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

Windows 11 for the Linux Guy: Hardware
Contrary to what I thought a while ago, the least awful way to continue running LightBurn after Linux support goes away is to stand up a dedicated Windows 11 box:

BeeLink Win 11 PC – overview

Lest it become lost in the clutter:

BeeLink Win 11 PC – detail

It’s a BeeLink Mini S12 (whatever that means) and squats near the low end of PC performance these days. I chose it based on reports from folks at Squidwrench having used similar units for various purposes without much pain, plus motivation from one of those weird Amazon “coupons” knocking the price down; it now sells for about that same price without the coupon.

It’s advertised as coming with Windows 11, but my advisors recommended a clean installation to get rid of crapware and possible pre-installed malware. I decided to start with the as-delivered system, then use the same product key to blow away the default installation.

The box / packaging did not include a Microsoft Windows Product Key and going through the first boot setup process produced this disconcerting result:

Win 11 license key – not found

More disconcerting: Windows Defender (Microsoft’s antivirus scanner / system integrity checker) was inactive and could not be installed from the MS “Store”. While not conclusive proof of pre-installed malware, the situation certainly seemed suspicious.

The seller sent a key that seemed to be for Windows 10:

BeeLink MS Product Key – Win 10 – redacted

Having been assured this would also validate a Win 11 installation, I did a clean installation using a USB flash drive produced by the MS installer, was never asked for a key, and eventually got to this point:

Win 11 Pro Installed Key – requires Digital License – redacted

Despite the missing OEM key and the footnote, everything seems just ducky:

Win 11 Activation with Digital License

I assume a clean installation blows away any malware resident on the “hard drive” (an M.2 solid state drive, of course), including rootkits and boot sector malware. My threat model does not include malware in the BIOS / UEFI firmware, which may be overoptimistic.

I declined all the optional MS products, refused various MS subscriptions, and generally tried to kill off a myriad invasive / advertising / “customized for you” features along the way. A casual search will produce many helpful guides for that process; I expect the details will change as MS continues to extract information from us. I set up a non-Administrator account for myself specifically to run LightBurn.

With that accomplished, I gave it a static IP address, created network shares to various directories on the “file server” (an ancient off-lease Dell Optiplex) holding the files I previously used with Linux LightBurn, installed Window LightBurn, got its preferences sorted out / restored from backup, and things eventually worked pretty much as intended.

Not shown in the picture:
- A trackball set up for my left hand
- A 75% keyboard
- The USB camera in the laser’s lid for LightBurn’s use.
This setup is intended for layout tweaking and laser control, not for protracted design work while standing in what’s now a 57 °F = 14 °C basement.

For what it’s worth, I must run the laser’s water chiller for half an hour to raise the cooling water to the normal 20 °C operating range; it has a water-cooled pump serving as a little heater.

The next step involved enabling Remote Desktop Protocol access so I can access the Windows box from my Comfy Chair at my usual battle station upstairs. More on that tomorrow …
2024-12-09
Handi-Quilter HQ Sixteen: Handlebar LED Replacement

One string of three white LEDs in the left handlebar of Mary’s Handi-Quilter HQ Sixteen died over the past two decades:

HQ Sixteen – left LED deaders

A view minus the glare:

HQ Sixteen – left LED PCB

I replaced all 15 LEDs with new-old-stock white LEDs from my stash, while neglecting to pay close attention to the silkscreened orientation marks.

I used up a lot of solder wick while re-extracting seven of the LEDs :

HQ Sixteen – left LED PCB – orientation

The LED in the front-right corner is in the string with the two LEDs just above it, while pointing in the opposite direction. This definitely violates the Principle of Least Surprise.

Being of sound mind, I tested all the replacement LEDs before installing them:

HQ Sixteen – LED testing

Which tedious process weeded out a couple of deaders, one with its case on backwards, and a handful of completely different white LEDs evidently from a different manufacturing batch. Buying low-budget LEDs directly from a sketchy source halfway around the planet does have its downsides.

Being that type of guy, I also tested the removed LEDs. Weirdly, one of the strings had two dead LEDs, which suggests one failed short and the increased current took another LED down with it.

Two of the three strings in the central PCB had died and were replaced without incident: they all pointed in the same direction and I can deal with consistency.

2024-12-03
White LED QC Escape

Judging from the dates codes on the ICs inside, Mary’s HandiQuilter Sixteen long-arm machine is about two decades old and many of the white LEDs in the front handlebars have gone dark:

HQ Sixteen – dead handlebar LEDs

The vertiginous view looks upward into the handlebar at the top of the machine (more on this later). The PCBs run strings of three series LEDs from a 16 VDC supply with a 390 Ω ballast resistor (oddly enough, on the ground end of the string), so one failed LED takes down all three.

I decided to replace all the LEDs, on the principle they’re surely dimmer than they used to be and to take advantage of a decade or so of improvement in white LEDs (yes, I have old stock).

After discovering that the HandiQuilter engineers violated the Principle of Least Surprise by orienting adjacent LED strings in opposite directions, I found one of the strings still didn’t light up.

Pop quiz: which one of these LEDs caused the problem?

5 mm LEDs – swapped polarity

To the best of my knowledge, all 5 mm round LED packages mark the cathode lead with a flat edge. It’s easy to remember, as the cathode side of the schematic symbol has a bar: straight bar = straight edge.

Inside, the LED chip’s cathode lead is bonded to the reflective cup, with the anode lead wire-bonded to the top.

Took me a while to see what was wrong, too.

For whatever it’s worth, the backward LED works fine.

2024-11-28
Sears Microwave: Laying-On of Hands Repair

Although essentially all kitchens feature a microwave over the stove, essentially all women have difficulty reaching it. As a result, our kitchen has two microwaves: the built-in Samsung over the stove and our trusty Sears Kenmore on the counter.

We’ve had it for a while:

Sears Microwave – data plate

Apart from the turntable rollers, it’s been utterly reliable for the last two decades, until the Start button stopped working:

Sears Microwave – control panel

The membrane switch panel seems to be in good shape, with no cracks in the plastic surface. Only the Start button failed, which suggested the switch contact pad had failed and ruled out broken matrix traces on the flexible circuitry.

Back in the day, they kept casual tinkerers out of the dangerous interior:

Sears Microwave – Torx security screw

That would not be me:

Sears Microwave – security bit set

Over the course of two decades, an occasional food explosion produces a surprising amount of debris:

Sears Microwave – exhaust vent spatter

Go ahead, I dare you, show us your microwave exhaust vent.

The control panel circuit board & wiring looks like this:

Sears Microwave – control board – in place

Unplugging all the connectors proceeds as you’d expect, whereupon a single screw (out of sight to the top) releases the control assembly and pulling the whole thing upward gets it out of the cabinet:

Sears Microwave – control board

The capacitors show no signs of The Plague, but those resistors near the optoisolator (?) in the middle have a suspicious thermal plume.

The ribbon cable from the control surface goes into a connector with the usual locking collar:

Sears Microwave – control panel cable connector

The cable also has cutouts latching into tabs molded into the collar:

Sears Microwave – control panel ribbon cable – locking tabs

Removing two screws at the transformer releases the PCB:

Sears Microwave – control panel interior

Which promptly slammed the whole repair mission to a dead stop: with the entire membrane switch assembly glued to the front of the plastic shell, there is no way to get to the Start switch. Trying to peel the membrane off will most certainly destroy it.

Because all the other functions still worked, including the Add Minute button, we figured we can eke out a few more years before something else fails or the lack of one button gets intolerably annoying.

I reassembled everything in reverse order, plugged it in, and, while setting the clock, discovered the Start button once again worked perfectly.

It’s a classic laying-on of hands repair: take something apart, replace nothing, reassemble, and it works!

If the Start button is not part of the overall switch matrix, with a separate conductor through the ribbon cable, un- and re- plugging would be enough to restore a flaky contact. We’ll never know the rest of the story, although with this post as a reminder, maybe I can remember to tear the matrix apart when we scrap it out.

Somebody give me an Amen!

2024-11-25
Sonicare E5000 Toothbrush + Norelco T770 Beard Trimmer: Final Final Batteries

Although replacing the Sonicare E5000 battery six years ago was supposed to be the last time I’d do that, the poor thing died leaving most of a year’s supply of brush heads in the drawer.

Half a quartet of NiMH AA cells should keep it happy while using up that stash:

Sonicare Toothbrush – NiMH AA cells installed

The AA cells sit at a jaunty angle due to re-re-using the original contact tabs soldered into the PCB.

I’m getting pretty good at taping the case closed:

Sonicare Toothbrush – Kapton tape

Although I have no pictures to prove it, the other half of the AA cell quartet restored youthful vigor to the Norelco T770 beard trimmer. Having interior pictures made finding and popping its case latches so much easier.

If only I could change my batteries that easily …

2024-11-22
Sears Humidifier: Bottle Patching

Although the Sears humidifier (Model 758.154200 if you’re keeping score) that Came With The House™ works fine with its lid hinges broken, Mary heard an odd hissing sound somewhere inside. The sound continued with the thing unplugged and, after a protracted struggle in the kitchen sink, we tracked the sound to a crack in one of the dimples joining the front and back faces of the right-side water bottle:

Sears Humidifier bottle – overview

The vertical shaded bars come from the camera’s electronic shutter vs. unfiltered 60 Hz AC powering the shop LED lights.

Unsurprisingly, replacement bottles are no longer available, although you can get fill caps and valves, plus wicking filters.

A water drop squeezed in the crack:

Sears Humidifier bottle – crack

The bottles are polyethylene that sneers at any normal sealant, but I have a few square inches of tape intended for repairs exposed to weather. I didn’t get the snippet aligned just as I wanted, but its gooey adhesive definitely covered the crack:

Sears Humidifier bottle – patched

The bottles normally operate with a slight vacuum, thus the air hissing through the crack, so the tape need not withstand any continuous pressure and the adhesive layer should flow into the crack if it goes anywhere at all.

Protip: the gooey adhesive bonds instantly and irrevocably to whatever it touches, so do a trial fit before you peel off the backing tape.

If the “Serial” is a date code, it’s been around for while:

Sears Humidifier – data plate

It should be good for a few more decades …

2024-11-06
Humidifier Lid Hinges
The humidifier that Came With The House™ had a lid with two broken plastic hinges that I figured I could never replace, but while cleaning out the fuzz for the upcoming season I found one missing piece stuck inside the lid. Given a hint, I glued it back in place:

Humidifier Hinge – outlined

There’s a strip of duct tape around the outside holding the fragment in place while the adhesive cured.

A manual curve fit to the image in Inkscape produced the red outline, which gets saved as a plain SVG and fed into OpenSCAD to create a solid model:

Humidifier Hinge – solid model

The cylinder doesn’t exactly fit the end of the hinge, but it’s close enough. The straightforward OpenSCAD code making that happen:
```
// Humidfier Hinge Replacement
// Ed Nisley KE4ZNU
// 2024-10-20

HingeThick = 10.0;
PinLength = 10.0;

ScrewOD = 2.0;

NumSides = 2*3*4;
Protrusion = 0.1;

difference() {
    union() {
        translate([0,0,HingeThick])
            cylinder(d=6.0,h=PinLength,$fn=NumSides);

        linear_extrude(height=10.0,convexity=5)
            translate([-3.1,-8.0])
                import("Humidifier Hinge - ouline.svg");
    }

    cylinder(d=ScrewOD,h=4*(HingeThick + PinLength),center=true,$fn=8);
}
```
The pin has a hole for a M2 screw, but contemplation of the broken pieces suggested the pin wasn’t the weakest link, which later experience confirmed.

Figuring I’d need only one hinge, I made a spare for fitting:

Humidifier hinge – on platform

The unmodified part fit just about perfectly, whereupon a completely ad-hoc fixture involving a pair of laser-cut MDF slabs, a craft stick epoxy mixer, and more duct tape held it in place while the adhesive cured:

Humidifier hinge – fixturing

The hinge pin turned out to be half a millimeter too long, which is easily fixed, and it worked fine:

Humidifier hinge – installed

That’s more duct tape wrapped around the perimeter to hold the pieces in place, should it break again.

Which, I regret to report, occurred on the way up the stairs from the Basement Shop™ when the lid slipped from my grasp, fell away from the rest of the humidifer’s top panel, and jammed open:

Humidifier hinge – break

The PETG-CF part held together, the adhesive remained bonded to both pieces, but the original plastic fractured just below the joint. A closer look from the other side shows the break:

Humidifier hinge – break detail

The other hinge broke about where it did before.

So the humidifier remains in service with the lid in status quo ante and a small bag inside holding the fragments for the next return to the shop.

Drat!
2024-10-28