Straining the hr/min dimensional nonsense out of the slope suggests the camera averages 550 mA and 1.9 W. Derating those by a few percent to account for the recharge efficiency might be in order, but they’re surely in the right ballpark.
Unfortunately, an analog meter isn’t up to displaying anything meaningful for this nonsense:
Admittedly, that’s a 50 ms pulse, during which an analog meter would barely twitch. The vertical scale is 5 mA/div, so the highest peaks exceed 35 mA, more than twice the tube’s recommended “14-15 mA”.
That’s at 10% PWM, close to the threshold below which the laser just won’t fire at all. The power supply must ramp up to produce enough voltage to fire the tube while simultaneously limiting the current to prevent the discharge from sliding down the negative resistance part of its curve.
Apparently this supply isn’t quite up to the task.
A 10 ms pulse at 50% PWM gives the supply enough time to stabilize the current:
The 14-ish mA at the tail end of the pulse (note the baseline offset) matches my previous 13 to 14 mA measurements as closely as seems reasonable. That 2 ms of hash on the leading edge suggests the start of each cut or engraving line will be a bit darker than you might expect.
Another 10 ms pulse, this time at 99% PWM:
The peak 24-ish mA matches the previous measurements. Note that the peaks in all the previous pictures exceed the 99% PWM current level.
AFAICT, all PWM values below about 25% produce equivalent results: random current spikes with unpredictable timing and amplitude. Changing the PWM value does not affect the (average) tube current or laser output power in any predictable way.
Some samples to illustrate the point, starting with a different 50 ms pulse at 10% PWM than the first one up above:
A 50 ms pulse at 15% PWM:
A 50 ms pulse at 20% PWM:
A 50 ms pulse at 25% PWM:
Now, that last one is different. After the hash during the first 8 ms or so, the power supply actually produces a stable 5 mA beam current, which is roughly what I measured using the power supply’s meter.
However, the other three are pretty much identical: the 10% PWM pulse does not delivers half as energy as the 20% PWM pulse. The waveforms may be different, but not in a meaningful or consistent way: the two 50 ms 10% pulses are different, but you’d (well, I’d) have trouble separating them from the 20% pulse.
The first several millisconds of any pulse will consist of randomly distributed spikes with very large tube currents.
For PWM values greater than 25%, the tube current will settle down to the corresponding current after 5 to 10 ms. Before the current settles down, the tube will be firing those random spikes.
For PWM values less than 25%, the tube current never settles down: the entire pulse, no matter how long, will be short, high-intensity spikes, without a consistent DC-ish level.
No matter what an analog meter might show.
I have no way to know if this power supply is defective, but I’ll certainly ask …
I think the Total job laser on time line says the power supply failed after firing the laser for a little over eight hours. The OMTech manual says the laser tube should last 1000 to 2000 hours (low vs high power), which suggests I should stock up on power supplies.
Its replacement just arrived:
It (bottom) seems to be a knockoff of the original ZYE Laser supply (top), with a similar model number and a “serial number” resembling a date from last year. All the connectors matched up, which isn’t too surprising.
The three most interesting inputs:
L = controller’s active-low L-ON enable output
IN = controller’s PWM output
P = jumper to G (circuit ground) — not water flow sensor
Also note the two AC power-line terminals directly adjacent to the TEST button, then consider insulation and stand-off distances before poking the button with your index finger.
The power supply has a digital current meter, so I plotted output current against PWM input:
Taking more points at the low end, with vertical bars indicating single-digit flicker on the meter:
I have little reason to believe the meter reading indicates the true current with any accuracy and I know CO₂ laser output power does not scale linearly with the current.
But it’s cutting again, which is a step in the right direction.
It’s a Hyde Edge Recharge vape pen or it could be a counterfeit. You (definitely not me) get “up to” 3300 puffs from the 10 ml container, with 50 mg of nicotine ensuring you can’t get enough and will come back for more. Although I don’t follow the market, “disposable” vape pens can still contain the fruity flavors prohibited in refillable pens, with the added decadence of throwing the whole thing away when the tank runs dry:
My admittedly inexperienced eye says the “tank”, which is really just a fiber cylinder soaked in fruity juice + nicotine, still has plenty of hits remaining.
The Basement Shop may never smell the same again.
Of more interest, the silvery lump wrapped in a white felt strip is a 600 mA·hr lithium cell that slurped 406 mA·hr through its USB Micro-B jack when I recharged it. Perhaps the uservictim sucker tossed it when the battery “died”, being unable / unwilling / ignorant-of-how to recharge it? The yellow aluminum case seems faded on the mouthpiece end, but that might be a stylin’ thing.
A closer look at the electronics payload:
The two red wires over on the right went to the coil in the draw tube to the right of the “tank”. Not being interested enough to care, I wrecked the coil while extracting the rest of the contents. Comfortingly, the red and black wires from the PCB go to the positive and negative battery tabs.
The black felt disk covers an anonymous pressure sensor activating the coil during each puff. With four pins, the sensor must be far more complex than just a switch, but nowadays puff sensing could require an entire ARM microcontroller.
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:
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.
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:
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 confirmed my suspicion:
We are afraid that the laser power supply is defective
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.
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!