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.

Category: Electronics Workbench

Electrical & Electronic gadgets

OMTech 60 W Laser: Failed HV Power Supply
Setting up a piece of MDF and hitting the Frame button produced a lightly scorched line around the part perimeter, plus a slightly diagonal track leading from / to the Home position in the far right corner:

Fire while framing tracks

Doing another pass with LightBurn’s rubber-band frame produced the faint dotted circle.

Huh. Didn’t useda do that.

The laser should not fire while framing and, having just installed LightBurn’s 1.2.01 update, suspicion instantly fell on the most recently changed thing.

Which turned out not to be the case, as LightBurn’s tech support pointed out:

This is generally an indication of a failed high-voltage power supply, not a software issue.

OMTech’s support requested a video of the equipment bay, which didn’t seem like a useful way to convey the situation. Instead, I sent pix.

This picture shows the status of the 60 W laser power supply while the laser is incorrectly firing:

OMTech 60W Laser – uncommanded framing fire

The power supply has two LEDs on what looks like, but is not, an Ethernet jack near the bottom:
- Orange P LED: good water flow
- Green L LED: controller’s PWM signal
The LASER orange LED near the top turns on when the HV output is active and the laser should be firing.

In this case, L LED is off and the LCD shows “Laser signal OFF”, but the LASER LED is on and the LCD shows 2 mA beam current: the laser beam is ON, even though the controller has not activated the PWM signal.

Not only that, but I discovered the laser would fire while framing even with the lid up and the “safety interlock” sensor active.

Totally did not expect that.

For comparison, the power supply status during a manual pulse at 49% power:

OMTech 60W Laser – manual pulse 49%

In that case, the L LED shows the PWM signal is active, the LASER LED is on, and the LCD shows 14 mA of current to the tube. That’s how it should work.

Although the function of the TEST button seems very lightly documented, pressing it did not turn on the output (the LASER LED is off), despite lighting the L LED:

OMTech 60W Laser – Test button pressed

OMTech confirmed my suspicion:

We are afraid that the laser power supply is defective

A replacement should arrive in a few days.

Protip: always practice laser eye safety.
2022-07-28
Kensington Expert Mouse Scroll Ring: More Data Points

A note from Alan adds more data about troubleshooting problems with the classic Kensington Expert Mouse trackball scroll ring:

I have two comments and a question: first I made the mistake of purchasing 4 used expert mice on ebay etc and each had a different problem but 3 of 4 also had faulty scroll rings. 2nd: one of them was dated 2020 (a wireless version). so they definitely haven’t fixed this issue and it’s very wide spread (or maybe why shady sellers decide to part ways with their trackballs).
question: from reading across your quotes it’s not clear but it seems like there is no real consistent fix to this issue nor a really strong conclusion as to what causes it? My futzing with a couple of these does seem to suggest that alignment of the ring makes a difference but not a lasting one.

As far as the alignment non-fix goes, tweaking the detector position just changes the amount of light passing through the wrong side of the reversed IC, without solving the problem. That’s what we’ve all done, with essentially the same results: feels good, doesn’t last.

Kensington (whoever they are these days) may have fixed the problem with a different quadrature detector oriented in the proper direction, but that’s not something we civilians can accomplish.

It should be possible to unsolder the reversed detector (if, indeed, it is), aim the lens (if that’s what it is) at the emitter, then somehow resolder the leads to the same pads. Perhaps flip it to put the leads on the top, away from the PCB, secure it with a generous blob of hot-melt glue, and connect jumpers from pads to leads?

So far, the two new-ish units on my desks continue to work well, depriving me of sufficient motivation to dig into my junkers.

If anybody is willing to hack their defunct trackball, please let us all know what happened!

Because you may be reading this in our future, comments on this particular post will probably have been disabled to reduce the attack surface for spammers. Send me an email / use the comment form (linky over on the right), or comment on the post of the day and I’ll sort it out. Thanks!

2022-07-27
Gentec ED-200 Absorber Surface Damage

Having grossly exceeded the Gentec ED-200 maximum power spec, I wasn’t surprised to see this when I finally tucked it back in the drawer:

Gentec ED-200 surface damage

The 0.5 mm scale suggests the damage came from a defocused 2 mm beam or the hot central part of a larger beam, but I obviously wasn’t paying enough attention at the time.

The rest of the surface seems undamaged, so this may have been one of those inadvertent long-duration pulses or several shorter shots in one spot.

2022-07-14
Miroco LED Floor Lamp: MOSFET Replacement

The only LED floor lamp I bought which didn’t require extensive hackery to lower the business end to suit Mary’s preferences failed after two years. The warm white LEDs continued to work fine:

Miroco LED Floor Lamp – warm white LEDs

But the cool white LEDs were permanently on at a very low level and did not respond to any of the brightness controls:

Miroco LED Floor Lamp – cool white LEDs

You can’t tell, but the cool whites are on in the first picture, too.

The symptoms suggested the driver transistor for the cool whites has failed partially on, although I’d expect it to be either a dead short or completely open.

The lamp being a year or more out of warranty and having come from one of the myriad Amazon sellers banned during the Great Paid Review Purge, there’s nothing to do but remove the four screws from the back of the control lump and see what’s inside:

Miroco LED Floor Lamp – PCB packing

How this was assembled I cannot say, because the three wires going to the LED head (on the far right) have less than an inch of slack. Maybe they pulled wire into the head while screwing things together?

I think the HC8T1212 microcontroller sticking out of the foam is a distant descendant of the Motorola (remember Motorola?) MC68HC05 family. I’m mildly surprised they didn’t use a 32-bit ARM / MIPS / whatever micro, with WiFi capability and a strong desire to siphon my private bits.

The two pieces of closed-cell foam seemed firmly glued to the PCB, but eventually yielded to brute force. Scraping brittle yellowish goo off the right end revealed the LED ballast resistors and the wire labels:

Miroco LED Floor Lamp – ballast resistors – LED wiring

Note the bar-taut Y- wire going to the warm-white (“yellow”?) LEDs.

The black foam left a mess over most of the PCB, but diligent scraping eventually revealed the driver transistors:

Miroco LED Floor Lamp – A6SHB MOSFETs

You can’t read it, but the topmarks were A6SHB: an old Siliconix (remember Siliconix?) SI2306 30 V / 3 A MOSFET. Turns out you can get new-production SI2306 transistors from the usual Asian foundries through eBay, which I did.

It’s not the neatest soldering job ever, but it’ll suffice:

Miroco LED Floor Lamp – A6SHB MOSFET replaced

The colorful wires over on the right added enough length for a pair of Tek current probes:

Miroco LED Floor Lamp – 200 mA-div

The top (cyan) trace is the (repaired) cool LEDs, drawing 600 mA from the 10 V supply, so the 0.5 Ω ballast dissipates 180 mW. The bottom (green) trace is the warm LEDs at 500 mA through a 0.75 Ω ballast for 190 mW. That end of the control lump does feel a bit warm after a while, but nothing out of the ordinary.

Stuff the foam back in place, tuck the longer wires around the edges, snap the cover in place, reinstall the screws, and the lamp is at least as good as new.

2022-07-11
LitUp LED Light Pad: Direct Wiring

Unfortunately, reinforcing the USB Micro-B jack on the side of the LitUp LED Light Pad only delayed the inevitable: the light became erratic even without the slightest touch. The pad consists of three acrylic sheets glued together around the entire perimeter, so there’s no way to get access to the no-user-serviceable-parts within. Apparently, you’re supposed to just throw it out.

On the other paw, it’s already dead, so there’s nothing to lose:

LitUp LED Light Pad – failed USB jack

A little deft razor knife work chopped through the rear sheet without doing any (more) damage to the PCB within. The LEDs can still be convinced to light, but the USB jack is definitely wrecked.

Applying some ChipQuik let me extract the jack without (too much) more damage. Rather than replace it, I just soldered a pigtail USB cable to the obvious PCB pads:

LitUp LED Light Pad – direct power wiring

If I’d noticed that little solder ball, I’d have removed it before filling the cavity with hot melt glue and squishing the cut-out piece of white acrylic in place.

A little black duct tape should keep the wiring stable enough for the foreseeable future:

LitUp LED Light Pad – redirected cable

That was another (relatively) easy zero-dollar repair that should not be necessary.

2022-07-08
BatMax vs. Newmowa NP-BX1 Camera Batteries: 2022
Two years ago, a quartet of new BatMax NP-BX1 batteries performed about as well as could be expected and, by last fall, had deteriorated about as much as expected:

Batmax NP-BX1 – 2021-09 vs 2020-03

In round numbers, the total capacity declined from 3.25 W·hr to 2.5 W·hr, which means a single battery can’t quite power the camera for the duration of our normal hour-long rides. I do not know what voltage trips the camera’s decision, but the batteries definitely shut down sooner.

So, based on their previous track record, I bought another quartet of Batmax batteries. Being that type of guy, I tested both the old (2020) and new (2022) sets:

NP-BX1 – BatMax 2022 vs 2020 – used-new

The blue traces are the C/D batteries from the as-new tests back in early 2020, the green traces are C/D after two years of use, and the red traces are the “new” quartet after their first charge in the Official BatMax Charger.

It looks very much like BatMax is selling used batteries repackaged as new items, because they are indistinguishable from my used ones. They definitely are not the “Premium Grade A cells” touted in the description.

I returned them for a refund and sent the test results to BatMax; they sent “new replacements” even though I said I would not pay for any future shipments. The batteries had a slightly different wrapper, but the test results were still indistinguishable from used batteries. I offered to return the package and was told that would not be needed.

Just a few more batteries for the blinkies.

So I bought a trio of NP-BX1 batteries from Newmowa, an Amazon supplier with a few more vowels than usual, and repeated the exercise:

NP-BX1 – Newmowa 2022 ABC – 2022-06-29

It seems three good batteries now cost about as much as four crap batteries, under the reasonable assumption chargers are essentially free.

Three batteries isn’t quite enough for my usual rotation and, for unknown reasons, one cannot buy only batteries, so in short order I will have two chargers and six batteries.

The consolidated test results:

NP-BX1 – Newmowa Batmax 2022 comparison

The color code:
- Newmowa: red
- BatMax 2020 new: blue
- BatMax 2020 used: orange
- BatMax 2022 new: green + lime
I stopped writing Amazon reviews after having a few detailed-writeups-with-graphs rejected for the usual unspecified reasons. As the Finn put it, “You wanna download, you know the access code already.”
2022-07-05
LED Bulb Life Data Point
A rare trip to the Poughkeepsie Railroad Station provided an opportunity to check out the LED bulbs in the chandeliers:
The 108 bulbs had only one deader (lower left in chandelier C).

I have no way of knowing if they’re the same bulbs from six years ago, but the accumulation of bugs / dust / crud inside the (what I would expect to be) sealed envelopes suggests they’ve been hanging there for quite a while:

Pok RR Station – Chandelier B – detail

The dark cruciform patches might come from failed LED chip strings, although the bulbs all had the same eyeballometric brightness. The patches all seem to have a hard lower edge, so we may be seeing shadows from dust accumulating atop the chips on the PCB.

They’re a definite step up from CFL bulbs, although still not as pleasant as OG incandescent filaments.
2022-06-23