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Microwave Mortuary

Updated February 8, 2014

Have you ever thrown a shopping cart out of a convertible at 80 mph to observe the sparks? How about hooking up a power amplifier to 115 volts AC just to see how it craters? Your fellow engineers have done these things and more! If you have a great picture of totally destroyed hardware, or a photo of a blown circuit, send it to webmaster@microwaves101. If it gets on the web site you will receive a free Microwaves101 key chain pocket knife! Impress your friends, if not your boss!

New for January 2013: the mortuary has now been separated by year, as we have had a few complaints about how long it takes to load. But maybe it is time some of you considered a better broadband connection to the internet?

Here are links to our archived Mortuary pages:

2012 Mortuary

2011 Mortuary

2010 Mortuary

2009 Mortuary

2008 Mortuary

2007 Mortuary

2006 Mortuary

2005 Mortuary

2004 Mortuary

Note to mortuary contributors: please consider that your boss may not find your submission in the best interests of your Big Company. Lately we've been getting a lot of "please remove my submission" emails, try not to send us anything that you might regret.

Note to Big Companies: Don't blame us for posting your spectacular failures, we only post what your employees send us. On the other hand, please don't rip off Microwaves101 pictures for presentations without permission, that's bad manners. Maybe it's time for some training!

Note to mortuary fans: In many cases, if you click on pictures on this page you can see higher resolution images.

New for February 2014! This came from Darrell, the microwave version of taped nerd glasses. Darrell also helped us out with some new information on mitered bends in microstrip (thanks!) Click image for more detail....

.... a photo of some glasses I repaired with some semi-rigid coax in college.

New for December 2013: thanks to Walter, we have the following "good example" of an antenna installation, directly from Brazil!

 

 

New for October 2013: This image came from Robert, an academic type that likes to build things too. Thanks!

I was wandering though the lab of a colleague and came across this (attached). I could scarcely believe what I was looking at - a length of RG58 coax soldered onto an N-type male-to-male coupler to form a makeshift N-type "plug".  

Thankfully I make sure our technician keeps all of my good microwave cables and VNA cal kits locked away!

 

 

 

 

 

New for September 2013: this TO-3 disaster came from Andy:

I was using an LM338 voltage regulator in a 24V PSU to power a 100 Watt DC motor. I inadvertently swapped the leads over while it was running at full pelt.  It immediately turned into a generator and forced a huge backward current into the regulator, resulting in total destruction of the device.

The TO3 can was easy to cut open to view the carnage under a microscope

 

 

New for June 2013: This came in from Matthew:

Here I've got a GSG probe which has seen better days.  An RF FET was being tested, and I think that it had some contamination under the source airbridge which caused a drain to source short.  The FET evaporated with an audible snap.  Fearing the worst I looked into the microscope and saw this.  I think that the probe was hit with some of the shrapnel from the FET which bridged the contacts causing the melty result here before source compliance could kick in.

 

New for April 2013: These photos came from Dave:

Here is an interesting item.  From a High Power HV SMPS, that is part of an old Varian TWTA.  One of the noisy types that scream at some 4 kHz....   200W out CW, 2 to 4 GHz, one of the "old school" types.

SnubberFail-1, the overall view of the board after we removed it from the amp.   Even more spectacular when you realise that the amp was still usable in that state!   We were told that it "just made a pop" but carried on working.  The customer only took the lid off to look, after finishing some testing.

That board is the main Switching Regulator card that in turn feeds the inverter that (literally) whistles up the HV.  It's fed from raw rectified 230VAC.  (No such thing as PFC when that was built!)

What's not shown, is the mass of resistor wire that spilled out of the exploded resistor, that in turn was entangled around all sorts of stuff, while still connected to the raw DC etc.   I guess it's insulated, as there were no shorts or other explosions.   No fuses were harmed either!

I apologise for not reacting in time and getting a picture of that mess, but even so, it's remarkable this unit survived relatively unscathed, and carried on working after the "Pop" (they say...)

SnubberFail-R and -C are closeups (as much as a phone-camera will allow) showing the result in detail.

The cap is (was) a 10,000pF 500V Silvered Mica part.  What caused it to fail we don't know, that and with all the other high power RF and switching stuff we deal with, we've never seen a Mica cap fail like that before.  Or for that matter, one of the aluminium clad resistors explode...

After stripping many parts from the board, giving it a good scrape wash and brush up, refitting the removed (good) parts back in their original positions, plus a new resistor and Silvered Mica cap, normal service was restored (we went through the recommission after repair procedure, but found no issues) resulting in a happy customer to boot, who were bracing themselves for a rather large replacement amplifier bill.  Not that with the time involved for all the above, it was a low cost fix, but much lower than the replacement cost of the entire unit.

After that, they then brought us (the day they collected the Varian) an old Logimetrics Pulse RF TWTA, that wouldn't do more than about 2% duty.  (It was spec'd to at least 40%)  We found a failed resistor in a medium power stage that caused the Grid drive to fail when pulsed beyond a low%, tripping the HV as a result.   Another old but high value bit of kit saved from the skip.   What they will bring us next, who knows...

(Click on images to view close up)

New for February 2013: This photo or the spectacular 2011 television tower fire and collapse in Hoogersmilde came from Ivo:

Today I had a look at your Microwave Mortuary pages….fantastic!!

It remind me of what happened here in The Netherlands at July 15th, 2011. A local 300 meter TV-tower collapsed due to a fire in the tower.

You can find more info (sorry; in Dutch) on:
http://fmtvdx.eu/zendmast/smilde/hoogersmilde.html

 

This is a good chance for you to try out Google's translator, check it out! be sure to click the links at the bottom of the page to see a zillion high-res images of the carnage, plus videos.

Also, this is a appropriate time for us to review the story of Hans Brinker, although it is more of piece of American culture rather than Dutch, they did create an awesome and inspirational statue of the boy and the hole in the dike to remind us all of what we do every day at work- UE

 

New for February 2013: these photos came from Tom, we'll let him tell the story. But let's first point out first that Teddy bears in museums deserve more respect, especially Misiu. And the movie Ted should win Best Picture for 2012 in our opinion.

Here at our facility, visited by thousands of happy children and their families every week, we have a pool with four Tornado remote controlled boats (not the Tornado corporation that makes rigid inflatable boats for people to ride in, but the one that makes amusement park interactives!) Anyway, over the past nine years of operation, at times the Tornado boats like to prove the old adage that electricity and water do not mix.

Over time the 12 volt DC power to the motors (which are beautiful Swiss made Maxon DC brush type and survive insane high mileage) simply made the traces Go Away.

Also, you will find attached the control board from a "ClearVue" condensate pump, on which the pump's holding tank apparently overflows right into the control board the first time it has trouble keeping itself drained, a karaoke booth that got a morocca through its monitor, and what some of our guests did to a giant teddy bear.

The one of the broken ELO Touchsystems monitor is curious and haunts me to this day. I still stay up at night sometimes wondering what possessed this one fifth grader on a class trip to decide to interact with the karaoke booth menus by smashing the Surface Acoustic Wave touch sensing glass with a morocca. I even nicely asked the child after the fact but he was inconsolably crying and could not get a word out. It will be a mystery forever.

 

 

 


 
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