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Posts Tagged Repairs

Some Things Last: 100 W Incandescent Bulb

The light switch for our attic turns on a single ceramic socket at the top of the stairs. The bulb burned out a few days ago:

Long-lasting 100 W Incandescent Bulb

Long-lasting 100 W Incandescent Bulb

To the best of my knowledge, that bulb has been in service since we moved in almost two decades ago. Most likely, it was installed when the house was built in 1955, because it matches several new-old-stock bulbs in a battered box that Came With The House™.

To be fair, the attic light doesn’t see much service, but … it’s been a great cost-performer!

The attic temperatures range from well below 0 °F in the winter to well above 120 °F in the summer, so it’s no place for CFL or LED bulbs. I swapped in a 60 W bulb from my heap, although I doubt it’ll be good for another half-century.

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Planet Bike SuperFlash Case: PUSH Fatigue

The blinky light on Mary’s bike became intermittent and, after a week or two, I figured out why:

Planet Bike Superflash - fatigued PUSH

Planet Bike Superflash – fatigued PUSH

The white plastic case has a thin section labeled PUSH over the switch. After five years of exposure to the sun (it faces upward on her bike) and upwards of 2000 pushes (5 years x 200 rides/year x 2 pushes/ride), the edges of that little plate cracked, it slipped inward, and jammed the switch button.

I swapped it for the one on my bike, which mounts with the switch downward and has seen much less use since I began running the Fly 6 rear camera + blinky light, and it was all good.

The fractured plate slid snugly back in place, a few drops of IPS 3 solvent-bonded the broken edges, and a snippet of good 3M electrical tape inside the case should provide a bit of reinforcement:

Planet Bike Superflash - reinforced cover

Planet Bike Superflash – reinforced cover

It’s now on my bike, just in case it’s needed.

That was easy …

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Amazon EK3211 Kitchen Scale

An unfortunate incident put enough water inside our kitchen scale to, ummm, render it inoperative. After a day of drying proved unavailing, I had nothing to lose by disassembling it.

The central label on the back conceals two screws holding the platform to the aluminum beam:

Amazon EK3211 Scale - platform underside

Amazon EK3211 Scale – platform underside

The metal plate twist-locks into the plastic platform. The hot-melt glue holding it in position suggests my construction techniques aren’t all that far off the mark.

The beam cantilevers from a metal structure spreading the load across the plastic base:

Amazon EK3211 Scale - interior overview

Amazon EK3211 Scale – interior overview

These are “after” pictures. Suffice it to say the interior was wet, including water droplets between the LCD panel and its plastic cover. Everything came apart easily, including the LCD with its attached zebra connector, and dried out thoroughly over the next day; I parked the panel atop my monitor for some gentle heating.

After reassembly, it still didn’t work, which turned out to be due to both wires from the battery snapping off at their PCB solder joints. I didn’t think I’d handled it that roughly, but ya never know.

With the wires soldered in place, the scale lit right up again:

Amazon EK3211 Scale - display PCB switches

Amazon EK3211 Scale – display PCB switches

The display flashed CAL at one point during the proceedings, although the rather thin manual had nothing to say about recalibration and the PCB didn’t have any obvious test points / jumpers / labels to that effect.

Two days of relentless spelunking produced my test weights:

Amazon EK3211 Scale - test weights

Amazon EK3211 Scale – test weights

Given the provenance of those weights, a 0.2% error might not be the scale’s fault, even if it cost barely 10 bucks.

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Bosch Laser Rangefinder Corrosion

A few days after using my Bosch GLR225 Laser Rangefinder, it wouldn’t light up.

This came as no surprise:

 

Bosch GLR225 battery contact - corrosion

Bosch GLR225 battery contact – corrosion

Some vinegar, a bit of scrubbing, some rinsing, and it’s all good:

Bosch GLR225 battery contact - cleaned

Bosch GLR225 battery contact – cleaned

The OEM batteries seem to have survived nigh onto four years, so I guess I can’t complain.

Mutter & similar remarks.

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Kensington Expert Mouse Cable Replacement

My posts about troubles with the Kensington Expert Mouse scroll ring remain disturbingly popular. My most recent warranty replacement has been running fine for several years, so I suspect they had a bad lot of IR detectors go their production line and into the field.

In any event, a recent email asked about where to get the little connector inside the mouse to replace a worn-out USB cable:

Kensington Expert Mouse - internal USB connector

Kensington Expert Mouse – internal USB connector

Maybe you’d be lucky enough to find an identical connector inside an old mouse in a junk box, but that’s not the way to bet.

Given that you need not only the proper plastic shell, but also the pins and the crimper for a proper repair, I suggested just chopping the wires an inch from the connector and splicing the new cable onto the wires.

Not an elegant solution, but it works for me …

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Monthly Science: Sonicare Recharge Intervals

After replacing the NiMH cells in my Sonicare toothbrush in July 2012, they delivered about 21 days = 21 brushings between charges. After a year, I laid a sheet of Geek Scratch Paper on the windowsill (*) and noted pretty nearly every recharge:

Sonicare recharge - 2013-10 - 2017-01

Sonicare recharge – 2013-10 – 2017-01

Anyhow, the original cells crapped out after 2-½ years, when these still delivered 13 days. After 4-½ years, they’re lasting 12 days between charges.

Color me surprised, because they’re 600 mA·h NiMH cells. The originals were 2000 mA·h cells, which you’d expect would last longer, but noooo.

No reason to change them yet, which is good news.

FWIW, I recently bought some cheap brush heads from the usual low-end eBay seller. The OEM brushes have colored bristles which fade to tell you when to change brushes, although I run ’em quite a bit longer than that. The cheap replacements have never-fading colored bristles and, I suspect, all the bristles are much too stiff. The dental hygienist says I’m doing great, so it’s all good.

Sonicare brush heads - cheap vs OEM

Sonicare brush heads – cheap vs OEM

High truth: at best, you get what you pay for.

(*) Being that type of guy has some advantages, if you’re that guy. Otherwise, it’s a nasty character flaw.

 

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Raspberry Pi Slowdown

At first, the yard camera worked fine, but a few days later the stream of JPEG images would unpredictably stall. I connect to it through a public-key SSH session and, sometimes, the login would stall for tens of seconds and, with a session set up, various exciting operation like, say, htop would unpredictably stall; if I waited long enough, they’d complete normally.

This seemed familiar:

Samsung 16 GB Evo MicroSD card

Samsung 16 GB Evo MicroSD card

It’s a known-good card from a reputable supplier, not that that means much these days. The camera flash highlights the gritty silkscreen (?) texture of the orange overlay, but the production value seems high enough to pass muster.

Popping the card in my desktop PC showed:

  • It remains functional, at least to the extent of being mount-able and write-able
  • 3probe --time-ops /dev/sdb showed it still held 16 GB
  • fsck -fv /dev/sdb[12] shows no problems
  • Both partitions looked good

So I shrank the main partition to 7.5 GB, copied the image to the desktop PC’s SSD, fired up the Token Windows Laptop, ran the Official SD Card Formatter, and discovered that it thought the card had only 63 MB (yes, MB) available. That’s the size of the FAT boot partition, so I returned the card to the desktop PC, unleashed gparted on it, blew away the partitions, reformatted the whole thing to one 16 GB FAT32 partition, and stuck it back in the laptop, whereupon the Official Formatter agreed it had every byte it should.

A format-with-overwrite then proceeded apace; the card doesn’t support format-with-erase.

Back in the desktop, I copied the saved image back onto the card which, en passant, blew away the just-created FAT format and restored the Raspbian partition structure. The 8 GB of that copy proceeded at an average 12.1 MB/s. I did not watch the transfer closely enough to notice any protracted delays.

Back in the Pi, the card booted and ran perfectly, sending an image every second to the laptop (now running its usual Mint Linux) on the guest network:

Turkey flock in driveway - 2017-03-21

Turkey flock in driveway – 2017-03-21

SSH sessions now work perfectly, too, and commands no longer jam.

So it seems a good-quality MicroSD card can experience protracted delays while writing data, to the extent of tens of seconds, stalling the Pi in mid-operation without producing data errors or any other symptoms.

It’s not clear the Official Formatter does anything that simply copying the image back to the card wouldn’t also accomplish, although overwriting the entire 16 GB extent of the card exercises all the cells and forces the card controller to re/de/un/allocate bad blocks. If, indeed, the blocks are bad, rather than just achingly slow.

Moral of the story: Don’t use MicroSD cards as mass storage devices, at least not for industrial applications that require consistent performance.

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