NEW SEGMENT: EEVsmoke #1

[EEVblog]

Let me know if you like the idea or not

[tautech]

Yeah good Dave, we all learn from someone else's fail.

Translucent cased X rated caps, the cases craze/crack with age and if there's a period of non-powered the humidity gets in and power on....POP. Seen it a few times.

[CaptCrash]

Isn't the missing part from the transistor case laying on the board?
Rather than imploding it looks like it exploded and split the package.

[rollatorwieltje]

Not sure if I still have the high res pics, but this was a APC 3000VA ups that blew up:




The transistors were Fairchild RFP40N10. Note that some of the legs are actually evaporated

[WackyGerman]

I like that .  . You re right . Connecting leds to mains and other stuff would be right in the EEVblowup section 

[tautech]

Isn't the missing part from the transistor case laying on the board?
Rather than imploding it looks like it exploded and split the package.

Quite right.
I was given a 2kW 48-230VAC inverter that came from a marine installation and it had taken a hit of saltwater after a hatch was left open.  At least a dozen of the TO-220 MOSFETS in it looked just like the one Dave shows or even worse.
Must have been a hell of a bang.

Another TO-220 in my bare (not cased) LA battery desulphater suffered some sort of short and at least a 1/3 of the plastic case went somewhere......past my ear. 

[tggzzz]

I skipped through the video until I saw the X2 film capacitor - and thought I recognise that cap, it is in a Tex 24x5 scope. So I rewound a bit and, yes I was right, it is in a 2465.

I replaced exactly that cap in my 2565 last week, but I think mine had rapidly disassembled itself a little more effectively. In my case the identical cap seen in the upper left was even more spectacular - the 1/2W 68ohm series resistor had disassembled itself very effectively, taking the PCB's prepreg with it so the glass fibre is exposed, and depositing a carbon film over a 3"x3" area of the board. The scope continued to work after the magic carbon and smoke escaped, but I didn't tempt fate by leaving it on.

Scope works very nicely since I replaced those caps and the others "hidden" on the other power supply board - which were also crazed.

[bktemp]

Those older X2 caps fail quite often with a bang. It happened to me a couple of times (TV, HP power supply).

Maybe it would be a good idea not only getting the photos but also an explanation why this happened: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

[Arjan Emm]

I  like the new segment. But jeez Dave, it's very obvious  that it exploded, not imploded. The missing bit is right in front of it, with the inprint of the die.

[tautech]

Those older X2 caps fail quite often with a bang. It happened to me a couple of times (TV, HP power supply).

Maybe it would be a good idea not only getting the photos but also an explanation why this happend: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

I've only ever seen those orange/yellow whatever translucent types fail, never the gray or white plastic types so IMO it's the case failing, the material used was not fit for long term useage.

Others experiences ?

[dexters_lab]

Those older X2 caps fail quite often with a bang. It happened to me a couple of times (TV, HP power supply).

Maybe it would be a good idea not only getting the photos but also an explanation why this happened: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

+1 yea i had one go on the power supply for an old (1980s) 8" floppy disk drive

[AmmoJammo]

Here's some smoke for you...



I saw the internals of the amp later, it had melted half the aluminium clamps that held the mosfets to the heatsink....

When you have a battery bank that can supply 1000's of amps, things tend to go wrong

[Ivan7enych]

Maybe it would be a good idea not only getting the photos but also an explanation why this happened: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

Agree.
It's interesting to see why that happens, what should I avoid in my circuit. (I like education style of your videos.)

I think much better would be to reproduce the "magic smoke" on your video. For example make a simplest circuit with a transistor turning on a relay coil (without reverse protection diode), and allow a reverse voltage peak to destroy the transistor...

[Stupid Beard]

Maybe it would be a good idea not only getting the photos but also an explanation why this happened: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

Agree.
It's interesting to see why that happens, what should I avoid in my circuit. (I like education style of your videos.)

I think much better would be to reproduce the "magic smoke" on your video. For example make a simplest circuit with a transistor turning on a relay coil (without reverse protection diode), and allow a reverse voltage peak to destroy the transistor...

I agree with that too. I think that it's an interesting idea for a segment, but if it's just looking at photos then I think it's more suited to a forum thread.

[SNGLinks]

My HP8656B sig gen IEC mains filter. You better have the correct fuse in your mains feed when this burns up as it's before the fuse.

[jonovid]

Quote from: Ivan7enych on Today at 08:43:18 PM

Quote from: bktemp on Today at 07:01:45 PM
Maybe it would be a good idea not only getting the photos but also an explanation why this happened: Was it a design fault, did the user something stupid, or was it due to ageing of some components?

Agree.
It's interesting to see why that happens, what should I avoid in my circuit. (I like education style of your videos.)

I think much better would be to reproduce the "magic smoke" on your video. For example make a simplest circuit with a transistor turning on a relay coil (without reverse protection diode), and allow a reverse voltage peak to destroy the transistor...

I agree with that too. I think that it's an interesting idea for a segment, but if it's just looking at photos then I think it's more suited to a forum thread.

maybe some on screen video of Stress Testing of Dodgy Components.  as  like I got a batch of TO92's from China. As the pins unknown to Me was BASE, EMITTER , COLLECTOR   not COLLECTOR ,BASE in the middle  then EMITTER .

[setq]

Surprised they weren't base, base, smoke emitter.

Good section. I like it!

X2 film caps I don't like. My old Telequipment scope blew one a few years ago and filled my bench corner with smoke. They go out in style and cause much worry. Fortunately easy to fix!

[bktemp]

maybe some on screen video of Stress Testing of Dodgy Components.

Most semiconductors fail short circuit without any sparks, so it will be quite boring.
I don't think we need another Youtube channel blowing up circuits or components. Photonicinduction already did a great job in applying to much voltage to almost everything until it pops. Mehdi Sadaghdar (ElectroBOOM) also has sparks on most of his videos. They are always fun to watch.

Explaining why it did happen and how to avoid it is probably more adequate for Dave's typical audience, because they are interested in learning things.

The most spectacular failures are probably in mains powered circuits, because there you have large caps after the rectifier charged to 160V or 320V. Those caps can deliver many 10 or 100kW for a short period of time and vaporize almost anything.

[_Andrew_]

When it comes to smoke it has to be:   Lucas the Prince Of Darkens

This sums up the theory of smoke quite well http://hdabob.com/the-vehicle/electrical-system/smoke-theory/

[Don Hills]

Fortunately, you can get Lucas smoke replacement kits:

http://www3.telus.net/bc_triumph_registry/smoke.htm

[setq]

More Lucas thoughts: http://www4.ncsu.edu/~mtmorris/index3.html



I actually incinerated the entire ignition system on my Land Rover Series III back in the 1990s thanks to Lucas. Now that was smoke - clouds of it as the battery dumped through the entire shorted loom!

[G7PSK]

I have had many vehicles with Lucas electrics and mechanical parts, never had a problem with them now wico that is another story.

[Len]

You don't see this very often

I've seen it several times on this very forum. It's a Rifa brand capacitor, isn't it?

[maelli]

Nice segment, we want more of this!
Regarding the Rifa PME271, these are a classic for failures. The potting material appers to be too brittle, cracks form, moisture gets in.
The metalised paper winding starts increasing capacitance (good?) and increasing loss factor (sure not good).
When connected to the mains, things get ugly.
The cap on the picture has not seen voltage for years, it will go up in smoke within seconds or minutes if connected to mains ;-) should I try?

[madires]

You don't see this very often

I've seen it several times on this very forum. It's a Rifa brand capacitor, isn't it?

Not just on this forum. I've seen several cracked X2 Rifas myself, luckily none completely vaporized like in some older IEC line filters. If I see any Rifa cap, I feel the sudden urge to replace it with a Wima.