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

  • Trust Multimedia Mouse: Gummy Rubber

    While looking for something else, I found the old Trust Multimedia Mouse and discovered its nice grippy rubber surfaces had become adhesive slime. Graduated efforts with water, rubbing alcohol, and denatured alcohol being unavailing, I finally hit it with xylene and that did the trick:

    Degummed Trust Mouse
    Degummed Trust Mouse

    Of course, xylene also wiped away the fancy button markings and irretrievably scarred the surface, but at least I can pick the mouse up without having it stick to my hand. Not that I pick it up that often, obviously.

    Several other gadgets have a similar grippy finish, so now I know what to do when it turns gummy: throw the gadgets out…

  • Eyeglass Temple Spring Repair

    Another of Mary’s glasses snapped at the temple joint:

    Broken eyeglass temple spring
    Broken eyeglass temple spring

    This one has a spring inside the joint that latches the temple on either side of that square inner corner. Obviously, there’s no way to reconnect the broken stub with the spring retracted inside the brazed temple box, so:

    • File off the corner
    • Fill the socket with epoxy
    • Ease the stub in place
    • Wipe off the excess epoxy
    • Align on the workbench
    • Let it cure overnight

    At least the hinge folds again, even if the spring doesn’t work:

    Broken eyeglass temple spring - epoxied
    Broken eyeglass temple spring – epoxied

    She promises to scrap out her oldest glasses after the next eye exam…

  • Heating Blanket Controller: Soldering QC

    A friend reported that three of the four heating blankets he’s bought over the last several years have failed, so he sent the lot to me for teardown and maybe repair.

    Looking inside one controller showed some obviously bad solder joints:

    Blanket controller - bad joints
    Blanket controller – bad joints

    Hitting the joints with the soldering iron improved their outlook on life, but the controller remained dead; they weren’t really bad joints, they just looked that way.

    If the “lot number” labels on the controllers mean anything, they’ve tried three different triac mounts over the years:

    • A through-hole triac screwed to the board with no heatsink
    • An SMD triac using the PCB copper as a heatsink
    • A through-hole triac with a big aluminum heatsink

    That’s in order of ascending lot number, suggesting the triac caused some reliability problems.

    I’m still trying to figure out how to probe the circuitry without killing myself. An isolation transformer comes to mind, because the blanket dissipates only 85 W.

    Surely the triacs have snubbers…

  • Shaft Position Sensor: Trimpot Wrench

    With the shaft position sensor mounted in this position:

    Kenmore 158 Shaft position sensor - overview
    Kenmore 158 Shaft position sensor – overview

    There’s no way to get a screwdriver into the trimpot that adjusts the sensor’s trip point.

    A few minutes with tin snips, nibbling tool, and square file produced a small wrench:

    Trimpot Wrench
    Trimpot Wrench

    One side of the wrench has a 45° bend that made tweaking the pot just slightly easier.

    The proper trip point turned out to be about 90° away from where the trimpot started, with the level midway between the detection points for shiny metal tape and the cutout side of the counterweight.

  • Doorbell Switch Corrosion

    A friend, anticipating a stream of visitors for their freshly hatched baby, asked for help with a defunct remote doorbell. A bit of probing showed that shorting across the pushbutton switch contacts reliably triggered the bell, so I unsoldered it:

    Doorbell switch - intact
    Doorbell switch – intact

    A similar switch from the heap had a longer stem that was easy enough to shorten, so the repair didn’t take very long at all: ya gotta have stuff!

    An autopsy reveals the expected contact corrosion:

    Doorbell switch - parts
    Doorbell switch – parts

    Underexposing the image by about two stops retained some texture on the contact dome.

    The IC date codes suggest the box is over a decade old, which is as much life as one can expect from cheap consumer electronics, particularly with an unsealed switch placed outdoors.

    It’s probably good for another decade…

  • NYS DOT Patch Quality

    After years of neglect, an NYS DOT crew started a really nice repair job on the inside edge of the curve just north of our house. They milled out the deteriorated road surface, cleaned out the debris, and laid in a patch flush with the road surface. That’s quite unlike their usual shovel-some-cold-patch / hand-tamp / drive-over-it process, made familiar everywhere else around here.

    Unfortunately, for unknown reasons, they didn’t fill in the last two feet of the milled-out trench, leaving a tooth-shattering pair of perpendicular edges exactly where you’d least expect them:

    Rt 376 north of Heathbrook - unfinished patch
    Rt 376 north of Heathbrook – unfinished patch

    Ran out of asphalt? Lunch break? Called off to another emergency? We’ll never know.

    I sent a note, with that picture, to the NYS DOT Bicycle & Pedestrian Coordinator, asking what happened; perhaps they planned another layer atop the whole curve to seal the rest of the cracked pavement?

    The next day a crew filled in the hole, which I find far more than coincidental.

    Although it’s better than it was, there’s now a joint that will deteriorate more rapidly than the uniform asphalt layer they should have created.

    We’ll take what we get…

  • If You Can Get To BNC, You Can Get To Anything

    That’s what Mad Phil taught me, back in the day, and it’s still true:

    15 W Dummy Load - Stacked Adapters
    15 W Dummy Load – Stacked Adapters

    From the top:

    • 15 W dummy load with N female
    • N male to BNC female
    • BNC male to UHF female
    • UHF male to UHF male
    • UHF female on homebrew antenna mount

    Obviously, I don’t have enough adapters: I need one with N male to UHF male.

    I actually spent money to get from the reverse-polarity SMA connector on the Wouxun radios directly to UHF female, matching the cable to the antenna mount in one step.

    Sometimes an unsteady ziggurat of adapters isn’t appropriate.