Flyback fire

[radio nut]

My crosley had the flyback catch on fire and destroy the entire set. Could something else have caused this fire, or is this solely a flyback issue? I did run this set about 200 hours and I figured it was free of flaws. I am asking so I can make sure this does not happen again. It has been a long standing dream of mine to have a tube tv. My crosley was it, now on my bench is a very old General electric set and I do not want another fire.Experts, please help!Thank you.

[Big Dave]

Put the set in a well ventillated place and wait a few days. It may just be a bad fly. How bad was the damage? If you could post pics, that would help. That Crosley may not be a total loss. Flyback fires were not uncommon. Based on your post, I think all you may need to do is replace the fly and clean the set up. I'm sure one of us can tell you for sure either way.

[andy]

...

[avionic]

Originally Posted by radio nut

My crosley had the flyback catch on fire and destroy the entire set. Could something else have caused this fire, or is this solely a flyback issue? I did run this set about 200 hours and I figured it was free of flaws. I am asking so I can make sure this does not happen again. It has been a long standing dream of mine to have a tube tv. My crosley was it, now on my bench is a very old General electric set and I do not want another fire.Experts, please help!Thank you.

Yep ,One other reason for enclosing them in a steel can,besides arc potential.

[Old1625]

Flybacks can get hot enough to burn if the HOT cathode current is running above recommended rating.

Were you watching the set at the time? I can't imagine a flyback transformer suddenly catching flame without getting hot enough to stink to high heaven just before that. And to say nothing about other symptoms...

[MRX37]

It's kinda funny to me that they would use WAX and PAPER in a component that has the potential to arc and catch fire. They should have went with something less combustable and never allowed flybacks made with wax and paper.

Who knows how many fires might have been started by one of those flybacks...

[RetroHacker]

Originally Posted by MRX37

It's kinda funny to me that they would use WAX and PAPER in a component that has the potential to arc and catch fire.

Actually, both of those materials are excellent insulators. And, remember, sixty years ago, modern synthetic epoxy resins did not exist.

Flybacks can catch fire, this is true. But, aside from making a lot of nasty smelling smoke, they shouldn't cause much else to catch fire. The chassis is made from metal. And I seriously doubt that a burning flyback would be able to make a large enough (or hot enough) flame to be able to catch the inside of the cabinet on fire.

A larger problem with the old wax and paper components (flybacks, capacitors), isn't so much that they could theoretically catch fire, but that they have a tendancy to be affected my moisture. The wax/paper combination is OK at sealing out moisture, but not as good as, say, plastic. The moisture gets into the component, corrodes/breaks down the dielectric properties of the materials, and the component fails.

Wax also melts fairly easily. So, if the flyback gets too hot (caused perhaps by a HO section drawing too much current), the insulating wax melts away, then a partial short forms - then you get an arc, and burning.

-Ian

[MRX37]

Originally Posted by RetroHacker

Actually, both of those materials are excellent insulators. And, remember, sixty years ago, modern synthetic epoxy resins did not exist.

I am well aware of that.

However: metal existed, glass existed, ceramic existed, etc. Maybe even bakelite could have been used.

If there is shielding to prevent a burning flyback from destroying the TV, that's fine I guess, but the poster of this topic indicated that his TV was destroyed.

[Old1625]

Originally Posted by MRX37

I am well aware of that.

However: metal existed, glass existed, ceramic existed, etc. Maybe even bakelite could have been used.

If there is shielding to prevent a burning flyback from destroying the TV, that's fine I guess, but the poster of this topic indicated that his TV was destroyed.

The reason why flyback transformers were all gooped up with wax was as much an acoustic consideration as much as a high voltage insulator. Without the wax to deaden everything and keep the windings from moving around the coil would've sung at that infamous high pitch of the horizontal sweep until every dog in the neighborhood would go berzerk. As it was they'd sing loudly enough.

For a flyback to burst into flame there must have been something very wrong with the sweep circuitry in that set.

[Old1625]

Originally Posted by MRX37

It's kinda funny to me that they would use WAX and PAPER in a component that has the potential to arc and catch fire. They should have went with something less combustable and never allowed flybacks made with wax and paper.

Who knows how many fires might have been started by one of those flybacks...

I've seen many of them arc, and not catch fire. Fire can occur if the flyback becomes boiling hot.

But with everything properly adjusted a typical flyback shouldn't get hot enough to melt the wax--never mind vaporise, which is what would have to happen in order for it to take flame.

And with all shielding in place the chances of flame spreading elsewhere are slim.

[andy]

...

[radio nut]

The flyback was a nos replacement. I did notice that the wax was split. I had the set on and was watching it. I remember now that I did have to adjust the (magnet thing) On the pic tube neck to fill up the screen which after all this time running it seemed odd. I did a couple of things and went back to watch the tv 10 minutes later and it was on fire. The fire followed wiring and took out the Horizon. line.,width, freq, and another coil. It may be possible to buy all these coils and another flyback but I will have a very expensive set with a small book price. That is why I called it destroyed, maybe out of frustration, Doug

[mattdavala]

I've told myself to make it a habit to never leave a tube set unattended. BUT I know I get quite overconfidant and will leave it on when I use the rest room, or get a bit to eat. This story will make me think twice about leaving them on unattended for even a short time.

Glad you caught the set before it did something real serious, as in your residence going up in flames. I wish you the best of luck. Try Moyers Electronics to get another flyback, controls and coils. http://www.moyerelectronics.com/

As for the price. If you plan to keep the TV then it is worth it to buy parts for it. It makes you happy using it.

Best regards,
Matt Davala

[roundscreen]

Originally Posted by radio nut

My crosley had the flyback catch on fire and destroy the entire set. Could something else have caused this fire, or is this solely a flyback issue? I did run this set about 200 hours and I figured it was free of flaws. I am asking so I can make sure this does not happen again. It has been a long standing dream of mine to have a tube tv. My crosley was it, now on my bench is a very old General electric set and I do not want another fire.Experts, please help!Thank you.

Hay man I am sorry your set caught fire. This sort of thing can scare the crap outta ya. When you fix the GE set, Connect a ma meter to the cathode of the horz output tube and keep an eye on it for a few weeks. Also turn down the line voltage to 115vac. A 1950's black and white set should work fine at that line voltage and put less stress on the power transformer and the flyback.
Ed

[7"estatdef]

Maybe a bucking transformer maybe in order to drop the ac line a bit. It's simple and cheap. I've often thought about placing a small computer type fan to cool the HV cage. Most have the horz output,damper, and hv rectifer inside. Can get kind'a warm in there.
Terry