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

Subaru Forester Gas Tank Capacity, Experimental Measurement Thereof
According to the manual, which I have hitherto had no reason to doubt, our non-turbo 2015 Subaru Forester has a 15.9 gallon fuel tank:

Subaru Forester – Fuel Capacity Chart

One screen shown on the dashboard’s Multi-Function Display gives the current mileage and estimated range:

Forester – MPG Range

Dividing those two numbers gives you 13.97 gallons, the current fuel level. As you’d expect, should the average miles per gallon change, the range will change accordingly.

The trip odometer says we have driven 72.8 miles since I filled the tank. Dividing that by the average mpg gives 2.3 gallons, so the tank could possibly hold 16.2 gallons, which, given all the averages involved, is reasonably close to the 15.9 gallons shown in the manual.

Being that type of guy, I have a spreadsheet tallying each fillup since the car was new:
- 8.1 gal average
- 7.5 gal median
- 13.9 gal maximum
Long ago, my father taught me to fill the tank when the needle got halfway down and I’ve been doing so ever since. As a result, we have only rarely seen the Low Fuel Warning Light:

Subaru Forester – Low Fuel Warning Light info

A concatenation of unavoidable events put us southbound on I-87 when that light went on. Given the estimated range of 70-ish miles, I planned to refuel at the New Baltimore Service Area, about a dozen miles ahead.

The engine shut down and all the dashboard warning lights lit up with the Service Area Ahead sign in view:

Out of Gas – Service Area Ahead

All the “facilities” are blank because they’re rebuilding the whole place, with the gas station remaining open.

So I slapped the shifter into neutral and we drifted slowly along the shoulder, under the bridge visible ahead, and eventually came to a halt at the beginning of the exit lane.

There was only one thing to do:

Out of Gas – Walking On

Some storytelling later:

Out of Gas – Walking Back

Just because I could:

Refueling – GPS Track

For what are, I trust, understandable reasons, I started the tracker after I began hiking and forgot to turn it off before driving away.

After figuring out the devilishly complex spring-loaded anti-spill spout on the gas can, we drove 1500 feet to the Service Area:

Out of Gas – Service Station

As usual, I filled the tank until the nozzle automatically shut off, for a total of 13.554 gallons in two transactions:

Pump Receipts

Now, it is possible the Forester fuel system has another 2.3 gallons tucked away somewhere, but if that reserve doesn’t make the wheels go around, it’s not doing me the least bit of good.

The fact that I’ve occasionally added just short of 14 gallons suggests the estimated remaining capacity depends strongly on the average mileage up to that point and I have come very very close to running out of gas on several occasions.

As far as I can tell, the usable fuel capacity is a scant 14 gallons and the Low Fuel Light goes on with, at most, a dozen more miles in the tank.

This is the second time in more than half a century of driving I’ve run out of gas.

My father was right and I shall henceforth mend my wayward behavior.
2023-04-17
SJCAM M50 Trail Camera: Dead Remote

The remote control included with the SJCAM M50 trail camera did absolutely nothing. Not only did it not turn on the camera’s WiFi, the two indicator LEDs between the buttons didn’t blink:

SJCAM M50 remote – front view

With not much to lose, I removed those four screws and popped the back cover:

SJCAM M50 remote – interior

Yup, the OEM no-name CR2032 lithium cell was dead flat discharged. A new one perked it right up, with blinky LEDs and all.

Now I can check the camera for interesting pix without hauling it into the house:

The Early Raccoon

Plenty of critters making the rounds out there …

2023-04-11
Car USB Charger: Structural Solder Failure

The USB charger plugged into the jack formerly known as a “cigarette lighter” and now called a “power supply socket” in the car woke up dead, with a blank LED display previously showing the battery voltage / USB current / ambient temperature. Cracking the case revealed two small circuit boards:

Car USB charger – innards

You can see where this is going, right?

A closer look at the base of the side contacts:

Car USB charger – broken solder

The central tab goes through the PCB and should have been soldered on the other side, leaving the springy arms free to flex. Instead, only the arm over the topside pad had any solder; the other arm just got a solder blob atop the silkscreen over those traces.

I soldered the bottom tab, although I also resoldered the side pad. After all, the structural solder survived for quite a few years, so it might well outlive the car this time.

2023-04-07
Canon LiDE 120 Scanner vs. Sane vs. Networking: FAIL
The Canon LiDE 120 scanner on Mary’s desk gets considerable use by both of us, until a recent update of something killed network access to it. The usual searches revealed comments suggesting the sane scanner program has deliberately disabled network access to USB scanners which use the net back end, apparently to prevent loops when one instance shares a networked USB scanner already shared by another instance.

I have no clue how all that works, nor why the change has apparently taken half a dozen years to reach our scanner.

The workaround required downgrading sane on the “server” PC (the one with the Canon scanner) to the most recent version that doesn’t enforce the prohibition:
```
sudo pacman -U /var/cache/pacman/pkg/sane-1.1.1-2-x86_64.pkg.tar.zst
```
And preventing further upgrades with a stanza in /etc/pacman.conf:
```
IgnorePkg = sane
```
The pamac GUI interface now shows sane as eligible for an upgrade, then reports that it won’t do the deed. That’s survivable.

At some point, not updating the sane package will cause other problems. Perhaps by then we’ll have moved the hulking Epson ET-3830 printer/scanner upstairs and can recycle the Canon scanner.
2023-03-31
LED Shoplight Conversion: First Failure

Having started replacing the fluorescent shop lights with LED tubes back in 2016, this was only a matter of time:

Shop Light – failing LEDs

The next morning the dead section lit up again, albeit with a dim ring at its right end. I think one LED in that string failed open and darkened the whole string, then failed short under the voltage stress, and is now quietly simmering in there with slightly higher than usual current.

The lights over the workbench weren’t in the first wave of conversions, so they may be only four years old.

For sure, they have yet to approach their 50000 hour lifetime …

2023-03-24
Miroco LED Floor Lamp: Driver Transistor Failure Redux

Last July I replaced the driver transistor for the cool white LED strings in our Miroco floor lamp. Apparently they got a bad batch of transistors, because the warm white LEDs suddenly stayed on while the lamp was turned off:

Miroco floor lamp – warm LEDs on while off

Confirming the diagnosis, the cool white LEDs worked fine with the light turned on:

Miroco floor lamp – all-LED mode fail

With nine spare SI2306 transistors in hand from the last time in this rodeo and minus the sticky adhesive foam covering the PCB, replacing the other driver transistor was no big deal, whereupon the lamp once again worked the way it should:

Miroco floor lamp – restored warm LEDs

While I was in there, I spotted a dent in the input filter cap:

Miroco floor lamp – OEM capacitor

Most likely I squished a wire between the cap and the U-shaped steel strut joining the two halves of the pole. I relocated the replacement cap off the circuit board into an open space with a bit more room:

Miroco floor lamp – recapped

The fragile wires running to the lamp head got their own sheet of silicone tape (not shown here) to isolate them from the U-strut:

Miroco floor lamp – LED wiring

Tuck all the wires back inside, snap the housing together, and it should be good for another uhh half year or two.

It’s hard to be sure about such things, but I now have eight spare transistors …

2023-03-23
Craptastic Kitchen Scale: Button Sensor Tweaks

The four control “buttons” on the Smart Heart kitchen scale are copper-foil tabs that sense the presence of your finger though about 5 mm of white plastic and glass:

SmartHeart 19-106 Kitchen Scale – top view

The main failure mode seemed to come from the microcontroller locking up and refusing to recognize any of the buttons, most annoyingly the On/Tare button, while continuing to measure whatever weight was on the scale with whatever zero point it chose. Recovery involved waiting until the thing timed out and shut itself off.

The two buttons on the left select Kilocalories for any of the various foods arrayed around the display. Depending on how it jammed during startup, it might display the Kilocalorie value for, say, sugar, while ignoring all button presses. As the manual does not mention any way to return to weights after activating the Kilocalorie function, other than turning it off, it’s not clear recognizing the other buttons would be much help.

Because we have no use for those functions, I unsoldered the wires to those sensor pads and it no longer jams in that mode:

SmartHeart 19-106 Kitchen Scale – PCB detail

The alert reader will note the PCB legend says I have unsoldered the ON/OFF and UNIT wires. If one believes the silkscreen, the PCB dates back to 2015, so it now carries a reprogrammed microcontroller with functions that no longer match the silkscreen.

The overall soldering quality resembles mine on a bad day.

With those out of the way, the scale still jammed and refused to recognize the remaining two buttons. I wondered if it was somehow sensing ghost fingers over both sensors and waiting for one to vanish, so I added a shield ring around the power tab:

SmartHeart 19-106 Kitchen Scale – shielded sensor

That reduced the sensitivity of both sensors to the point where they pretty much didn’t work, without reducing the number of jams.

So I tried increasing the sensitivity of the power tab by replacing it with a larger copper foil sheet:

SmartHeart 19-106 Kitchen Scale – larger sensor

That definitely got its attention, as it will now respond to a finger hovering half an inch over the glass, as well as a finger on the bottom of the case: it can now turn on and jam while I pick it up.

More tinkering is in order, but it’s at least less awful in its current state than it was originally, so I can fix a few other things of higher priority.

2023-03-21