The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Tag: Repairs

If it used to work, it can work again

Sears / Kenmore Progressive Vacuum Cleaner: Motor FAIL

After seven years, our Sears / Kenmore Progressive vacuum cleaner gave off a horrible screech and an intense smell of electrical death, prompting me to tear it apart.

It’s easy to find the two front screws holding the top in place, although you’ll need either a bendy or offset screwdriver to remove them:

Sears Progressive Vacuum – front case screws

Pull up hard on the cord retraction plunger to remove it, revealing the two rear screws:

Sears Progressive Vacuum – rear case screws

Extract the wires and motor control PCB from their niches:

Sears Progressive Vacuum – motor assembly overview

Prying the latch in the middle of the rear panel (over on the right) releases the motor assembly, which you can then wiggle-n-jiggle upward and out:

Sears Progressive Vacuum – extracting motor assembly

Disconnect the wires, peel off various foam bits, and extract the motor from its carapace. Measure the blower diameter and cut a suitable plywood clamp for the bench vise:

Sears Progressive Vacuum – custom motor clamp

I loves me some good laser cutter action, even when the plywood crate the laser came in doesn’t have much to recommend it:

Sears Progressive Vacuum – failed plywood clamp

I vaguely recall reading the purple tinge comes from the bromine vapor used to dis-insect the wood during manufacturing, before shipping it halfway around the planet.

One area of the commutator looks like it’s in bad shape:

Sears Progressive Vacuum – as-found commutator

Clean the commutator bars in the desperate hope it’s just random crud, even though that seems unlikely, then connect a widowmaker cord to the motor terminals:

Sears Progressive Vacuum – widowmaker line cord

Use a Variac to spin the motor at a (relatively) low speed while watching the brushes and commutator:

Sears Progressive Vacuum – commutator sparking

Now, that is not a nominal outcome.

The cleaned commutator again shows signs of distress:

Sears Progressive Vacuum – scarred commutator

Indeed, measuring the resistance across the line cord terminals shows a shorted winding: 0.0 Ω with the brushes aligned on the bars just antispinward of the scars.

So the motor is definitely, irretrievably dead.

Extracting the brushes shows the arcs have eroded their spinward edges:

Sears Progressive Vacuum – eroded motor brushes

The dark smudge on the windings seems due to internal problems, rather than just the arcs, because the wiring crossing between the commutator and the smudge remains clean:

Sears Progressive Vacuum – charred motor windings

One can buy a used motor assembly on eBay for about $40, with no assurance it doesn’t also have a shorted winding.

Dang, now I gotta make more adapters for whatever vacuum comes next …

2022-12-08
Thermador In-Wall Heater

Our house dates back to 1955 and features several fancy items not found in contemporary dwellings. Take, for example, the Thermador in-wall heater in the front bathroom:

Thermador In-Wall Heater

It has a finger-friendly design apparently intended to admit a small finger through the grille, where it can easily contact the resistance heating coil, so while we were moving in I snapped a GFI circuit breaker into that slot in the breaker panel. We advised our (very young) Larval Engineer of the hazard and had no further problem; as far as I know, that breaker never tripped and no fingers were damaged.

Back then, while adding that breaker and cleaning the first half-century of fuzz out of the thing, I evidently blobbed silicone rubber on the screw terminals of the switch:

Thermador In-Wall Heater – switch contacts

They don’t make switches like that any more.

For reasons not relevant here, we’ll be using it for the first time since we moved in, so I spent a while cleaning / blowing / brushing another two decades of fuzz out of it.

Minus the fuzz, the heater no longer smells like a house on fire:

Thermador In-Wall Heater – glowing

If that doesn’t warm your buns, nothing will!

2022-11-30
Numeric Keypad Repair

Having set up a cheap wireless numeric keypad as a simple macro pad at my left hand, I eventually knocked it off the desk, whereupon the screw compressing the back of the case against the membrane switches ripped through the plastic:

Numeric Keypad – compression screw pullout

The symptoms came down to erratic operation of a few keys that became worse as I continued tapping on the thing. Finally, with nothing to lose, I took it apart and, upon seeing the hole in the case, realized I didn’t have to cut the usual label to find the hidden screw.

Slathering the little donut with acetone and clamping things together might work for a while, but I’m sure the keypad will hit the floor again with similar results.

Instead, recruit some candidates from the Box o’ Random Screws:

Numeric Keypad – screw selection

Pick the screw big enough to grip the undamaged boss on the front of the case, yet short enough to compress the back again, add a small washer spanning the hole, and it’s all good again:

Numeric Keypad – screw installed

This only works because the keypad sits at enough of an angle to hold the screw off the desk.

That was easy …

2022-11-25
Epson ET-3830 Duplexer Paper Jam

For the record, it is possible to get a piece of paper jammed so far inside the duplexer rollers in the back of an Epson ET-3830 Multifunction Printer / Scanner that it is not only completely invisible from the inside, but that it cannot be removed without disassembling the duplexer:

Epson ET-3830 duplexer jam

It jammed while attempting to print another batch of Geek Scratch Paper with a semilog grid, without actually duplexing the sheets. The specs say the printer can handle 4×6 paper, so I assumed 4.24×5.5 paper would be Close Enough. Apparently not.

Print ’em two-up, chop the sheets down the middle, pad and glue, and it’s all good:

OMTech CO2 laser power supply – bandwidth tests – semilog graph

2022-11-22
Step2 Garden Seat: Seat3

Another tray becomes a replacement for the plywood on the Step2 rolling seat in the Vassar Farms plot:

Step2 Garden Seat – weathered plywood

I reused the old hinges, as this tray seems to be slightly thicker than the one on the home garden seat. The straight edges show it’s also somewhat smaller, but it’ll work just fine.

The bottom of the tray with its Silite logo now faces upward, because the top surface has eroded to a matte finish while supporting a bunch of plants outdoors during several summers:

Step2 Garden Seat – tray top

So you can get two or three years from a painted plywood slab out in a garden, depending on how fussy you are about looks.

After two seasons, the first tray doesn’t look any the worse for wear: Silite trays really will survive the Apocalypse and be ready to serve breakfast the next day.

2022-11-21
Pixel 6a Camera Protector vs. Leaf Shredder Chaff

Much of my exercise of late has come from blowing leaves into piles and shredding them:

Leaf Shredding – GPS track

My GPS drawing hand is weak.

I wear 30 dB over-the-ear protectors with a pair of Bluetooth earbuds tucked inside for a rhythm track. I had been carrying my Pixel 6a in a side pocket, until I noticed a remarkable amount of crud inside the glass protector over the camera lens:

Pixel 6a camera protector dirt

How crud could get inside (what I thought should be) a sealed compartment inside the phone’s armor case became obvious after peeling the protector off:

Pixel 6a camera protector dirt – overview

Come to find out the protector’s adhesive layer has an opening near the edge of the camera, leaving a slot allowing the howling chaff storm onto the camera glass. Random pocket fuzz certainly contributed some particles, but the entire phone case had a surprising amount of yellow-brown dust tucked inside.

So I left the protector off, dumped the music files into my old Pixel 3a (which never had a camera protector), and will henceforth leave the 6a indoors during similar adventures.

The bagged leaves will become next year’s garden veggies, so the whole project isn’t a total waste of time.

2022-11-17
Downgrading Yubikey-Manager
It seems that Manjaro’s 5.0.0-1 version of the yubikey-manager crashes due to inscrutable errors, with the effect of not letting me use it to sign in at all the sites I’d set up to use TOTP authentication.

If the previous version (4.0.9-1) were still in the pacman cache, then downgrading would be straightforwar d:
```
sudo pacman -U /var/cache/pacman/pkg/firefox-64.0.2-1-x86_64.pkg.tar.xz
```
Regrettably, I had recently cleaned things up and flushed the cache, so I had to fetch the package (and its signature) from the “y” directory of the Arch archive, then install it:
```
sudo pacman -U /tmp/yubikey-manager-4.0.9-1-any.pkg.tar.zst

loading packages...
warning: downgrading package yubikey-manager (5.0.0-1 => 4.0.9-1)
resolving dependencies...
looking for conflicting packages...

Packages (1) yubikey-manager-4.0.9-1

Total Installed Size:   1.11 MiB
Net Upgrade Size:      -0.13 MiB

:: Proceed with installation? [Y/n] Y
<<< snippage >>>
```
Whereupon It Just Worked™ again.

I expect someone more experienced than I will have long since filed a bug report / sent a pull request / whatever, because I have little idea how to do any of that. The next upgrade should work just fine.
2022-11-10