RCA CTC-16XL Suggestions/Tips

[Rocket]

Originally Posted by Electronic M

A useful tip when you disconnect the cathode lug of the socket run a wire from it to the top side of the chassis and add a fuse holder above chassis. Ground one side of the fuse holder, and connect your cathode wire to the other. When you're using the TV as a TV install a 250mA fuse to protect the flyback...If you ever need to check the cathode current all you have to do is pull the fuse and clip your meter to the terminals of the empty fuse holder.

Adding that fuse/holder above chassis both gives your flyback added protection and and gives you a convienent cathode current test point.

Great tip Tom! Thanks : ) it's now on my list

[Yamamaya42]

Originally Posted by Rocket

Yeah, its a shame that they didn't bother to put the shield back. Also I will be glad to try to work up a template for you from mine ; )

that would help a lot, tks.

[Rocket]

Originally Posted by Yamamaya42

that would help a lot, tks.

sure thing! Least I could do for all the help

I got the template done, drop me a pm with an addy and ill mail it over to ya

[Yamamaya42]

Originally Posted by Electronic M

A useful tip when you disconnect the cathode lug of the socket run a wire from it to the top side of the chassis and add a fuse holder above chassis. Ground one side of the fuse holder, and connect your cathode wire to the other. When you're using the TV as a TV install a 250mA fuse to protect the flyback...If you ever need to check the cathode current all you have to do is pull the fuse and clip your meter to the terminals of the empty fuse holder.

Adding that fuse/holder above chassis both gives your flyback added protection and and gives you a convienent cathode current test point.

"install a 250mA fuse to protect the flyback. "

I'm guessing slo-blow for this? And the voltage ratings (AC/DC) are not super critical ?

[Electronic M]

Depends on the current it runs. If it scores in the 170s a slow blow might not catch moderate issues till serious. If it scores in the 210s it may have regular nuisance blows if fast acting (my 21CT55 CTC2b does this).

Voltage rating is almost completely unimportant for fuses... especially given they were nearly all rated for 250v back in the tube era. thanks

[Rocket]

Originally Posted by Electronic M

Depends on the current it runs. If it scores in the 170s a slow blow might not catch moderate issues till serious. If it scores in the 210s it may have regular nuisance blows if fast acting (my 21CT55 CTC2b does this).

Voltage rating is almost completely unimportant for fuses... especially given they were nearly all rated for 250v back in the tube era. thanks

Hey Tom, what are you thoughts that if it scores higher and is a bit of a nuisance. Would bumping up to a 300ma fast or a 250 slow run a risk of not catching things quick enough? or better off sticking to the 250 fast to be safe

[Electronic M]

I'd be inclined to stay at 250 and go with slow blow...My gut feeling is the waveform spikes probably aren't going to reliably trip a 300 fast until the average DC current reaches the trip point of a 250 slow...

Another thing to consider is that some sets will have an increase of the static current during warmup or power off or changes in line voltage (which occur if the fridge, climate control, or local power grid your set is on cause voltage fluctuations*).

*That can be dealt with with a Sola VRT/CVT/voltage regulating line isolation transformer.....My local grid sucks so I've been forced to resort to these.

Fuses are cheap so you could probably grab 2-5 of each and experiment on sensitivity if you really want to get it to blow at anything above normal optimized parameters. Ultimately as long as it isn't nuisance blowing and isn't wildly above that point you should be fine...I've seen major non-flyback circuit failure (such as H osc. failure) drive the average cathode current well above 300mA. Most tube color sets that see daily use will need SOMETHING fixed every year or so...Thus if you check cathode current during that service you can catch issues developing.

[Rocket]

Originally Posted by Electronic M

I'd be inclined to stay at 250 and go with slow blow...My gut feeling is the waveform spikes probably aren't going to reliably trip a 300 fast until the average DC current reaches the trip point of a 250 slow...

Another thing to consider is that some sets will have an increase of the static current during warmup or power off or changes in line voltage (which occur if the fridge, climate control, or local power grid your set is on cause voltage fluctuations*).

*That can be dealt with with a Sola VRT/CVT/voltage regulating line isolation transformer.....My local grid sucks so I've been forced to resort to these.

Fuses are cheap so you could probably grab 2-5 of each and experiment on sensitivity if you really want to get it to blow at anything above normal optimized parameters. Ultimately as long as it isn't nuisance blowing and isn't wildly above that point you should be fine...I've seen major non-flyback circuit failure (such as H osc. failure) drive the average cathode current well above 300mA. Most tube color sets that see daily use will need SOMETHING fixed every year or so...Thus if you check cathode current during that service you can catch issues developing.

Sounds good I already have a 5 pack of the 250ma fast on the way, if I have nuisances and the readings look good perhaps I will try the 250 slow. How often do you have nuisance blows? and did it get any better with the line voltage regulation?

What are you thoughts of them ups battery backups? I currently use a few of them I kept my stuff on. Surprisingly the power doesn't seem that bad around here and it rarely has to kick in. I have noticed that I run a little on the high side around 121vac here. I will have to get out the meter and kick on the fridge and AC to see if I notice any drop in voltage.

[Electronic M]

In the CTC2 running at ~210-215mA with 250mA fast blows the fuses didn't last more than 3 hours.

Most UPSs I've seen don't regulate the line voltage at all...All they seem to do is switch to battery if the bottom drops out.

It will be hard to catch the most TV-noticeable line voltage change with a meter...When a large induction motor (fridge compressor, climate control, etc) kicks on for an instant it draws more than 5X it's power rating to get started...That drop is too fast for most meters (though if the steady state load is high enough that will register)...When a motor first kicks on you may notice a single flicker of the lights (at least if your still running incandescents like me)...On a tube era TV the raster will bloom with no correlation to video content...It can be very noticeable...There is an industrial park within 2mi of me and sometimes whatever they are doing causes blooming randomly every 3-6 seconds. I know it is the grid when I run 2 tube sets at once and both do it at the same time.

[Rocket]

Originally Posted by Electronic M

In the CTC2 running at ~210-215mA with 250mA fast blows the fuses didn't last more than 3 hours.

Most UPSs I've seen don't regulate the line voltage at all...All they seem to do is switch to battery if the bottom drops out.

It will be hard to catch the most TV-noticeable line voltage change with a meter...When a large induction motor (fridge compressor, climate control, etc) kicks on for an instant it draws more than 5X it's power rating to get started...That drop is too fast for most meters (though if the steady state load is high enough that will register)...When a motor first kicks on you may notice a single flicker of the lights (at least if your still running incandescents like me)...On a tube era TV the raster will bloom with no correlation to video content...It can be very noticeable...There is an industrial park within 2mi of me and sometimes whatever they are doing causes blooming randomly every 3-6 seconds. I know it is the grid when I run 2 tube sets at once and both do it at the same time.

Wow! indeed that doesn't last long at the high side huh, is it any better around 190 ma?

Yeah I can also see it in the lights, though its not very often. I wonder if an analog meter would do any better than a digital at seeing the fluctuations.

Wow every 3-6 seconds that's crazy! it probably is something in that industrial park

[Electronic M]

There probably would be a noticable improvement in life. To be honest untill the CTC-2 (I ranout shortly before that) I had been using mostly fuses from electronics I had been scrapping and hadn't checked if what I had was slow blow or not.

BTW: line voltage affects these a good bit. There are usually 2 line voltage taps on the transformer primary on most RCAs having it on the best tap for your line voltage or even runing the set off a variac set for balance between normal picture and minimum H output cathode current is not a bad thing to do.

Couple of other things you can do are to make a ventilation hole in the HV cage and mount a small fan to draw warm air out to cool the flyback. Also on the CTC-16 I serviced for a dead beat (guy still owes me money) that used to be active here. He wanted me to remove the rubber tire on the HV winding and replace it with Silicone based on this video: https://www.youtube.com/watch?v=BUnPkymnxUw which I sucessfully did for him. Apparently the rubber beraks down and becomes conductive sometimes as it ages.

[Yamamaya42]

Originally Posted by Rocket

Sounds good I already have a 5 pack of the 250ma fast on the way, if I have nuisances and the readings look good perhaps I will try the 250 slow. How often do you have nuisance blows? and did it get any better with the line voltage regulation?

What are you thoughts of them ups battery backups? I currently use a few of them I kept my stuff on. Surprisingly the power doesn't seem that bad around here and it rarely has to kick in. I have noticed that I run a little on the high side around 121vac here. I will have to get out the meter and kick on the fridge and AC to see if I notice any drop in voltage.

like he said, a UPS wont help, but a Line Conditioner will, if you were really willing to spend the $$$ for it..

they work by converting the AC in to DC then back to stable AC, so no fluctuations in make it out.
example
https://www.amazon.com/Tripp-Lite-LC.../dp/B0000514G8

[Rocket]

Originally Posted by Electronic M

There probably would be a noticable improvement in life. To be honest untill the CTC-2 (I ranout shortly before that) I had been using mostly fuses from electronics I had been scrapping and hadn't checked if what I had was slow blow or not.

BTW: line voltage affects these a good bit. There are usually 2 line voltage taps on the transformer primary on most RCAs having it on the best tap for your line voltage or even runing the set off a variac set for balance between normal picture and minimum H output cathode current is not a bad thing to do.

Couple of other things you can do are to make a ventilation hole in the HV cage and mount a small fan to draw warm air out to cool the flyback. Also on the CTC-16 I serviced for a dead beat (guy still owes me money) that used to be active here. He wanted me to remove the rubber tire on the HV winding and replace it with Silicone based on this video: https://www.youtube.com/watch?v=BUnPkymnxUw which I sucessfully did for him. Apparently the rubber beraks down and becomes conductive sometimes as it ages.

I will keep on eye on the fuses and the power draw and report back how well it goes.

Thats good to know about these sets. I think it may be worth it even if my line voltage isn't as bad it still would be better from what I've taken notice here the last few days.

I really like the idea to ventilate the flyback cage, I've been thinking about doing that as well. I really would like to do what I can to keep the flyback good. I can't believe that they put a tube in a metal box with the flyback, its gotta get pretty hot in there. I did notice though that the tube says it has X-ray radiation and perhaps maybe that's why they have it in a cage. I wonder if there would be X-ray leakage with drilling in some holes at the top that one would be concerned about

Is there any signs when the rubber becomes conductive and becomes a problem? I may give it a shot in the future and try to do that as well. Really sucks someone didn't pay you for your work, that's the worst.

[Rocket]

Originally Posted by Yamamaya42

like he said, a UPS wont help, but a Line Conditioner will, if you were really willing to spend the $$$ for it..

they work by converting the AC in to DC then back to stable AC, so no fluctuations in make it out.
example
https://www.amazon.com/Tripp-Lite-LC.../dp/B0000514G8

Thats a pretty nice line conditioner, I believe you and Tom got me convinced : D lol and from keeping an eye on things around here, it could probably use it. I was about to look up how exactly it works as well hehe

I am now curious what the efficiency of this unit is converting ac to dc and back to ac again.

[Electronic M]

Something akin to these is what I use. https://www.alliedelec.com/circuit-p...20Stock%20Only

The way I understand it there is a motor run cap inside that regulates the power through a resonance effect. They can hold outut voltage rock stable with anything between 90-140 input...Heck they can even hold stable output voltage through a missing cycle or two of input.

I see new ones are stupid expensive...I got all of mine by haunting Hamfests and antique radio swapmets...I don't think I paid over $25 a pop for mine. Every one of the 4 I've got was a good purchase, and I'm still lookin for more.

The advantage of a CVT is there is no switch mode supply to potentially generate RF hash on the line...Also fewer parts means less to go wrong.