CTC16 Flyback Cooling

[Fant]

I use thermal joint compound or grease to aid in heat transfer from transformer frame to TV chassis.

[andy]

...

[Findm-Keepm]

Originally Posted by andy

Most RCAs have a high line voltage tap on the power transformer. There may be a switch, or it may just be tied off under the chassis. Selecting that should help a lot.

The CTC16 sets lack the line adjust switch - hence the variac. Nick (miniman82) runs all of his sets on a variac - I have a Sola conditioner that brings my high line voltage down, but only to my bench, so I use my VIZ Variable (metered) Isotap to bring it down for my CTC16 when I want to operate it.

As to the cathode current, 250mA is the absolute max, and no, I've never seen one run that high. At 110V, my CTC16 runs right at 200 - I remived the focus rectifier current from the flyback load, and will probably do the same for the 3A3, all in keeping the fly healthy.

Given the dearth of available flys for pre-CTC38 sets, there ought to be a "flyback health manual" we could create - lots of sets turning up that can be restored with the existing fly, and threads like this illustrate the need. Zeno, OldCoot, miniman82, andy - could all contribute greatly.

[andy]

...

[old_coot88]

Originally Posted by andy

Most RCAs have a high line voltage tap on the power transformer. There may be a switch, or it may just be tied off under the chassis. Selecting that should help a lot.

If present, the two tap points are on a terminal strip under the chassis, just under the power xfmr. Sets with the tap came wired for 'low' line voltage, and needed to be set for 'high'. It was SOP after uncrating.

[walterbeers]

Originally Posted by Arcanine

So it looks like Tom (Electronic M) has brought life back to my CTC16 that I regretted buying. I was so mad about it I didn't even want to touch it. Long story there.

The one thing I noticed, and Tom did as well, is the flyback get's very hot after awhile and starts to drip wax. This is about after an hour on for him, and an hour on for me when I noticed it was hot. It's set correctly and Tom will chime in on that, or you can check the last parts of the CTC16 thread and see.

Do RCA Fly's just run really hot? And if so, would it hurt anything if I cut open the flyback box and installed a small computer fan to it externally, to suck cool air though the box so the Fly isn't sitting in there melting it self to death?

I was also thinking of putting a small computer fan on the top of the HV cage in my 1954 CTC2B, 21CT55 21 inch color. I don't see where it would cause any harm. Yes, I have always thought that around 210 ma was about the max that the cathode current should be at. The HV cage on that old set is completely enclosed except for a hole in the top with a "chimney cap", in which I could install a fan. Possibly the reason that HV cages as so tightly enclosed it to reduce x-radiation.

[Phil Nelson]

Originally Posted by walterbeers

I don't see where it would cause any harm.

A little cooling can't hurt, if you don't mind the noise. I tried a little fan inside the back of my Predicta barberpole set, but quickly took it out because the noise bugged me.

Also, air carries dust, so the more air you force through an interior, the more dirt that may accumulate. I remember cleaning out old desktop computers that were plugged almost solid with dust bunnies. Those computers probably ran for more hours per day than the typical color roundie, however.

Phil Nelson

[ohohyodafarted]

Originally Posted by walterbeers

I was also thinking of putting a small computer fan on the top of the HV cage in my 1954 CTC2B, 21CT55 21 inch color. I don't see where it would cause any harm. Yes, I have always thought that around 210 ma was about the max that the cathode current should be at. The HV cage on that old set is completely enclosed except for a hole in the top with a "chimney cap", in which I could install a fan. Possibly the reason that HV cages as so tightly enclosed it to reduce x-radiation.

I did add a small fan to the HV cage on my CT55 and it made a huge difference in keeping the fan cool to the touch. I was also concerned about the noise, but I found a small low noise 2.25" fan at Mouser. Look for a fan with low noise and low air volume. I made a round hole in the side of the HV cage and connected it to the switched side of the incomming AC. You can hear it a bit at start up when the sound is not on but when the audio is at normal room volume it can not be heard at all.

The original flyback got wiped out shortly after the set was restored, and I did not want to chance that the UBER RARE replacement would get fried. So I added the fan and the flyback runs cool to the touch now.

[Username1]

If it's a good meter - the movement is far removed from the circuit, but the cap
is most likely insurance so no sharp spike makes it to the movement....
A spike that may occur if one lead is accidentally lifted while the tv is on....
It's unlikely the movement's inductance comes into play as it is bypassed by a
resistor of small value, 1 -2 Ohms, and then further hidden in a series resistor network....

But I can see that the possibility of the high frequency and unknown internal
components to the meter could cause resonance and effect the accuracy of the
reading.... So Yes I can agree on the resonance possibility....

.

[roundscreen]

OK I am confused. What else is new. Are there two threads on this ctc 16? Did Tom replace the power supply electrolytic caps? If not I would start there. A quick check would be to hook up a dvd to the set. Put it on pause and see if there is a slight wave in the picture. If you want to use the set as every day watcher, They should be replaced any way. The fly will get hot with the 3a3 sitting on top of it but you should not see wax dripping out of it. Your test pattern is really cool. Must make it a lot easier to do convergence