Posts Tagged Repairs

LED Bulb in High-Vibration Environment

The garage door opener just ate another rough-duty bulb, so let’s see how a $7 LED bulb fares:

Walmart 60 W LED Bulb - garage door opener

Walmart 60 W LED Bulb – garage door opener

It has no external heatsink fins and the color temperature looks just like the old-school incandescent bulb it’s replacing, so they’re getting a clue about what’s acceptable to ordinary folks.

That’s equivalent to a 60 W incandescent bulb, too, at least according to the package:

Walmart 60 W LED Bulb - package data

Walmart 60 W LED Bulb – package data

I love the “Return the package and reciept for replacement or money back” part…



CD Ripping: Fractional Tracks

Mary gets books-on-CD at the annual library book sale, but she’s found they’re easier to use in MP3 format. We regard format transformation for our own use as covered by the First Sale Doctrine and Fair Use, but, obviously, various legal opinions differ.

I use Asunder to rip audio CDs, although it doesn’t handle non-recoverable errors very well at all. Wiping the offending disc with nose oil or ripping from a different drive will resolve most of the issues, but a recent acquisition had a nasty circumferential scratch in the middle of Track 7 that just didn’t respond to Black Magic.

CDparanoia can rip portions of a track, so a little binary search action extracts the usable data from Track 7:

cdparanoia "7-7[4:35]" Track7a.wav
cdparanoia III release 10.2 (September 11, 2008)

Ripping from sector  177155 (track  7 [0:00.00])
	  to sector  197780 (track  7 [4:35.00])

outputting to Track7a.wav

 (== PROGRESS == [                              | 197780 00 ] == :^D * ==)   


cdparanoia "7[5:30]-7" Track7b.wav
cdparanoia III release 10.2 (September 11, 2008)

Ripping from sector  201905 (track  7 [5:30.00])
	  to sector  208894 (track  7 [7:03.14])

outputting to Track7b.wav

 (== PROGRESS == [                              | 208894 00 ] == :^D * ==)   


With that in hand, you import the two WAV files into Audacity with a five second gap between them, drop two seconds of A-440 sine wave in the gap, and export to MP3.

The M3U playlist entry has the track time in seconds, so I hand-carved that entry to match the abbreviated length:

#EXTINF:376,Disc 14 Track 7
14-07 - Track 7.mp3



Hobo Datalogger vs. Hacked AA Alkaline Battery

The AA battery pack grafted onto the back of the Hobo datalogger recording groundwater temperature showed a 50% level during its most recent dump, so I swapped in a pair of new AA cells.

The pack hack dates back to 2009-09 and the Duracell Ultra cells have a “best used by” date of March 2013. Call it 5.5 years of service and, figuring an average current of 10 μA, that’s a total of 480 mA·h.

The datasheet shows many graphs at much higher currents, but a capacity of 3500 mA·h to 0.80 V at 5 mA seems pretty close. Given that they produce 2.87 V with no load, they’re still in decent shape.

However, the logger’s opinion of their voltage is what counts. To estimate that number, I checked the reports from the attic: the death planet for lithium cells.

Starting with an old Energizer failing after a few hours in December:

Attic - Insulated Box - Early battery failure

Attic – Insulated Box – Early battery failure

Two new Maxell CR2032 lithium cells also had trouble, with the first reporting a low voltage in January:

Attic - Insulated Box - Maxell battery failure

Attic – Insulated Box – Maxell battery failure

The second in February:

Attic - Insulated Box - Maxell battery low - 2015-02-25

Attic – Insulated Box – Maxell battery low – 2015-02-25

I think the Maxell cells failed from low temperature, but dead cell is dead.

That happens just above 2.85 V, so the attic datalogger now carries an AA alkaline battery pack.


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Thunderbird: Disabling an ISP Email Account

For reasons that probably make sense to them, Optimum Online (the ISP part of Cablevision) uses totally insecure password-in-the-clear user authentication to the POP3 and SMTP servers. That’s marginally OK for access through their own cable network, but, should you access those servers through a different ISP, you’ve just exposed some sensitive bits to the Internet at large.

Disabling an account in Evolution requires removing one checkmark:

Edit → Preferences → Mail Accounts tab → uncheck the account → done!

Doing the same in Thunderbird, however, requires arcane knowledge and deft surgery, documented in the usual obscure forum post containing most of the information required to pull it off:

Edit → Preferences → Advanced tab → Config Editor button

Search for server.server and find the .name entry corresponding to the ISP account. Note the digit identifying the server, which in my case was 1: server1.

Search for server1 and find the number of the mail.account.* entry with that string in the value field. In my case, that was account1.

Search for accountmanager to find the mail.accountmanager.accounts entry and remove the account you found from the Value string.


Make a note of all that information, because you must un-futz the accountmanager string to re-enable the account. Of course, if you add or remove any accounts before that, all bets are off.

There, now, wasn’t that fun?

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MTD Snowblower Muffler Bolts

One of the bolts from the replacement muffler on the MTD snowblower worked its way out of the engine block and vanished along the driveway, perhaps to be found when the snow vanishes in a few months. The muffler’s still in place, but the engine exhaust comes straight out of the port into that compartment and, because I’m running the engine a bit rich to make up for oxygenated gasoline, a beautiful blue flame jets about two inches from the bolt hole.

Being that sort of guy, I installed one of the original bolts that I’d tossed into the bin with its relatives and continued the mission.

For future reference:

  • MTD Snowthrower E6A4E
  • Tecumseh engine HMSK80
  • Tecumseh muffler 35056
  • Tecumseh bolt 651002

The bolt has, of course, delightfully custom specs: 5/16-18 x 4-3/16.

My bolt stash tops out at 4 inches, so that not-quite-1/4 inch extra length means you gotta buy an OEM bolt.

They’re $1.20 from Jack’s Small Engines, with five bucks of shipping, or you can find a kit with two bolts and the lock bracket for $12 on Amazon.

No pix, because it’s 14 °F outside and barely more than that in the garage.


Dell Inspiron E1405 vs. Ubuntu 14.04LTS vs. Broadcom Drivers

So the ancient Dell E1405 laptop on the Electronics Bench, connected to this-and-that, woke up without network connections. As in, right after booting, the link and activity lights jammed on solid, the usual eth0 device wasn’t there, WiFi was defunct, and nothing made any difference.

After a bit of searching, the best summary of what to do appears on the Ubuntu forums. The gist of the story, so I need not search quite so much the next time, goes like this:

The laptop uses the Broadcom BCM4401 Ethernet and BCM4311 WiFi chips, which require the non-free Broadcom firmware found in the linux-nonfree-firmware package. There’s a proprietary alternative in bcmwl-kernel-source that apparently works well for most Broadcom chips, but not this particular set.

Guess which driver installed itself as part of the previous update?

The key steps:

sudo apt-get purge bcmwl-kernel-source
egrep 'blacklist (b43|ssb)' /etc/modprobe.d/*
... then manually kill any files that appear ...

Apparently that problem has been tripping people for at least the last four years. That this is the 14.04 Long Term Support version evidently has little to do with anything at all.

While I was at it, I deleted all the nVidia packages that somehow installed themselves without my noticing; the laptop has Intel 945 integrated graphics hardware.

I vaguely recall what I intended to do before this happened…


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IBM L191p Monitor Stand Disassembly

Our Larval Engineer expressed a need for some monitors, so I dispatched a pair of IBM L191p panels from the heap. Despite reusing a gargantuan box from the Dell U2713HM monitor, I had to disassemble the struts from their swiveling base to fit everything inside.

The intact base has no obvious affordance to remove the covers:

L191p Monitor Stand - struts intact

L191p Monitor Stand – struts intact

After taking the bottom apart, I discovered that you just poke a screwdriver under each cover and it slides upward and off:

L191p Monitor Stand - struts cover removal

L191p Monitor Stand – struts cover removal

Duh & similar remarks.

The two covers are not interchangeable:

L191p Monitor Stand - struts cover handedness detail

L191p Monitor Stand – struts cover handedness detail

Removing two pairs of screws from each strut releases them from the base:

L191p Monitor Stand - struts disassembled

L191p Monitor Stand – struts disassembled

The projecting horns on the outboard side of those struts are exactly as delicate as you think.

I put a piece of thick cardboard sheathed in closed-cell foam between the LCD screens that separated their bezels (minus cutouts for the buttons), then taped them together face-to-face. Add foam peanuts, drop in the monitors, nestle struts beside monitors, add rigid foam blocks all around and between, put flat bases atop monitors with a foam slab protecting those strut brackets, over-stuff the box with more peanuts, forcibly tape the thing closed, and it survived the trip in good order.

A pair of 1280×1024 monitors isn’t worth insuring these days, though.