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

Nuheara IQbuds² MAX Battery Replacement
Nuheara predicts two to three years of battery lifetime for their IQbuds² MAX not-really-hearing-aids and, indeed, after 2-½ years of more-or-less steady use, the right bud developed a bad case of not charging fully and discharging quickly. The batteries are not, of course, customer-replaceable, so one can:
- Buy a single bud
- Buy a complete new pair + case + accessories
- Ask about their repair service
Unsurprisingly, a single bud costs more than half the cost of the full set and the repair service is a complete mystery. Given that the left bud’s battery will likely fail in short order, let’s find out what’s inside.

Your ear sees this side:

Nuheara IQbud – bottom view

The dark oval is a (probably IR) sensor telling the bud when it’s jammed in your ear.

Everybody else sees this side:

Nuheara IQbud – top view

The small slit over on the right and the two holes around the top seem to be for various microphones.

Jamming a plastic razor blade into the junction between the two parts of the case, just under the mic slit, and gently prying around the perimeter eventually forces the adhesive apart:

Nuheara IQbud – case splitting

Do not attempt to yank the two pieces apart, because a ribbon cable joins the lower and upper PCBs:

Nuheara IQbud – ribbon cable

The metallic disk in the lower part is the lithium battery.

Ease the upper part away, being very careful about not tugging on the ribbon cable:

Nuheara IQbud – raising battery

The battery has moved upward, revealing the lower PCB.

Rolling the upper part toward the ribbon cable eventually produces enough space to extract the battery:

Nuheara IQbud – battery freed

Note the orientation:
- The rebated end is the negative terminal and faces outward
- The wider end is the positive terminal and faces inward
With the battery out, you can admire the PCBs and ribbon cable:

Nuheara IQbud – interior view

What is not obvious from the picture: two pairs of spring-loaded pogo pins contacting the battery. There is no actual battery holder, as it’s just tucked into the structure of the bud, with the perimeter adhesive providing the restraining force for the pogo pins.

The battery seems a variant of a standard 1654-size lithium cell:

Nuheara IQbud – OEM ZJ1654A lithium cell

The 1654 cells I got came with wire leads welded to the cell and a complete Kapton enclosure; apparently other devices use soldered connections rather than pins. They proudly proclaim their “Varta” heritage, but I have no way to prove they actually came from Germany.

I snipped off the wires, carved a pair of holes through their Kapton for the contact pins, tucked the cell in the bud, pressed the halves together, applied a clamp, then wrapped a strip of Kapton tape around the perimeter:

Nuheara IQbud – reassembled

It seems remarkably easy to wrap the tape over the front microphone, but don’t do that. Conversely, sealing the entire perimeter is the only way to prevent acoustic feedback, so I added a snippet of tape just under the front mic opening.

Do that for the other bud and declare victory.

That is, fer shure, not the most stylin’ repair you’ve ever seen, but I was (for what should be obvious reasons) reluctant to glue the halves together. I expect the tape to peel off / lose traction after a while, but I have plenty of tape at the ready. Worst case, I can glop some adhesive in there and hope for the best.

Because the buds lost power during their adventure, they required a trip through their charging case to wake them up again. After that, they work as well as they did before, with consistently longer run time from both buds.

Whew!
2023-10-10
Moonlander Keyboard vs. Board Chow

The Moonlander keyboard has per-key LEDs that I’ve denatured enough that most show a pale gray, with a few others highlighted in orange. A few weeks ago the LEDs on the right-hand thumb cluster and the N key went nuts, cycling through a surprising assortment before settling on bright red; the obvious resets / firmware reflashing / tapping were all unavailing.

ZSA’s tech support recommended taking the thumb cluster apart to check the ribbon cable connecting it to the main keyboard half:

Moonlander thumb cluster – PCB bottom

Come to find out my unclean personal habits lodged a particularly corrosive nugget of board chow on the cable:

Moonlander – corroded ribbon cable

It’s a more-or-less standard 0.5 mm pitch cable, but only 20-ish mm long, much shorter than the cables carried by the usual sources. ZSA sells them for $2 each, plus $25 courier shipping, so I bought three; they arrived in two days from halfway around the planet.

Because I don’t foresee my personal habits changing any time soon, I tucked a Kapton tape snippet in the gap to serve as a gutter:

Moonlander thumb cluster – tape shield installation

That’s with the two hinge screws out and the cluster eased down-and-away from the keyboard enough to get the tape pressed against the keyboard.

With the screws installed and the cluster at its normal most-downward angle, the gutter closes up:

Moonlander thumb cluster – tape shield folded

With the cluster in its normal operating position (for me, anyway), the gutter is nearly invisible:

Moonlander thumb cluster – normal position

For the record, I tucked the remaining ribbon cables inside the left-hand thumb cluster against future need.

2023-10-09
Tour Easy: Another SRAM Grip Shift Indicator

After about five and a half years, the OEM shift indicator in my rear SRAM Grip Shift failed, so I replaced it with a piece of right-angle polypropylene backed with hot pink vinyl:

All done by hand, because it’s easy.

I’d used up my stock of genuine replacement indicators long ago, but they’re now down to two bucks (probably because Grip Shifters are obsolete) and I’ve stocked up in anticipation of future need.

Let’s see how long this one lasts …

2023-10-02
Cheap Rechargeable Kitchen Scale: FAIL

While pondering what to do with the shattered kitchen scale, I got a bottom-dollar replacement touting its rechargeable lithium battery. After giving it the obligatory charge-before-using, I put it in service. Five days later, its battery was dead flat discharged.

So I gutted it to extract the battery:

Cheap digital scale – lithium cell

It’s a cute little thing, isn’t it?

Much to my surprise, the obligatory battery rundown test showed it matches its 0.74 W·hr label:

Kitchen Scale – Charge1

We all know where this is going, right?

Crunche a connector on the battery, another on the scale, and make up a suitable current tap for a meter:

Cheap digital scale – current measurement setup

Which looked like this:

Cheap digital scale – active current

That’s about what I found for the craptastic scale running from a pair of CR2032 primary cells, so it’s not out of line.

Turn off the scale and measure the idle current:

Cheap digital scale – inactive current

Do you think I got a dud?

For all I know, the little microcontroller under the epoxy blob is running a continuous attack on my WiFi network, with the intent of siphoning off all my sensitive bits. Ya never know.

Dividing the battery’s 200 mA·hr rating by 4 mA says it really should be dead in 50 hours, which is close enough to five days: diagnosis confirmed!

Rather than fight, I switched to a battery with more capacity:

Cheap digital scale – NP-BX1 replacement

It’s long past its prime, but ought to last for a month, which is about as long as the shattered scale survived on a similar battery.

Sheesh & similar remarks.

2023-09-27
Tour Easy: Rewheeling

After 22 years and well over 30 k miles, I finally replaced the rear wheel rim on my Tour Easy, which went as smoothly as one could want.

The tire showed considerable wear and damage, with this gash dating back three years:

Schwalbe Marathon Plus – W5W gash

The pebble caught in this crater has worn flat on the outside and started cutting through the tire carcass into the tube:

Schwalbe Marathon Plus – Stone gash

Gotta love those Marathon Plus tires!

So my bike now has a new tire, tube, and rim on the back.

The old spokes looked OK and tightened up without incident. For the record, the Park TM-1 tension meter puts the drive-side spokes at 25 and the other side just under 20, with the total runout & wobble under a millimeter.

Having now replaced all four rims on our bikes over the course of two years, I sawed the three rims still awaiting recycling into samples:

Tour Easy – 30 k mile rim wear

Unlike contemporary bikes, our Tour Easy recumbents have rim brakes and those original rims are pretty well worn out; they’re not supposed to be concave like that.

All in all, more Quality Shop Time™.

2023-09-21
Solar-Flattening Fiskars Cutting Mats

Fiskars cutting mats must lie flat on the table to be of any use, but they’re remarkably sensitive to warping due to localized temperature variations; a hot cup of tea can wreak a remarkable amount of damage. Suggestions from the InterWebs generally involve a clothes iron, temperature tweaks, overnight cooling, and unpredictable results.

Given that the mats are large polypropylene sheets, I figured applying moderate heat to the entire mat while it’s compressed between two flat plates would work better:

Fiskars cutting mat – solar flattening

That’s one of Mary’s 36×24 mats atop an MDF sheet (with pictures of wood laminated to both sides), under a 7/32 inch = 5.6 mm sheet of non-tempered glass, with a maple shelf supporting the last two inches of the unwarped edge, all sitting on the driveway in full sun.

The first attempt started too late in the afternoon for good heating and, after a few hours, had only slightly reduced the warp. Laying it out the next morning got the mat up to about 110 °F = 43 °C around noon and the warp was completely gone by evening.

I don’t trust the IR thermometer’s temperature measurements on glass, but the surrounding MDF and driveway were plenty hot.

The next sunny day flattened the warp out of 24×18 inch mat on my desk, so success wasn’t a fluke.

We noticed that the larger mat is now uniformly smaller by about 3/16 inch along the 36 inch width and 1/4 inch over the 24 inch height. It was a tag sale find with unknown provenance and, due to the warp, Mary had been using her other large mat for layout, so we don’t know if this one arrived a little short or if my technique both flattened and shrank it.

The smaller mat seems unaffected by its similar treatment, so your mileage may vary.

In any event, a flat mat is much more useful than a warped mat, so we’ll call the operation a success.

2023-09-19
Craptastic Kitchen Scale: Shattered

So it turns out the surface of the craptastic kitchen scale really was tempered glass:

Kitchen scale – shattered glass

That’s after an inadvertent drop edgewise onto the concrete patio.

Stipulated: given what I’ve already done to / for the thing, the usual warranties do not apply.

The frame around the NP-BX1 lithium batteries held the glass fragments together surprisingly well:

Kitchen scale – shattered glass – detail

Of course, harvesting the good stuff resulted in a pile of fragments, but the carcass cleaned up nicely and, after grafting a temporary top made from scrap acrylic it still worked:

Kitchen scale – temporary surface

I expected to just cut a slab of 6 mm acrylic to match the original 5 mm glass, but for reasons probably related to dielectric constants, the touch controls do not work through that much acrylic. In fact, they don’t work through anything other than the 1.5 mm acrylic shown above, which seems a bit too flimsy for normal use.

The original glass had a design screened on the back surface and covered with paint, which I can certainly mimic, but right now I’m unsure how much effort to put into the thing.

2023-09-14