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  #16  
Old 10-25-2010, 10:40 PM
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Some of you need to take a deep breath and chill out. It's just a damn piece of equipment. Tomcomm's set may have ran at that current for 50+ years with no problem. But folks, it is a 55 year old transformer, and sorry, but sh*t is bound to happen. No one engineered these parts to operate a half century into the future. Furthermore, it's his set and his money and the idea of denying him the right to buy a replacement part (or do penance for that matter) is childish and ludicrous.
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  #17  
Old 10-25-2010, 11:30 PM
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Correct me if i am wrong is your CTC2B the same as the CTC2 in the CT 100 that uses a 6CD6? if so according to the RCA receiving tube maual RC-21 "the average cathode current............... 200 max ma" . Whats up with 3R264?
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  #18  
Old 10-26-2010, 12:09 AM
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The CTC-2B uses a 6CB5 which is spec'd for a design center maximum cathode current of 220 ma. Having said that, count me among those who aren't particularly sympathetic...or surprised.
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  #19  
Old 10-26-2010, 12:09 AM
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Quote:
Originally Posted by AUdubon5425 View Post
denying him the right to buy a replacement part is childish and ludicrous.

The idea that anyone here could deny anyone else on this forum anything is what's ludicrous, taking someone's OPINION for fact is also childish...


That said, it is my OPINION that this thing burned up because of the 'mods' that were done to it. Maybe it's just me, but when I read things like:

'I intend to start reducing the CRT Ultor HV from its present 34KV....'

and

'I jacked up the +400v B++ supply to above +420v'


I get a certain 'cringe factor', know what I mean? Not only was the 21AXP22 never rated for that votlage, but I severely doubt the flyback liked being driven that hard. How many times do we see people get warned again and again about HOT current, recapping, variac starts and the like? Seems obvious to me that the experimentation took it's toll, that's all I'm saying. I do hope the set can be fixed, but as I said I don't think you're likely to find an NOS one.

Some of you collectors are certainly a strange breed...
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  #20  
Old 10-26-2010, 12:58 AM
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The burden is on us,the keepers, the possessors. We must be good stewards of the rare and dimminishing.For every one good thing we do to preserve something there is at least five things we can do to destroy it.
No amount of chastisement from others could ever reach the level punishment that i would inflict on myself for hurting precious treasures.
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  #21  
Old 10-26-2010, 02:16 AM
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Originally Posted by miniman82 View Post
The idea that anyone here could deny anyone else on this forum anything is what's ludicrous, taking someone's OPINION for fact is also childish...
You know, what the guy needs is constructive criticism and advice such as the replies from andy and kx250rider. Suggesting he doesn't "deserve" another flyback is asinine. Period.

Quote:
Originally Posted by Red Raster
No amount of chastisement from others could ever reach the level punishment that i would inflict on myself for hurting precious treasures.
Three days ago I watched someone drive a pick axe into the side of an NOS Sylvania color combo with a dead CRT. Guess I should have thrown myself between them. Hate to tell you, but not long after we draw our last breath most of our "precious treasures" will probably be scrapped for copper.
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  #22  
Old 10-26-2010, 02:43 AM
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Not until they pry them from my cold dead fingers and of those who will continue after.
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  #23  
Old 10-26-2010, 02:51 AM
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Quote:
Originally Posted by ctc17 View Post
I know this is a long shot, but, how about rewinding? Has anyone ever successfully rewound a fly or had it done by a transformer company?
Hi,

some years ago, I visited Marcel van Grinsven in s'Hertogenbosch. He had manually rewound the primary coil of a burned flyback for a 90° Delta shadowmask color tv set. The rewound flyback looks lousy, but it worked! I saw the set working with this flyback.

Meanwhile, he could replace the rewound flyback with a spare one.

I learned that rewinding a primary coil seems not as difficult as it looks like. The reclacing of the EHT coil with a coil from an other flyback model is much easier since the technical values are more similar. I have even replaced a Sojvet EHT coil for a coplor flyback with a ten-years older German EHT coil of a quite different color tv set.

Kind regards,
Eckhard
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  #24  
Old 10-26-2010, 03:22 AM
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Quote:
Originally Posted by AUdubon5425 View Post
You know, what the guy needs is constructive criticism and advice such as the replies from andy and kx250rider. Suggesting he doesn't "deserve" another flyback is asinine.

This is the last thing I will say on this, since I already clarified what I wrote:

I NEVER SAID ANYONE DID OR DID NOT 'DESERVE' (your words) ANYTHING. Stop putting words in my mouth, or meaning to my posts that does not exist. If you want to get butthurt about something I've posted, send me a PM. I don't sugar coat reality, I call it like I see it. My first post was my initial reaction to reading OP's post. My second reaction is: I'm not surprised it blew up. You're free (as I am) to give whatever advice you wish, if you have some issue with me personally contact me, and if that doesn't work, a mod.


Quote:
Has he considered getting professional help with his obvious anger management problem?

I kill terrorists for a living, what's your release?
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  #25  
Old 10-26-2010, 09:04 AM
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Quote:
Originally Posted by yagosaga View Post
Hi,

some years ago, I visited Marcel van Grinsven in s'Hertogenbosch. He had manually rewound the primary coil of a burned flyback for a 90° Delta shadowmask color tv set. The rewound flyback looks lousy, but it worked! I saw the set working with this flyback.

Meanwhile, he could replace the rewound flyback with a spare one.

I learned that rewinding a primary coil seems not as difficult as it looks like. The reclacing of the EHT coil with a coil from an other flyback model is much easier since the technical values are more similar. I have even replaced a Sojvet EHT coil for a coplor flyback with a ten-years older German EHT coil of a quite different color tv set.

Kind regards,
Eckhard
I would like to second this idea - if the primary winding is separable from the secondary. The primary winding depends mainly on its inductance for proper operation, since the distributed capacitance is not that large, plus, it is essentially in parallel with the yoke inductance. The secondary (HV) winding is tuned by its distributed capacitance, which means you need the same materials as well as the same winding configuration to get the original result in rewinding the secondary. Using an existing good secondary coil in case that has failed also makes sense, since you will get both the designed inductance and distributed capacitance.

I wish the OP good luck, but also want to say that I personally never would raise the B+ , HO current or HV to improve the picture. HO and HV stages are just designed too close to nominal to do that IMO.
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  #26  
Old 10-26-2010, 10:14 AM
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Zenith26kc20 Zenith26kc20 is offline
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This may be a dumb question but I'm curious.
Have you tried removing the high voltage winding (physically) and running the set without the winding to see if the current rises after a few minutes? On most failed flybacks I have encountered, the secondary breaks down and burns up. This could leave the primary and the pulse windings intact (could I say).
If this is the case, trying just the high voltage winding from another flyback may be the cure.
I "hot rodded" a Magnavox solid state years ago with great results. It died from a shorted (AC hot to chassis) FM tuner which I temporarily connected into the system (stereo and TV all together) and fried the TV and preamplifier.
My two cents.....
I am sorry to hear of the flybacks demise.
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  #27  
Old 10-26-2010, 11:47 AM
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I've had success with bad flybacks by doing the following. Remove the high voltage winding, leaving only the primary windings. Fire up the set. If everything appears to work (other than no HV, of course), get a solid state HV tripler of the type used in later color sets. Connect it to the Hor. Output plate and the chassis to produce the HV.

Might not work on your set, but it is an easy and cheap fix if it does, until you can find a replacement flyback (or talk John Folsom into winding one for you!)
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  #28  
Old 10-26-2010, 12:44 PM
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Quote:
Originally Posted by Eric H View Post
The Mona Lisa is a "Priceless object" a Flyback is just a TV part.

Someone simply asked for help, lets keep the rude replies in check shall we?
Yes. I've been a member here for a few years, and I don't remember any case like this where other members "ganged up" on another. Not shame on Tom; but shame on the shamers.

There are at least two AKers in this thread, who are lucky Eric and the other mods are tolerant, and lucky that I'm not a moderator here.

Charles
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  #29  
Old 10-26-2010, 01:49 PM
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Unfortunately, Tom's flyback suffered a catastrophic internal short in the primary winding. The heat generated actually caused the HV winding to slump. But there is still some hope. His flyback is in a box beside my workbench. It has been partly unwound, and the winding "recipe" recorded. I have not yet unwound the HV winding. This flyback is a bifilar wound type, with most of the primary and secondary windings wound with two wires in parallel. This makes it that much more difficult to attempt to rewind. The HV winding is a single strand of approx. AWG 38 wire.

I have wound 2 color flybacks so far, one for a 15" Motorola color set, and one for a CT100. The Motorola flyback works, but it has lower impedances than the original, and has a big "dip" in the top of the flyback pulse, which is causing some issues with the gated circuits. So just having the winding turns count recipe is not all there is. More experimentation will be required to attempt to determine what parameters need to change. As for the CT100 flyback, it too measures lower in inductance than the original, and if failed almost immediately upon installation in the set. Unwinding it did not reveal an obvious defect. I suspect wire handling is a critical issue.

I have taken a break from coil winding attempts for the last couple of months, it is just too darn hot out in the garage to slave over a hot winding machine. And other project have managed to get on the bench ahead of the coil winding. But in the next month or so I will get back to it, and see if I can make more forward progress.


Here is a photo of the winding machine, a George Stevens model 225-AMVP universal progressive coil winding machine, made in 1964. Some of you may have seen this at my ETF presentation on coil winding.

I will report progress as it is made.
Attached Images
File Type: jpg WINDING A HV COIL 1 A.jpg (118.7 KB, 153 views)
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  #30  
Old 10-26-2010, 04:26 PM
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Quote:
Originally Posted by miniman82 View Post


I intend to start reducing the CRT Ultor HV from its present 34KV....'

and

'I jacked up the +400v B++ supply to above +420v'


I get a certain 'cringe factor', know what I mean? Not only was the 21AXP22 never rated for that votlage, but I severely doubt the flyback liked being driven that hard. How many times do we see people get warned again and again about HOT current, recapping, variac starts and the like? Seems obvious to me that the experimentation took it's toll, that's all I'm saying. I do hope the set can be fixed, but as I said I don't think you're likely to find an NOS one.

..
I have to put my "2 cents" in here too.
I agree that the "turbocharging" is likely what killed the FBT.Going to OVER 420V on the B+?? If it was MY set...and I wanted to put silicons in I would have put some "series resistance" in line with the diodes, say, 50 ohms/10 watts or so. This would have kept the voltage from going over the limit.

And...34 KV?? Man...that is HIGH Voltage!! I have worked for a LONG time on tv's and I have only seen a FEW sets that high, such as a FEW sony prjoo sets, and a couple of 36" CRT's, that were 35KV. Most others are UNDER 34KV. And ALL sets with chassis tubes were under 28KV, to the best of my knowledge!! I would NEVER DARE to run a 21AX at 34KV--I would be afraid that it would kill it, and if not-- some REAL X-rays would no DOUBT be produced--since those tubes did NOT have x-ray protection.

Having said this--your experiment DID produce a BEAUTIFUL picture--like I could not BELIEVE!! No doubt the super--HV and boost had something to do with this.

IN short--I look at it like a turbocharged engine--and an OLD one, at that. Say--putting a 12 PSI boost on an old Chrysler 2.2L--and SURE you WILL get a LOT of power and performance out of it-- probably 250HP--for a SHORT time...but not for LONG--as the old engine(or fly and CRT) will NOT stand it.

Once you get the set working again...I would suggest series resistance with the diodes to get no more than 390 volts, and no MORE than 26KV h.v., and NO MORE than 225 MA Cathode current.

As for the "discourse" I agree some of it was a bit "heated", but as it was pointed out--CTC-2B sets are RARE--and the "keepers of the flame" do ANYTHING they can to PREVENT them--or parts like FBT"S-from ENDING UP IN FLAMES, and thus--allowed their passion for their collecting hobbies to steer the discussion. Myself, I have a CTC-5, and it is NOT working yet--as I have little time to mess with it, working and all--but it DOES have and a near--perfect, CR-70 tested, CRT--and the fly looks good--and when I DO "get into it" I will NOT "stress things at ALL.

I DO hope you are able to get your set going again though. Best wishes to you.

Jack.
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