Zonked!
 

Hopefully I can save somebody else from the misfortune that just befell me. I have at least two sets that have bright CRTs with lots of life left but for their heater-cathode shorts. I searched "isolation brightener" on eBay and came across these. I bought a bagful and it arrived in the mail today. It states very clearly (twice) in the instructions something that should be stated on the auction page: "Device not to be used on older sets with 6.3V - 60 Hz power line heaters."

NOW you tell me. I also saved you the trouble of experimentation by proving that both the 'device' and its flimsy leads begin to burn up within five seconds of power being applied. These transformers are compatible only with sets that power everything from the high frequency AC derived from the flyback. Again, it would be nice if the seller clearly stated such. Live and learn.

Hey Dave,

Email him and if he doesn't include the change we'll hammer him with additional emails until he does somthing about it..

I fail to see how any proerly trained and experienced technician wouldn't know that these are for scan derived CRT supplies...

Firstly, these small transformers are hard wired into the set between the CRT and chassis and are quite small. A transformer designed for 60cps will be much larger.

Secondly, the iso-boost units that were available for sets with 60cps heaters were made with a socket at one end and a plug at the other that matched the CRT, and weren't wired in...

Finally, the seller may not have known what he was selling, and didn't realize the significance of the printed statement included with the units. This is where a properly trained and experienced tech would have been able to see clearly that these are not what he wanted.

My intention is not to offend anyone by this post, but to point out that electronic servicing is best left to professionals. It prevents damage to the equipment as well as the hobbyist.

I've heard that pitch before. Business slow is it?

You may still be able to use them:

Try wrapping a few turns of wire around your flyback core, away from other windings, and feed these transformers with that. Then use the output side of the transformer to power a tube with a heater the same voltage and current ratings as that of the picture tube, and look to see if it looks to be the right amount of heater glow. Adjust the number of turns on the flyback. And check to see if the horizontal deflection on the picture tube didn't shrink too much. If that looks good, then try running the picture tube heater off it.

FWIW, I had luck using a 600 ohm:600 ohm modem isolation transformer to achieve filament isolation on an older RCA 12" B/W with a heater-cathode short. The modem was an older 1200 baud modem, and the transformer is about a 1-1/2" cube. It worked for the time I had the set running. The back got seriously deformed by my space heater this winter and will no longer fit the set.

Dunno the frequency range of the transformer, but it had to include the lower baud signals.

Cheers,

"Let the man who hath never blown anything up cast the first stone" 2 Farnsworth 4, verse 12

Know how I restore a TV or radio? I test and replace parts that in the grand scheme of things I feel that it makes sense to replace given a certain condition. If you equated my amount of electronic knowledge to a car, it would be like saying that I can acknowledge when I suspect a car has a bad fuel pump. I can test a fuel pump. I can replace a fuel pump. But, I don't know how a fuel pump makes the car run. Exchange "fuel pump" with "2nd IF stage", or something, and there's me.

I don't know Ohm's law. I blew up my first radio at age 8, but I repaired my first radio at age 8 1/2. I also built my first TV by trash picking different sets and swapping parts until I got something that kinda worked. Think I was 11. Everything else, well, it came to me along the way.

This is, after all, a hobby. I think that anyone who tried to make a living off of restoring TVs would go broke rather quickly.

I understand what you're saying, but the concept is foreign to me.

I made a very good living as a service tech for 20+ years before moving into engineering. I began tinkering around the same age you did, and of course, I destroyed equipment in the process of my experiments. But, as time progressed, so did I, and I became a professional in the field. As I honed my skills and knowledge base (I attended electronics school), destruction of equipment became increasingly rare and my success rate was very close to 100%.

The equipment that I experimented on and destroyed in the process was often fairly common, and in some cases in daily use (like roundie color sets,) so it was quite plentiful.

It is the same equipment that I read of folks working on now. However, it is rarer and not so easily repaired or replaced if inexperienced, untrained hands begin chopping away at it. And every time a set ends up on the unrepairable pile because someone that didn't really know what they were doing got to it, to me, is very sad. It's also a part of history that doesn't exist any more.

Maybe that will help you understand how I feel about this "hobby" sometimes.

I have a few of those and the package says For Sony Trinatron Only.

I would just find a little 1-2 amp filament transformer. line to 6.3 volts. If your going to cut wires may as well give the crt its own dedicated transformer.

I believe that inexperienced hobbyists should... sszz... sszz... BOOM!... That is just my luck... never mind. :lmao:

Tom C.

If you have a selection of these filament transformers, pick one that has the lowest amount of stray capacitance to the primary and/or the metal lams. To reduce the high frequency loading that that stray capacitance may do the higher frequencies of the video signal on the picture tube cathode you could use a pair of say 10uH coils in each heater wire between the new transformer and the picture tube heater. Those Sony isolation transformers may have enough inductance to do this. Its primary coil would be one of the inductors, and its secondary the other inductor. Phasing will make a difference though. Be ready to swap the ends of its primary if the video looks low passed.

I do understand what you're saying, but I think it depends on the set in front of you.

For example, there are plenty of TVs out there with picture tubes with 6.3v heaters that are far from rare that are great to "cut your teeth" on. I personally blame the Admiral corporation for most of the deforestation of the United States ;) . At least here, Admiral combos are a dime a dozen.....you can't give them away. Then there's your garden-variety Air Kings or Motorolas from the early 50s with rectangular tubes that are the prehistoric equivalent to the Wal Mart set of today. I personally think that the split chassis Philcos are an excellent set to learn repairs on, because they're not so intimidating.

Naturally, if you've got a CTC-5 in front of you that needs repair, it's not something you're gonna want to tackle until you've got some good repair skills under your belt, and even then.....

As far as unrepairable sets, well, that's going to happen whether it's at the hands of inexperience, or Father Time. The nice thing is that the best things around are still being unearthed :)

If you want free or cheap old TVs, come up here to the Pacific Northwest. Most common are the nondescript 21" B/W consoles. Combos might as well be listed in the Free category under firewood. I suspect that most of these TVs do not get sold, even to fishtankers. The unanswered craigslist ad is their last stop on the way to the landfill.

I'm as eager as anyone else to preserve rare and unusual things, and to treat them carefully. Not everything fits in that category. I suppose the common, boring sets are part of our history, but I don't have an empty gymnasium to warehouse 5,000 unwanted TVs until some distant era when they might become interesting to somebody.

So, yeah, it depends on the set in front of you. If someone burns up a scarce or historically significant TV, that's bad. If they burn up a craigslist reject that they rescued from the curb . . . not so much.

The risk of inexperienced hobbyists wrecking significant TVs seems pretty remote. If you watch these forums, every now and then some Joe Schmoe will pipe up saying, "I found Granny's TV in the basement and it makes a white line. What now?" The first thing you'll see is a chorus of people waving their hands, telling Joe not to turn it on anymore, and to find someone experienced to help. And that advice is given even when the TV in question is a common, boring set that wouldn't fetch $25 on craigslist.

Just my $0.02.

Phil Nelson

I agree, Phil. If it's a nothing-special set that looks like Godzilla used it as a scratching post, I'm putting the plug right in the wall. I've even had one or two of such actually work. Chances are I wouldn't spend gobs of time restoring it, and not many others would either.

You can find Triad F-13-X [email protected] filament transformers online
most every week. Just look under 'transformers' or 'Triad'.
I've used them to isolate B&W CRT cathodes for years.
Cheap, works fine, lasts long time!

Cliff