RCA CTC...Something? poor HV output.

[Arcanine]

Originally Posted by Findm-Keepm

And I've used RTV many times for corona prevention before - but conductive tracking does occur, and only at high voltages - where the RTV was heat cured and paths for corona were created.

I've serviced TVs since the 70s, dealt with corona and arcing in 55KV AWG-9 radar transmitter power supplies, 16KV Conrac monitor power supplies, and solved many problems with RTV. But in my humble 30+ years in electronics, I've seen RTV'd flys fail just as often as the originals, and mostly due to the carbon tracks - their death certainly created by heat or disturbed curing. RTV has such a strong dielectric strength that 1/20" will seal against corona in a 50KV system, but one tiny (electron wide) hole is all it takes to fail. Patience and curing at room temperatures, with no disturbance for the allotted time is all that is needed for success.

Now with ATS (Activation Temperature Sensitive) silicone (similar to RTV) products, the crap won't cure without heat, and at a prescribed temperature. I've use it as well - aerospace stuff - we can't afford it - but take some good old RTV3145, the good grey stuff, simply apply and let it cure, no heat. No reason to bake out bubbles that leave a tunnel behind as they head for the surface, setting up a corona/burn path....

Remember, we're trying to save flybacks, not guarantee a kill....

But i digress, it's not my flyback.

I have my fingers cross that Tom did it well and no tracking happened.

You like the CTC16 chassis. Do their flybacks normally run a tad on the warm to almost hot side?

[Arcanine]

Originally Posted by Electronic M

I got the old silicone off and recoated the fly for the CTC-16 on Saturday. It went well, and aside from the rubber tire being charred/bubbled there were no scorch marks or carbon tracks to be found (the old silicon and fly paper were fine).



I decided not to smooth it since a rough surface has more surface area, and thus should cool better.

I gave it about 1.5-2 hours run time with the silicone still soft (which cured it nicely), and it ran like a champ the whole time.

Then I got sidetracked till last night upgrading my laptop to Windows 10 (long story).

I gave it another hour and 40 minutes on. No, arcing, no wax ooze, but the fly does get rather warm...I want to try and find some time to put 3-6 continuous hours on it to see how it holds up. When I can I'll get some heat sink compound for the fly to chassis (may also squirt some between the windings and core). I'll also try to add some vent holes and a fan to it, but I gotta figure out where and which fan (the best side to put a decent sized fan is against the side of the cabinet, and not usable).


I worked on the 20 today. I resoldered the busted coax to the color level control, and resoldered the snapped off chroma transformers.....It came on, a moment later I hear a snap and the vertical fills out. Then I proceed to adjust what I believe is the chroma osc. transformer and start to get color barber-poling.....Then another snap, raster is lost, and smoke from the area of the chroma osc. transformer. I swap the two leads I guessed the connection points to, and try to reassemble it, but the bottom has melted/warped to the point where I'm not sure that transformer is worth fixing anymore....The vertical relapsed to not filling the screen too. That CTC-20 is a real mess.

I think I'll work on something else for an hour or two to get a break from RCA color work.

I think with the CTC20 it's going to come down to sourcing good replacements for those two transformers... I wish better care had been taken when it was stored disassembled. I like the style, I may wanna buy the set back, so I'd be interested in helping seek the parts.

I'd almost be interested in coming up there and learning from you while you work a little. Learn the basics I'm missing from you, that stumped me so endlessly with the CTC16. How to read and test resistors, check voltages properly, test capacitors.

As for cooling the CTC16's flyback, I was thinking of putting a small, low voltage brushless computer fan on the bottom of the right side of the flybox (Facing it with the back of the set off), blowing in on the transformer, with a vent hole on the top left side to blow the heat out. It would only take a low voltage wall-wart to power a computer fan, which could easily be wired to the TV's cord and switch, so when the set is switched on, the fan powers on. Brushless computer fans are very quiet and move plenty of air. I have several plus several power supplies laying around that'd drive it perfectly.

I'm going out of state in a few days and I'll be gone until December 10th. so while I am gone, feel free to watch and enjoy my CTC16 all you like. Besides the warm flyback, I would certainly call it done.

Windows 10 sucks so far. If you want Windows 7 I have an unlocked installer that I can give you that updates it self and is fully featured. I'm giving you a pretty high end business grade dell laptop as a bonus for all the work you did on the CTC16. it'll have Windows 7 Professional installed on it and I'll include a DVD of the reinstall stuff for you.

[Electronic M]

Findem Keepim: I did give it around 15-25 min to dry before reassembling the cage and running it. I've never needed to use a caulk or corona dope to fix an arcing/corona problem before (previous issues I've dealt with were solved by cleaning dirt off insulators and or replacing bad HV wire). I only ran it that way because in the youtube videos by Shango66 that Arcanine pointed me to for reference Shango66 seemed to do the same thing: remove old material, caulk and turn it back on with the caulk wet....I'll remember to give it more dry time next time I need to do this. Wish I'd known before I did it....

The issue with fly warmth is that the cathode current is on the low end of the range. I don't think it's exceeding the back of the hand contact rule, but it still bugs me how warm it gets.

Originally Posted by Arcanine

I think with the CTC20 it's going to come down to sourcing good replacements for those two transformers... I wish better care had been taken when it was stored disassembled. I like the style, I may wanna buy the set back, so I'd be interested in helping seek the parts.

I'd almost be interested in coming up there and learning from you while you work a little. Learn the basics I'm missing from you, that stumped me so endlessly with the CTC16. How to read and test resistors, check voltages properly, test capacitors.

As for cooling the CTC16's flyback, I was thinking of putting a small, low voltage brushless computer fan on the bottom of the right side of the flybox (Facing it with the back of the set off), blowing in on the transformer, with a vent hole on the top left side to blow the heat out. It would only take a low voltage wall-wart to power a computer fan, which could easily be wired to the TV's cord and switch, so when the set is switched on, the fan powers on. Brushless computer fans are very quiet and move plenty of air. I have several plus several power supplies laying around that'd drive it perfectly.

I'm going out of state in a few days and I'll be gone until December 10th. so while I am gone, feel free to watch and enjoy my CTC16 all you like. Besides the warm flyback, I would certainly call it done.

Windows 10 sucks so far. If you want Windows 7 I have an unlocked installer that I can give you that updates it self and is fully featured. I'm giving you a pretty high end business grade dell laptop as a bonus for all the work you did on the CTC16. it'll have Windows 7 Professional installed on it and I'll include a DVD of the reinstall stuff for you.

If you want to buy the 20 back from me later I'd be open to that. If you want to come over and work on stuff with me some time I'm cool with that.

It did not look like there is a enough clearance between the side of the cabinet and the side of the HV box for a fan, but I can recheck. A separate PS is not really necessary. It's fairly easy to rectify the set's heater line, add a filter cap so the fan sees clean enough DC, and a small user fan switch in a discreet place.

The laptop sounds awesome! I have my own windows 7 install disc that I've used with several machines. The 10 installation was a free upgrade from 7 on my school machine, and most of the time spent was preparing the Win 7 OS for a drive image backup (closing/saving the mountain of open stuff that being on for a few weeks-months straight accumulates, moving files to external drive to shrink the size of the backup image, defragmentation, run anti-virus, etc.). With the drive image backup I can go back to Win 7 anytime, or throw the image on another drive and go between them by drive swapping.
I like Win 10 so far. The back end is better programmed and it runs better/faster on my laptop than 7 did. There are a couple of things about the look of the taskbar I dislike, but I'll fix or get over them. I also hate the change in mouse commands for photo viewer (makes reading Manga a PITA), but there should be ways around that.

BTW: I got that little Admiral going last night. It was the ion trap that was extinguishing raster. It has a funky intermittent in the tuner (I believe) that kills all reception, but it can be persuaded to work. I recapped the IF board since that was easy with the back off. It is rather dim yet so I plan to test the CRT.

[marty59]

Quote: "The HV rect tube is a RCA 3A3C the chart calls for a 3A3A....I seem to recall once reading that some variants of that tube caused arcing in the CTC-16, but I can't recall it exactly or find it....Could that be the cause?"

There seems to be some variance in the height of the tube(s) and the "C" versions may be somewhat shorter, causing issues with the tube contacting the top of the flyback. There should be enough slack/adjustability in the top cover as it sets in place but good to verify.

[Arcanine]

Any updates on this? My DM's not making it though?

I'm starting to miss it~

[Electronic M]

It is basically as I left it in the last post (started other projects and left it as is). I tried to unbolt the fly to put heat-sink compound between it and the chassis for better cooling, but the bolts holding the fly are stubborn, and after trying every safe hand tool I have and penetrating oil with no results....I decided I rather not do it than start trying things that might risk damaging the flyback. I probably should look for a high line voltage tap on the primary of the power transformer and if there is one connect it...I did not install the cooling fan (but I'll give you some fans, parts and advise if you want)...I should also try to make a line bucking transformer for you...

I sent you a PM.

[old_coot88]

The line voltage tap is easy to spot. It's on a terminal strip under the chassis, right under the power xfmr area. Look for a terminal with only one wire and nothing else going to it.

[DaveWM]

I have looked into cooling fans. The only set I have one on is a CTC-5 due to the rarity of the FLY. One thing to remember about vintage TV's do NOT leave them on unattended, even for just a few minutes. They are WAY past any expected use date and the flys were an issue even back when new. The concern I have over forced air cooling is IF the fly still manages to overheat, you will have a blow touch on your hands. The flys tend to be in a confined steel box I presume on reason was safety, as in fire containment. Adding the fan pumping oxygen to a burning lump of tar will really stoke the flames.

[miniman82]

5 flybacks are super easy to find, I have one here you want it? It's the 4's and 21-CT-55's that are near impossible to replace, in fact I'd take the fly out of my Wingate and replace it with one from a 4 if I had one to spare. A Wingate with stiff HV would be a super nice set to watch, too bad they made 'em wrong from the jump.