Fire!

[ctc17]

The CFLs have a fusable resistor that opens when it burns. When the bulb hits end of life the current increases till the switcher burns up, basically their failure mode is smoke.
We had a power surge here several years ago and all the CFLs that were on at the time basically exploded into sparks and flame.
CFLs are bad news, do not leave unattended unless they are contained in a fixture.

[llcvt15]

I worry reading this not so much as if I fall asleep with my old Magnavox on (which I do often-- oops (at least the converter box shuts off after two hours and the raster on the screen is usually loud enough to wake me up) but more because I have a collection of old electric clocks plugged in thru out the house, every once in a while I'll hear one running a little loudly as if it needs more oil, and they do get hot to the touch running continuously...

[Tom Albrecht]

I do a lot of restorations for other people, and one modification I always do is to put in a line fuse. Stories like this one make me glad that I do. I also advise people never to leave antique sets running unattended.

I saw a newspaper article from Germany a few years ago where a house fire was caused by an antique radio. German radios usually had a line fuse, so even that will not provide 100% protection.

[old_coot88]

We had a traded-in record player in the shop one time, a cheapie 'portable' with crystal cartridge, 50C5, 35W4 and motor winding in series with the heaters, and no fuse. Filter cap was a typical cardboard tubular 50/30-150V, and it was overheating. Since the phono was basically junk anyhow, the decision was made to give it the run-to-destruct test. In 15-20 minutes or so the cap was bubbling and smoking, and then caught fire, the flame augmented by the waxed cardboard. The 'fusible' link in the 35W4 never let go.
And to think if that were in someone's house and left running unattended.

And there was that big flap with RCA CTC-25 color sets whose AC switches were catching fire and a few houses even got burned down. (Possibly some CTC-16s and 17s were involved, but much more rarely.) There was a big field refit program where the factory sent all service dealers refit switches that couldn't arc. We refitted a mess of 'em preemptively.

It can never be over-emphasized: Never, ever leave a vintage color set, B&W set, radio, or even a phono running unattended. Not even for a minute.

[Eric H]

Some years ago (10?) I left my 1955 Magnavox Regency Phonograph (with all it's original caps) plugged in and turned on for a day or two, I finally realized it was on because it heard a little bit of static coming from it.
Fortunately nothing happened but it scared me a bit.

[Zenith26kc20]

I've had a number of Zenith 9-160 modules where power supply connections caused severe scorching of the card board undereath and some cabinet damage. The flameouts I've seen where usually a fire gets going were big early, (200+ watt per channel) solid state amplifiers. The emitter resistors explode into flames when the output transistors short. I sat and watched one at a customers house burn on one channel and then the other channel after it burned a while. The customer was horrified.....
There was no real danger of catching the house on fire as it was on a custom stand that prevented anything under burning. It was weird entertainment.

[zenith2134]

Zenith26kc20 makes a good point...those early SS monster amps can cause many fires...one way they did it was to 'go DC' and set the woofers in the loudspeakers ablaze....NOT good! Thinking of Hafler, Phase Linear, Sansui, and others.

I make a point of never leaving my tube gear on when I'm out, but I have done it (modern hifi amp mostly, a Rogue Audio integrated EL34) but then again i retrofitted the stereo cabinet to have a 12v computer fan whenever the amp is lit... and the thing has 6 fuses total...one per output tube, a b pos fuse and a main fuse.

As far as the tv's, i never leave em on since my grandma used to tell a story of their tv going on fire as my grandpa was asleep in front of it one time..."hey why the hell are you making toast in the middle of the night?!" --- It was an un-identified early 70s color set...probably a hybrid

[Dave S]

Originally Posted by Tom Albrecht

I do a lot of restorations for other people, and one modification I always do is to put in a line fuse. Stories like this one make me glad that I do. I also advise people never to leave antique sets running unattended.
I saw a newspaper article from Germany a few years ago where a house fire was caused by an antique radio. German radios usually had a line fuse, so even that will not provide 100% protection.

I always put in a line fuse. Also a three conductor grounded line cord. Some concessions to strict "originality" just seem obvious to me, especially when the set will be used by a non-technical person. One thing I *usually* do when restoring a vintage set (although sometimes I manage to forget) is to break the center tap connection to ground on the power transformer and install a small fuse in the circuit. The reasoning, as I was taught, is that an overcurrent in the B+ can damage the power transformer without drawing enough current to blow a fuse in the primary. I usually install a fractional amp fuse greater than or equal to about twice the maximum design current draw. I've never figured out how to account for the surge current as the filters charge, but I've never had a problem with that. Perhaps a timed relay that shorts out the fuse for a few seconds when first powered on then opens would be a good enhancement. But I've always been taught that a line fuse wasn't foolproof protection.

[Dave S]

Originally Posted by wa2ise

I've salvaged electrolytic caps from dead CFLs that did not fail so spectularly. Got 2 15uF at 250V 105C caps from one yesterday. Yes, I tested them, as I know these can lead hard lives. The bulb blew one of its filaments, and it looks like the electronics were fine. And got 4 1N4007 diodes out of it too, tested fine.

I wrote an article a while back about this for our club newsletter. People were surprised that they could get "free" restoration parts this way. The caps rarely seem to fail in a CFL circuit. They make great filters for AA5 receivers. The diodes are useful items too, if you can deal with the short leads.

But CFL fixtures have been sort of "exhibit A" for me in terms of contained danger. I've had any number fail (virtually all of them far sooner than the claimed life span!) but although some of them smoked, and most of them scorched the housing of the base, none of them failed with any external sparking or flames. Likewise with any previous vintage electronic equipment failures I've seen. Seeing how many stories you guys have about fires makes me realize I've just been lucky.

I "always" turn off vintage equipment when I'm done with it, but of course there've been times when I forgot and left a radio or record player, or worse yet a TV or a piece of test equipment (especially easy to forget) on overnight. Like I said, I guess I've been lucky. I guess we're gonna fuse all the working artifacts on display in the museum. Now just have to figure out how to account for human failure, the "forgetting" to turn it off part...

[mbates14]

ive only watched 2 CFL lamps fail. one of them failed with open filament, watched the opposite filament start glowing, then quit. that was it..

the second one was working and POP, smell of carbon/sulfur and it went out. the ballast driver transistor had shorted/blown.

Then ive seen those cheap chinese flea market ones fail in short order, disassembly has revealed those capxon caps popped.

[Electronic M]

I just remembered an ammusing incident from a few years back.

I had bought a cool looking 60's GE toaster with a mini oven on the bottom at a garage sale a few months maybe a year back from this incident. It was around 8 years back, and I was about 12. We were running late for picking Dad up at the airport, and Mom gave me two options for fixing my self a snack (or was it breakfast), and the more apealing one involved draging out the toaster (which had been put away for some reason porbably related to trying to sell the house) well I set it up and ran it. The wireing in the kitchen buzzed ( granted this was an old house with very old wireing and I could hear the wireing buzz when every thing was turned off sometimes, but this was much louder than normal). The Toaster finished toasting while I waited impatiently (and somewhat nerviously) watching it, and as I was waiting for it to cool down enough for me to retrieve my meal the buzzing continued.....And suddenly POP! PFFSFSFSFSSFSSSSSSH! The cord exploded into a crimsion flame that was a dead ringer for the morning glory sparklers my friends and I would light on summer nights. Along with the flame there were sparks all of which came from the cord at the point that it entered the molded on plug. My first reaction after the I realized what was hapening (I feel was very brave) I grabed the cord and yanked it out of the outlet! It was a miracle the plug came with as one of the wires was completely evaporated from the plug to about 1/4" away, and the cord end of the melted lead had the conductor exposed. The strands at the exposed end had melted together and fused for about 2mm!

Of course the kitchen fuse never blew. :roll:

I had just changed the original outlet when we made some minor renovations to the kitchen, and I had to change the damn thing again after that because of the char marks the fire (explosion?) left on the new plastic outlet! Grr.

I supose it could have been worse though.....

[tvcollector]

I have a vintage 1981 TV set in the back room, not as vintage as 40s, 50s, and 60s stuff, but it's running constantly 24/7 for over a year now, and has given no problems..

[tubesrule]

Originally Posted by Dave S

One thing I *usually* do when restoring a vintage set (although sometimes I manage to forget) is to break the center tap connection to ground on the power transformer and install a small fuse in the circuit. The reasoning, as I was taught, is that an overcurrent in the B+ can damage the power transformer without drawing enough current to blow a fuse in the primary. I usually install a fractional amp fuse greater than or equal to about twice the maximum design current draw. I've never figured out how to account for the surge current as the filters charge, but I've never had a problem with that. Perhaps a timed relay that shorts out the fuse for a few seconds when first powered on then opens would be a good enhancement. But I've always been taught that a line fuse wasn't foolproof protection.

Keep in mind Dave that unlike a solid state rectifier, the emissions on a tube rectifier will come up slowly, so there really is no power on surge to the filter caps. Going twice the rated current sounds just about right.

Darryl

[pallophotophone]

Many years ago I had Sherwood tube type FM tuner that was on when I fell asleep.

The next morning I awoke and was dizzy and nauseous from the fumes from the burned out power transformer. The stench was awful !
Why it burned out was never determined.


BE CAREFUL OUT THERE !

Pallophotophone

[Jeffhs]

Originally Posted by ctc17

The CFLs have a fusable resistor that opens when it burns. When the bulb hits end of life the current increases till the switcher burns up, basically their failure mode is smoke.
We had a power surge here several years ago and all the CFLs that were on at the time basically exploded into sparks and flame.
CFLs are bad news, do not leave unattended unless they are contained in a fixture.

I have a table lamp in which I installed a CFL about five years ago. The lamp still works. I usually leave it on from sundown until midnight or a bit later. The bulb hasn't caught fire yet. I had another CFL in my other table lamp, but it burned out (no smoke) after about five years (!). I know someone who had two CFLs in table lamps in her house; the bulbs simply burned out after several years or otherwise quietly failed.

BTW, I think the design of CFLs must be improved, and quickly, as the deadline for the phaseout of incandescent bulbs in the US is less than a year away. When CFLs are the only type of light bulb available will be no time for people to worry about these lamps setting their homes afire. I can only hope the CFLs made from 2012 forward are designed not to catch fire if they short or otherwise fail. I am surprised CFLs with the fusible resistor even smoke when they go bad -- I would think once the fuse resistor opens, the lamp would go out immediately, period, with no danger of fire, since once the resistor opens the lamp no longer receives power.

The only other thing I can figure is that the fuse resistors in these lamps are placed such that the lamps are still getting power when the fuse goes, which makes absolutely no sense. Also, I wonder why the house fuses do not blow (or circuit breakers do not trip off) when these CFLs fail for any reason. (I have a feeling that the fuse[s] on the kitchen circuits in Electronic M's residence must have been overrated if it or they didn't blow when the short occurred in his GE portable oven; after all, any short bad enough to cause the cord or plug to become red hot and burst into flames is extremely serious -- the fuse should have blown at once.) Again, the only thing that makes sense to me is that the bulbs do not draw enough power, even shorted, to open the breakers, even though a shorted CFL is like any other short in a light socket or anything else plugged into a wall socket; it should blow the fuse immediately, unless, of course, the short is very high resistance -- which I cannot see occurring in CFLs. Once one of these lamps shorts, it is, or at least should be, almost always a dead short across the AC line, which will trip any breaker on that circuit if such breaker is operating properly.