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

Samsung Dishwasher Drying Cycle Crash: Wax Motor

Replacing the drying fan didn’t prevent the Samsung dishwasher from crashing when the drying cycle starts, so I eventually figured out how to run the “Smart Install” test sequence:

Samsung Dishwasher – DW80K7050US – p 37 – Service Test Mode

Which ticked through everything right up to the start of the “Check Drying” step:

Samsung Dishwasher – DW80K7050US – p 39 – Check Drying

Whereupon all the control panel LEDs went dark and a little red status LED on the PCB began blinking what must be an error code: long / pause / long-short-short. Of course, I cannot find any doc for that LED’s code.

The “Auto Door Open Actuator” is a wax motor, a device I had never encountered before. It opens the door through a whippletree pushing two tabs against the door:

Samsung dishwasher – door auto-open mechanism

The meter measures the voltage across the ~~wax motor~~ Auto Door Open Actuator through improvised widowmaker jumpers jammed onto the quick-disconnect fittings. As you might expect, the meter showed 000 VAC before, during, and after the crash, suggesting something is wrong with the relay intended to activate the motor.

Because the test sequence activates the drying fan after opening the door, the fan never even twitched.

For twelve bucks (spend up to $150 if you prefer), I had a generic DD66-00089A actuator in hand before dragging the dishwasher out of its lair and, being me, had to measure what it did:

Samsung Dishwasher – Door Actuator wax motor – test layout

It’s about 1.8 kΩ across the terminals and, not being fussy about its input voltage, will dissipate anywhere from 6 to 32 W in operation. Because the “motor” works by the force generated by expanding liquid wax, the response time obviously goes down as the voltage goes up.

After a few cycles to figure things out, plotting elapsed time against piston displacement is surprisingly linear right out to the 6.5-ish mm maximum stroke:

Wax Motor – time vs. displacement

It take much longer from a cold start, which is how it’s normally used, so the 30 s intercept at 0 mm is definitely on the low side.

Samsung no longer manufactures the DD82-01337A7050 control board, the usual aftermarket suppliers report it’s out of stock, and, given the lack of doc, I am loathe to pull it out of the dishwasher for failure analysis / repair. The one-hour cycle gets the dishes clean and a 46 minute countdown timer reminds me to open the door for drying, so the failure seems survivable for the immediate future.

2026-09-16
HQ Sixteen: Needle Bar Re-Reorientation
Unfortunately, orienting the HQ Sixteen’s Needle Bar to put the needle locking setscrew at the back resulted in excessive thread breakage:

HQ Sixteen – needle bar reoriented

The thread passes through the guide hole just below the hex driver in that photo, then through the hole in the needle from the front of the machine. Apparently the 45°-ish angle between those two was large enough to prevent the thread from sliding smoothly along the needle.

Proceeding much as before, but without dismantling the machine cover because I know where the clamp screw will be with the machine shaft at Bottom Dead Center …

The Ruler Foot is now 0.5 mm off the Needle Plate:

HQ Sixteen – Ruler foot clearance – 2

Stacking gauge blocks shows the Needle Bar now sits 0.355 inch above the Plate at BDC:

HQ Sixteen – gage block stack – 2

That is viewed from the right side of the machine, with the button-head screw sticking out of the Presser Bar hidden behind the Needle Bar.

The gauge block set confirming what’s in the stack:

HQ Sixteen – gage blocks used – 2

Then:
- Stick a screwdriver through the bottom access hole into the Needle Bar clamp screw
- Loosen the Needle Bar clamp screw
- Rotate the Needle Bar to put the guide hole exactly in front
- Tighten the clamp screw
- Verify the shaft is still at Bottom Dead Center
- Remove the block stack
- Install the Ruler Foot at 0.5 mm
Which looked like this with the shaft at Top Dead Center:

HQ Sixteen – needle bar reoriented – 2

There’s a quilt in progress on the left, so we’ll know if this solved the problem very shortly.
2026-09-15
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