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

CUPS 2.4.19 vs. Printing
After a rather tedious morning devoted to figuring out why printing had suddenly stopped working, it seems there’s something badly wrong with the most recent CUPS update.

The symptoms included:
- Wrong sheet orientation for multi-page output regardless of the Landscape or Portrait setting
- No output at all, generally with a CUPS error message
The error messages were utterly inscrutable:
- “missing required flags”
- “cfFilterChain: pdftopdf (PID 8189) stopped with status 1”
- “temp file (object 3 0, offset 11462): dictionary has duplicated key /x12; last occurrence overrides earlier ones”
Downgrading two packages restored the status quo ante:
- libcupsfilters 2.2.1-2 → 2.1.1-4
- cups 2.4.19-1 → 2.4.16-2
Perhaps cups need not be reverted, but I’m loathe to fiddle around with it now that printing works again.

Those are now frozen in /etc/pacman.conf:
```
IgnorePkg = cups libcupsfilters
```
The least-awful way to downgrade / revert packages seems to be with manjaro-downgrade. You can, of course, do it on hard mode with pacman or pamac, but perusing a list of what’s in the update cache helped figure out what just changed.

And there they will sit until the next update rolls through.
2026-09-14
HQ Sixteen: “New” Handlebar LED FAIL

A to-do reminder pending completion of the in-process quilt strapped in Mary’s heavily customized HQ Sixteen:

HQ Sixteen – failed handlebar LEDs

A three-LED string in the central control panel of the front handlebars has gone dark a year-and-a-half after I replaced all of them. Of course, that’s what I get for using new-old-stock surplus parts, but … the COB LEDs in the nose ring lights are still going strong, so there’s plenty of light where it matters.

The star pattern on the ceiling (lower right) comes from sunlight reflecting off one of the salvaged star quilting rulers. I think the oblong patterns (upper left) come from other rulers.

2026-09-11
Prusa MK4 Camera Lighting: FAIL

Well, this didn’t take long:

Prusa MK4 – Extruder sidelight – COB LED failure

The upper five-LED string in the middle module failed open-circuit, which left the remaining two strings handling too much current. The five LEDs across the middle look like they’re running at War Emergency Power and the lower five are limping along:

COB LED failure – detail

The dark spots in the middle are overexposed pixels.

I soldered in a replacement from the same bag and it’s all good again, but I expect that won’t last very long.

2026-09-10
Huion H610Pro Tablet vs. Digimend vs. DKMS

A month or two ago the Huion H610Pro tablet’s buttons stopped working with the input-remapper macros I set up to do useful things. Considerable searching showed that the Digimend kernel driver project previously handling the buttons went inertial two years ago and, apparently, no longer worked with contemporary kernels. Further searching suggested old Huion tablets, which mine certainly is, should be handled by the native kernel / X drivers, so I uninstalled Digimend.

Which produced a persistent error message from the DKMS machinery telling me something awful was happening with the now-missing Digimend.

An Arch Linux BBS thread suggested manually removing various detritus left behind during successive kernel updates in places like /usr/lib/modules and /var/lib/dkms. Given that my desktop box runs the 6.18 kernel, I felt reasonably confident in removing the 5* kernel directories and anything mentioning digimend from those locations.

After the box started up the next morning, all the tablet buttons once again worked the way they use to.

The nice thing about Free Software is having access to all the pieces when something breaks …

2026-09-01
Nuheara IQbuds² MAX Battery Replacement: Round 3

The OEM lithium batteries in my Nuheara IQbuds² MAX not-really-hearing-aids lasted for about 2-½ years before needing replacement. Two more years pretty well did those in and I replaced them again without fanfare about a year ago.

After replacing the 802050 pouch battery in the charging case and having discovered two spare LIR1654 batteries at the back of a workbench, I installed those and renewed the gaffer tape holding the earbuds together:

Nuheara IQBudsMax2 – battery replacement

The workbench stash also disgorged the old Varta LIR1654 batteries, but not the OEM ones, so a test session seemed in order:

Lithium LIR1654

The Varta batteries (red and blue traces) are in sad shape, after two years of regular use and another three years idling in a small bag. The EEMB batteries (pink and cyan traces) are in better shape, despite their year of use, with the lower pair of traces showing their as-extracted charge and the upper three traces their just-charged capacity.

They’re still doing better than their 0.4 W·hr nominal capacity, which is not to be sniffed at, particularly as the tester’s minimum 150 mA current presents a rather stiff load for a 100-ish mA·hr cell.

This being a quick-n-dirty set of tests, a simple discharging “fixture” sufficed:

LIR1654 battery discharge clamp

The charging “fixture” wasn’t much fancier:

LIR1654 battery charge clamp

The EEMB batteries are in the bag and may remain in good shape after two more years, ready for another tour in the earbuds when their relatives wear out.

2026-08-26
Bike Helmet Mirror: Always Have A Spare

As fate would have it, the telescoping stalk on Mary’s helmet mirror broke off at the ball mount a few days after I assembled another spare mirror:

Helmet Mirror Ball Mount – broken shaft

That’s the point where all the stress concentrates, but the stalk lasted almost exactly six years and didn’t owe me anything.

So I clamped the mirror+shaft+ball from a spare into the mount on her helmet, and she rode off as planned.

Once again being down to a single spare, I drilled a few more 10 mm balls:

Helmet Mirror Ball Mount – ball drilling

Cleaning up the end of the broken shaft let me shove it into a drilled ball:

Helmet Mirror Ball Mount – repaired – drilled balls

The insert and random screw came from the stub end of the broken shaft: ramming it into the cleaned-up end makes the job look Good Enough™.

Clamp the repaired stalk into the spare mount, drop the drilled balls & lathe fixture back in their bag, and maybe it’ll be another six years before they’re needed.

Life is good!

2026-08-25
Bike Helmet Mirror: Another Spare

One of Mary’s garden neighbors recently started biking, she recommended he needed a helmet mirror, and I handed her a spare from the Bag o’ Mirrors:

Helmet Mirror Ball Mount – on helmet

So I built another one:

Helmet Mirror Ball Mount – epoxy clamping

Fortunately, the Bag also had that (slightly rusted) mirror with a drilled ball, so all I needed was a new printed mount with two brass inserts and screws.

Now we have two spares against future need:

Helmet Mirror Ball Mount – ready spares

They’re much better than the old yellow Az-El mount, but I couldn’t have made the ball mounts without that experience.

Both versions outlasted all the commercial versions we’ve had over the decades, so that’s a 3D printing success story right there.

2026-08-21