Fail of the Week: Blown Light Bulb Controllers

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We’ve been meaning to get around to this one for many weeks now. It’s been hard to find good fail write-ups… it’s as if hackers are afraid to admit that sometimes projects fail. We hope you’ll shake off that opinion as failure is the fastest path for learning and true understanding!

[xymax] was working on a control system for a chandelier with 150 bulbs which use 5 Watts each. This project was being readied for the NYC Resistor Interactive Party which [Adam Fabio] attended last month. As deadline for the show approached, the last piece was put in place late into the night… but it was connected backwards. In a tale worthy of a slapstick movie, the reverse polarity caused a chip on all seven controller boards for this module to blow like the one seen above. But that’s not all, the laptop being used during prototyping was connected by USB and started smoking!

All of us feel the pain of this type of equipment failure. Luckily [xymax] looked for lessons to learn instead of dwelling on the mistake itself. Use protection diodes, keyed connectors, and write about your failures. Hopefully reading this will help others avoid a similar equipment-destroying mistake.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Fail of the Week: Projector LED Retrofit

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That’s a deal for a project, how hard could it be to fix it up?

If you’re a real hacker we’d wager you’ve fallen for this type of thought process before. [Luft] bought this used Sharp XR-10X-L projector about a year back and planned to retrofit it with an LED bulb. He gathered all the parts and got to work, successfully testing and installing the modifications. But as luck would have it, the project is stuck in some type of boot loop.

This fail is certainly not for lack of preparation. The first post documenting his adventure shows that the hack has been done before, he acquired the service manual for this particular hardware, and he did his homework when ordering the parts. Success requires circumventing some sensors which ensure the case and internals are in place, and making sure the electronic status of the ballast is reported correctly event though it’s not needed for the LED source. Power-on gets as far as illuminating all the indicator lights in green as it should, but is then followed closely by a reboot sequence.

He tried watching the serial port to see if he can get any status info there but no dice. In keeping with the nature of this column, let’s see if we can provide any constructive troubleshooting advice in the comments.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Fail of the Week: Rewiring Robosapien

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Our first thought was “check out all of those TO-92 components!”, but then we saw the wiring nightmare. [Tom] picked up a Robosapien from an estate sale for just $10. Most hackers couldn’t resist that opportunity, but the inexpensive acquisition led to a time-consuming repair odyssey. When something doesn’t work at all you crack it open to see what’s wrong. He was greeted with wiring whose insulation was flaking off.

This is no problem for anyone competent with a soldering iron. So [Tom] set to work clipping all the bad wire and replacing it with in-line splices. Voila, the little guy was dancing to his own tunes once again! But the success was short-lived as the next day the robot was unresponsive again. [Tom] plans to do some more work by completely replacing the wires as soon as he receives the replacement connectors he ordered. So what do you think, is this an issue that will be resolved with a wire-ectomy or might there be actual damage to the board itself?


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Fail of the Week: CPLDs That Release Blue Smoke

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The card you see above is a floppy drive emulator for Macintosh. [Steve Chamberlain] has been hand assembling these and selling them in small runs, but is troubled by about a 4% burn-out rate for the CPLD which has the red ‘X’ on it. He settled into figure out what exactly is leading to this and it’s a real head-scratcher.

He does a very good job of trouble-shooting, starting with a list of all the possible things he thinks could be causing this: defective part, bad PCB, bad uC firmware, damage during assembly, solder short, tolerance issues, over-voltage on the DB connector, or bad VHDL design. He methodically eliminates these, first by swapping out the part and observing the exact same failure (pretty much eliminates assembly, solder short, etc.), then by measuring and scoping around the card.

The fascinating read doesn’t stop with the article. Make sure you work your way through the comments thread. [Steve] thinks he’s eliminated the idea of bad microcontroller code causing damage. He considers putting in-line resistors on the DB connector but we wonder if clamping diodes wouldn’t be a better choice (at least for testing purposes)? This begs the question, why is he observing a higher voltage on those I/O lines during power-up? As always, we want to hear your constructive comments below.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Fail of the Week: Secret Agent-Style Book Hideaway

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Ah, the movies are an inspiration for so many projects. How many times have you seen a spy movie where a cutout in the pages of a book are hiding something? This was the inspiration which led [Paul] and his crew to try using a laser cutter to remove a handgun-shaped cutout from the pages. The fail began before the project even got started. The sacrificial book they had chosen was too thick to cut directly so they tore it in thirds for the cutting process.

The hijinks are portrayed well in the clip after the break. The infectious giggling as this first trace of the laser cuts the outline makes the video worth watching. As they try to go deeper, the success falls off rapidly. This makes for a great Fail of the Week discussion: Why can’t you cut through multiple layers of a book with a laser cutter? Is this merely a focal length issue that would be solved with a higher-end cutter or is there something else at play here. Let us know what you think by leaving a comment below.

 

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Fail of the Week: The Demise of Lil’ Screwy

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The subject of this Fail of the Week installment is entertaining if nothing else. [Chris] decided to see what kind of forces his home-built 100 ton press could stand up to. Turns out the press failed at punching a 1.5″ hole through 1/2″ plate steel.

If you didn’t see it back in February make sure you take a gander at the premier of Lil’ Screwy. The diminutive press packed quite a bit of punch, using four hand-cranked screws to knock out holes in metal. [Chris] decided to tie-one-on and take his lathe for a spin to machine the larger 1.5″ punch set.

He probably should have known when he switched from a 4-foot ratchet to a crescent wrench with a 12-foot pipe for leverage that this was going to be more than the press could handle. The bottom plate seen in the image above is beginning to cup, which in turn jams up the screws in the off-kilter threads.

We fell a bit guilty in admitting we love to see equipment pushed to the point of failure like this. But perhaps that’s part of what this column is all about. Our favorite is still the PCB shear failure, but this comes in at a close second. Check out the video presentation after the break; just be warned that there’s a bit of rough language as part of the narrative.

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Fail of the Week: Unconnected Nets in KiCad

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From the title and the image above you surely have already grasped this Fail of the Week. We’ve all been there. Design a board, send it to fab or etch it yourself, and come to find out you’ve missed a connection. Automatic checks in your software should prevent this, but when making small changes it’s easy to overlook running the checks again. This is exactly what [Clint] did with this board; leaving a net unconnected in the schematic, which made its way through to the board layout and into the OSHPark boards.

Okay, so fix it with jumper wire which is clearly what he did (white wire in the lower left image above). But since this is rev3 of his PCB it’s pretty upsetting that it happened. The meat and potatoes of the fail is the missing software feature that led to it. KiCad doesn’t have a pin swap tool in the board layout. Really? We use KiCad frequently and didn’t realize that the feature was missing. Needing to simplify his board layout, [Clint] went back to the schematic to swap some resistor network pins by hand. He pushed the change through the netlist and into the board layout, not realizing he had left an input gate unconnected.

A bit of searching proves that pin swapping may be coming to KiCad soon. It’s on the CERN roadmap of features they plan to add to the open source PCB layout software. We remember hearing about CERN’s plans quite a while ago, and thought we featured it but the only reference we could find is [Chris Gammell's] comment on a post from back in December. It’s worth looking at their plans, these are all features that would make KiCad a juggernaut.

EDITORIAL NOTE: We’ll soon be out of story leads for this series. If you have enjoyed reading weekly about fails please write up your own failure and send us the link. Of course any documented fails you find around the internet should also be sent our way. Thanks!


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.