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  #16  
Old 11-24-2018, 02:01 PM
ZenithNut ZenithNut is offline
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Originally Posted by Electronic M View Post
If you have HV your fly is still decent. There are a variety of things in the HV cage that can cause that noise. First off the HV cage and the parts inside it need to be VERY clean...Even a thin hard to notice layer of dust can carbonize into a conductive path.
Second: the filament leads between the flyback and the bottom of the HV rect tube and the insulator cup around the base of that tube as well as the HV lead to the CRT and the top lead to the HV regulator can all break down and arc/ develop holes and or conductive carbon tracks fron HV side of the insulation to grounds on the outside of the insulation (I've seen and fixed these issues many times)...Examine it thouroughly with the set on and covers open with little to no room lighting to acertain the exact source of arcing, and if you clean these parts (which you should) examine them carefully.

Third (it has been a few years since I last had a CTC-25) IIRC these molded the top cap of the HV rect tube into the fly HV winding....If the HV rect tube is too physically short it will not seat properly into the cup and arc...Makesure you have one of the taller versions of that tube (different makes made them taller and shorter at different times). Also on RCAs with the HV top cap molded into the flyback there is an issue with the outer rubber tire breaking down and becoming conductive between the cup and the center of the winding. The solution is to peel off the rubber tire scrape away any carbonization beneath the tire and recoat the area the tire once covered with sensor safe RTV silicone.

Another note in the days these sets were new many people in humid climates did not own airconditioners or dehumidifiers, and these sets were designed to handle it. If the fly absorbed too much from being off for weeks/months it would heat up and boil/bake out the moisture sometimes bubbling out a bit of wax too, then normalize and continur to function...If you recoat it before letting it do this maybe leave a small breathe hole or two on the side for it to vent then seal them after it has baked out a good bit.

Also important is making sure your horizontal is set up properly the osc, needs to be adjusted properly as per the sam's proceedure, grid drive/bias at the horizontal output needs to be strong, and perhaps most importantly yout H linearity/efficiency coil needs to be adjusted for minimum H output cathode DC current. All the horizontal adjustment proceedures should be explained in your copy of the Sam's...Preform them.

RCA flys can last indefinitely if you make sure conditions around them are ideal...If they engineered a bit more margin in like Zenith did then you could afford to be more lax with horizontal maintenance.
Hey.

So I got a 0-500 dc ammeter. I have a few things to report in. Im cleaning the hv leads and cage. I am also getting ready to pull the fly cage to re silicone. One thing I forgot to mention is that I did end up loosing vertical but there was still a bit of something you could adjust with the brightness which I imagine was the horizontal.

The boost rectifier diode has gone open. It is listed as a 1n3195. Sr102/X6 has also failed. It is in series with the yellow lead going into the primary of the vertical output. Im having trouble finding a replacement for it. It is a hv rectifier and is listed in sams under General electronics GECR-2. So I will need to replace the boost rect diode and hv diode.

You suggested fusing the h output cathode with a .25 amp fuse. What voltage rating?
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  #17  
Old 11-24-2018, 05:12 PM
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Any of these should work for the boost diode. https://www.mouser.com/Semiconductor...r45Z1yopdfySGT May want to put 2 in series to ensure the replacement can take any possible voltage spike. Radio Shack used to sock a 2A 1.5KV part that I used to replace the boost on my CTC-15 but they ain't a thing anymore. Parts like diodes in sets of this vintage are probably over 3 generations obsolete so it is easier to look up the key specs and spec out a new one than find and trace forward all the missing links in the recommended successor line.

Any voltage of fuse is fine. The only spec that matters for fuses is the current. A you can take a .25A 125V fuse and put it in a device that wants a .25A 250V and vice versa and the device will work okay and the fuse will still blow at .25A current. You probably want a slow blow and not a fast acting fuse...The current averages ~200mA but spikes above 250mA for tiny fractions of each second. A fast act fuse is designed to catch that fractional spike and blow (creating lots of nuisance failure which you don't want) but the slow blow will average out the current and only blow when the average current reaches fault value.
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  #18  
Old 11-25-2018, 04:20 PM
ZenithNut ZenithNut is offline
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Any of these should work for the boost diode. https://www.mouser.com/Semiconductor...r45Z1yopdfySGT May want to put 2 in series to ensure the replacement can take any possible voltage spike. Radio Shack used to sock a 2A 1.5KV part that I used to replace the boost on my CTC-15 but they ain't a thing anymore. Parts like diodes in sets of this vintage are probably over 3 generations obsolete so it is easier to look up the key specs and spec out a new one than find and trace forward all the missing links in the recommended successor line.

Any voltage of fuse is fine. The only spec that matters for fuses is the current. A you can take a .25A 125V fuse and put it in a device that wants a .25A 250V and vice versa and the device will work okay and the fuse will still blow at .25A current. You probably want a slow blow and not a fast acting fuse...The current averages ~200mA but spikes above 250mA for tiny fractions of each second. A fast act fuse is designed to catch that fractional spike and blow (creating lots of nuisance failure which you don't want) but the slow blow will average out the current and only blow when the average current reaches fault value.
Im gonna go with this guy for the boost diode.



https://www.mouser.com/ProductDetail...%252bUjA%3d%3d

Should work well right?

Also wanting to find a sub for 1n3195 heres the data sheet. There is a NOS 1n3195 on ebay for cheap. That is also an option.

https://www.datasheets360.com/part/d...1594065512865/

Last edited by ZenithNut; 11-25-2018 at 04:39 PM.
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  #19  
Old 11-25-2018, 07:26 PM
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Originally Posted by ZenithNut View Post
Im gonna go with this guy for the boost diode.



https://www.mouser.com/ProductDetail...%252bUjA%3d%3d

Should work well right?

Also wanting to find a sub for 1n3195 heres the data sheet. There is a NOS 1n3195 on ebay for cheap. That is also an option.

https://www.datasheets360.com/part/d...1594065512865/
First one you may want to put 2-3 in series to ensure against HV spikes/arcover causing it to short, but otherwise it seems fine.


The second diode looks like a common 1N4007 should be a sub for it.

In most tube circuits the important specs for the replacement diode to match or exceed are PIV (peak inverse voltage) and average forward current. The rest usually makes little difference.
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  #20  
Old 11-26-2018, 07:11 AM
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One last thing is speed ( forgot what they called it ).
If you use a common 3A 1KV rectifier as a scan rectifier it will
blow within a few hrs because it overheats. Cant take the higher
freq. Same goes for in switching supplies.

IIRC boost diodes didnt test like a common diode ? I do remember
they rarely went bad.

73 Zeno
LFOD !


Quote:
Originally Posted by Electronic M View Post
First one you may want to put 2-3 in series to ensure against HV spikes/arcover causing it to short, but otherwise it seems fine.


The second diode looks like a common 1N4007 should be a sub for it.

In most tube circuits the important specs for the replacement diode to match or exceed are PIV (peak inverse voltage) and average forward current. The rest usually makes little difference.
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  #21  
Old 11-26-2018, 09:59 AM
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Originally Posted by zeno View Post
One last thing is speed ( forgot what they called it ).
If you use a common 3A 1KV rectifier as a scan rectifier it will
blow within a few hrs because it overheats. Cant take the higher
freq. Same goes for in switching supplies.

IIRC boost diodes didnt test like a common diode ? I do remember
they rarely went bad.

73 Zeno
LFOD !
With the virtual extinction of 60Hz linear power supplies most new rectifier diodes can handle at least horizontal rate switching. Even the humble 1n4007 is found in switch mode supplies these days. I've used many normal silicon rectifiers as boost and convergence doide replacements in tube sets had good results. The original boost and convergence diodes were selenium for fast switching...If they had the modern fast switching silicon diodes we had now back then they would have used them instead of seleniums.

Still it is not a.bad idea to convert switching time to seconds then take the inverse to get frequency and make sure that frequency is higher than that of the waveform applied.
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Last edited by Electronic M; 11-26-2018 at 10:04 AM.
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  #22  
Old 11-26-2018, 06:42 PM
ZenithNut ZenithNut is offline
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Quote:
Originally Posted by Electronic M View Post
First one you may want to put 2-3 in series to ensure against HV spikes/arcover causing it to short, but otherwise it seems fine.


The second diode looks like a common 1N4007 should be a sub for it.

In most tube circuits the important specs for the replacement diode to match or exceed are PIV (peak inverse voltage) and average forward current. The rest usually makes little difference.
I went to my local electronics shop and picked up a 1n4007 and a 1n5408 for the replacements
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  #23  
Old 11-27-2018, 10:59 AM
ZenithNut ZenithNut is offline
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Electronic Memory.

Ive peeled the brown tire off completely. Theres this rubbery kinda pink stuff under it. I imagine that has to go too right?

There are no visible signs of conductance on the tire of the fly. There is one tiny spot where one spec of the winding is exposed but I think that only happened peeling the tire off.

Of course ive successfully removed the fly cage for cleaning too. I have almost everything short of a fuse and fuse holder I forgot to get when I was in town.
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  #24  
Old 11-27-2018, 11:26 AM
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That pink stuff is silicone. If it is blackened or loose pull it off, otherwise it is fine to leave it be.

If you exposed the winding then you may want to check continuity before applying fresh silicone... if you somehow nicked a lead open it will be much more of a pain to find and fix after you coat it.

BTW if you want to see the process of coating it I have pics of a CTC16 fly I did a few years ago in a thread here on VK. Shango66 on YouTube has some videos of this too.
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Last edited by Electronic M; 11-27-2018 at 11:33 AM.
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  #25  
Old 11-27-2018, 11:53 AM
ZenithNut ZenithNut is offline
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That pink stuff is silicone. If it is blackened or loose pull it off, otherwise it is fine to leave it be.

If you exposed the winding then you may want to check continuity before applying fresh silicone... if you somehow nicked a lead open it will be much more of a pain to find and fix after you coat it.

BTW if you want to see the process of coating it I have pics of a CTC16 fly I did a few years ago in a thread here on VK. Shango66 on YouTube has some videos of this too.
I ohm"d out each winding ie 1 to 2, 2 to 3, and so on. Everything was in spec. Looks like a piece of wax paper came off with the silicone.

All the loose old silicon is gone. So ill look at your thread.

Btw I love shango066 s channel.

I dont know if this was the source of hissing but the non painted metal shield surrounding the 6el4 shunt regulator, there is a clip to hold the hv leads and theres a "shadow" almost burnt into the metal. As in its really clean were the leads were resting against and browned on the edge.
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  #26  
Old 11-27-2018, 01:15 PM
ZenithNut ZenithNut is offline
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Originally Posted by Electronic M View Post
That pink stuff is silicone. If it is blackened or loose pull it off, otherwise it is fine to leave it be.

If you exposed the winding then you may want to check continuity before applying fresh silicone... if you somehow nicked a lead open it will be much more of a pain to find and fix after you coat it.

BTW if you want to see the process of coating it I have pics of a CTC16 fly I did a few years ago in a thread here on VK. Shango66 on YouTube has some videos of this too.
Im having trouble finding your thread. I have all the old silicone off. I imagine im hust gonna put a nice even layer on right?
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  #27  
Old 11-27-2018, 02:21 PM
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Pretty much.

It is this thread for what it's worth http://videokarma.org/showthread.php...=CTC-16&page=6 Some of the pictures are gone... IIRC I deleted them to make room when my Photobucket filled back before they instituted hosting ransom... Normally I try to preserve resto info I post but the cat I did that work for flaked out on payment he owed and I was a bit angry.
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Last edited by Electronic M; 11-27-2018 at 02:47 PM.
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  #28  
Old 11-27-2018, 03:39 PM
ZenithNut ZenithNut is offline
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Pretty much.

It is this thread for what it's worth http://videokarma.org/showthread.php...=CTC-16&page=6 Some of the pictures are gone... IIRC I deleted them to make room when my Photobucket filled back before they instituted hosting ransom... Normally I try to preserve resto info I post but the cat I did that work for flaked out on payment he owed and I was a bit angry.
I have the sonic the hedgehog blue silicon evenly smoothed over the fly. The new diode has been installed, and ive disconnected the cathode (pin 3) of the h output tube from ground. I soldered a jumper from ground to the top of the chassis and another jumper to pin 3. My am meter will go imbetween these two points.

To be honest im sorta nervous about this. I just really wanna see it work. Ive worked on a zenith bw tv set and successfully restored both my fisher tube receivers. I think im nervous cause its color.

I know the silicon isnt really conductive when its wet but it is drying. Will be ready to fire up soon
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  #29  
Old 11-27-2018, 07:15 PM
ZenithNut ZenithNut is offline
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Pretty much.

It is this thread for what it's worth http://videokarma.org/showthread.php...=CTC-16&page=6 Some of the pictures are gone... IIRC I deleted them to make room when my Photobucket filled back before they instituted hosting ransom... Normally I try to preserve resto info I post but the cat I did that work for flaked out on payment he owed and I was a bit angry.
I hooked everything up and the cathode current steadily rose up to 200ma and then kept going towards 300. I unplugged the h output cap and it dropped to around 40ma. If i touch the h output cap to the tube it goes up towards 300 but then it started backing down to around 250. Tweaking the hori linearity coil had some effect. If I touch the plate cap you can hear the hv jumping. My tube tester doesnt test compactrons so I sont know if its shorted or not. I might have an extra. I had all the controls turned down so I dont know if there was anything on the screen.

No smoke from the flyback and theres hv
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Old 11-27-2018, 07:16 PM
ZenithNut ZenithNut is offline
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*im not sure if the h output tube is shorted.

It got really freaking hot too
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