately, is quite common on eBay; I have seen ridiculously high opening bids for 1950s-'60s TVs and radios, and cannot help wondering how the seller manages to sell the set, if he or she ever does). I could see paying that much for a flyback if the TV it goes with is very old and/or rare, but the RCA CTC-16 is from the mid-1960s, so replacements for any of its parts, including the flyback, shouldn't be anywhere nearly that expensive.

[Yamamaya42]

Originally Posted by Jeffhs

I just saw the eBay listing for that flyback, and was amazed. $150? For just one color TV flyback transformer? That fly must be incredibly rare if the seller wants that much for it; that, or else the seller wants to get as much money as he can from the sale (the latter, unfortunately, is quite common on eBay; I have seen ridiculously high opening bids for 1950s-'60s TVs and radios, and cannot help wondering how the seller manages to sell the set, if he or she ever does). I could see paying that much for a flyback if the TV it goes with is very old and/or rare, but the RCA CTC-16 is from the mid-1960s, so replacements for any of its parts, including the flyback, shouldn't be anywhere nearly that expensive.

Yes, I'm well aware that it is very overpriced, however, the 16 type FBT is one of the hardest to find anywhere, be it RCA, Thordarson , TRAD , or any of the other substitute make, used or new,
I had been looking for a year and a half for a spare, all over, and when I found this, I could not let it go!

[Yamamaya42]

and it has arrived!
https://imgur.com/uLnQnvP
https://imgur.com/M6SRgo5
and I did a brief test, and it IS new and good resistance wise, as what it should be on SAMS.
Chose a bit of Jay and Silent Bob Strike Back DVD to display for the test along with the ugly macrovision

When it comes to replacing the old with this one and it IS when and not IF, as it will happen sooner or later,
I already have a solid state focus rect, so why not go solid with the HV one when I replace the HOT?
with something like perhaps http://hvstuff.com/100ma-30kv-100ns-...high-frequency

thus remove all heater loads from the FBT.

[Electronic M]

That diode would probably work. You Could also get an IIRC R3A3 which is a plug in solid state replacement for the tube HV rect. They haven't been made in decades but some NOS are still hanging around.

[JohnCT]

Originally Posted by Yamamaya42

When it comes to replacing the old with this one and it IS when and not IF, as it will happen sooner or later,
I already have a solid state focus rect, so why not go solid with the HV one when I replace the HOT?
with something like perhaps http://hvstuff.com/100ma-30kv-100ns-...high-frequency

thus remove all heater loads from the FBT.

I replaced a couple of hundred CTC16 flys back in the day, and I recall the big rush was in summer months when heat and humidity got to them. Most of the ones that failed were from arcing from the 3A3 socket to the core - humidity related.

I honestly don't know how much you will gain by using a SS rectifier to reduce heater loads. I would guess it's probably a half watt of heat saved overall.

Unless you're going to run this 8 hours a day from now on, and do so in hot humid weather, I really wouldn't worry about saving the heater load on the fly.

Tom pointed out a SS stick rectifier drop in replacement for the 3A3. Dad used one on our CTC9 and lasted for about 10 years before the tube went and we scrapped it. I believe International Rectifier made it.

John

[Electronic M]

The CTC-16 and later style flys with the HV rect top cap integrated into the HV winding would also develop conductivity in the rubber covering the winding (shango66 has some videos on the subject). I don't recall if this was done but I recommend and tend to remove that rubber cover and replace it with sensor safe automotive RTV silicone.

[Yamamaya42]

Originally Posted by Electronic M

The CTC-16 and later style flys with the HV rect top cap integrated into the HV winding would also develop conductivity in the rubber covering the winding (shango66 has some videos on the subject). I don't recall if this was done but I recommend and tend to remove that rubber cover and replace it with sensor safe automotive RTV silicone.

The current FBT in there is still all original, no mods, I probably won't mess with it until something happens to it, then change to the NOS one and take time trying to fix it, if it can be.
The only other main point of failure now would be the CRT, but as mentioned, this TV is a bit unique with regard to others of it's kind, as it has spent more of it's life in storage (20-25 years) than being used, so there is less usage on the CRT.

[JohnCT]

Originally Posted by Yamamaya42

The current FBT in there is still all original, no mods, I probably won't mess with it until something happens to it, then change to the NOS one and take time trying to fix it, if it can be.

Tom and I were actually talking about the same thing. Most of the flys arced from the 3A3 cap socket to the core through the outer covering. A few would show a blackened area through the donut denoting a shorted turn.

Back when these TVs were everyday runners, a lot of people would let the TV run when it started arcing, maybe thinking it was antenna interference and wouldn't shut them off until the telltale smoke and stench appeared. By then it was often too late. I would see them with a totally smoked flyback and a burned 6JE6.

It's unlikely you or any collector will leave this TV running unattended or not immediately jump to your feet to shut it down if you hear arcing and see the distress in the screen. At that point, you can cut the outer red jacket off the fly where it arced through, clean it thoroughly, dry it, and put on the sensor safe type RTV (regular RTV will cause corrosion from the acetic acid).

If it were mine, I wouldn't use the new fly unless the original couldn't be salvaged.

John