Test Equipment Anonymous (TEA) group therapy thread

[beanflying]

I had had some boots from tearing down TV's as a kid so I learned quickly to not poke the HV and Caps without shorting them ( thanks Mr Hunter my early Electronics teacher for the shorting 'tip', weird bloke drove a hand painted canary yellow Singer  ). The first really nasty one I got was sitting at a bench at an early job when I got a kick and it threw me off the stool onto the concrete floor. Arm and chest pain compounded by the skull cracking on the floor was a wake up to make sure gear you are 'working in' is unplugged not just turned off at a switch on it.

ELCB or similar might have reduced the kick but well before they were in common use.

[med6753]

In my catalog of stupid pet tricks: I wanted to observe a lissajous pattern on a Heath scope. That's where you place an AC signal on the vertical and horizontal and measure the phase shift. Didn't have a function generator. No problem, I'll use mains voltage. What I didn't realize is that I swapped hot and cold between the vertical and horizontal creating a dead short. As soon as I made the last connection there was a bright flash and bang and then silence. Luckily one of the test leads had a weak link and acted as a fuse. There was no damage to the scope or myself. 

[bd139]

Hahahaha that's quite funny. And you were lucky 

3d printer just arrived  . No time to assemble it until the weekend 

[beanflying]

Hahahaha that's quite funny. And you were lucky 

3d printer just arrived  . No time to assemble it until the weekend 

Should only take 2 hours max to get it done. No need to sleep 

[Mr. Scram]

Hahahaha that's quite funny. And you were lucky 

3d printer just arrived  . No time to assemble it until the weekend 

You bought one? Which one?

[bd139]

Ender 3. Took advantage of an eBay 10% off voucher so snagged the whole thing for £136 which is pretty damn cheap!

2 hours ... maybe can squeeze that in 

[beanflying]

Ender 3. Took advantage of an eBay 10% off voucher so snagged the whole thing for £136 which is pretty damn cheap!

2 hours ... maybe can squeeze that in 

Tom running in the background for good extra waffle and fast forward as needed will get it down from the 3 and a bit hours 

[bd139]

Thanks - have skipped through that one already. Have notes written up

[Zucca]

When I was 12, I open the broken cable switch for a 220Vac 40W bulb light.
I then grab the two cables with exposed copper and let them touch, It was fun to see sparks and see the light slowly glowing.

I then attached one cable to the metal bench press of my father, and then I was hunting for spiders to put on the bench.
I still remembeer the spiders smoking under some little copper wires.

What my son will do?

[xrunner]

Thanks - have skipped through that one already. Have notes written up

Post a lot of pics so we can criticize every minute detail of your assembly.

 

[bd139]

Hahaha. Started assembling now as it’s lunch time here.  I will eat later 

[tautech]

Thanks - have skipped through that one already. Have notes written up

Post a lot of pics so we can criticize every minute detail of your assembly.

 

And witness exactly when the P finger comes into play ! 

[xrunner]

... I will eat later 

I seen to have remember myself saying that in the past when using the machine ... 

[bd139]

Well that was easy.



To do:

1. Cable management. Need to check everything and tape the ribbon cable to the chassis.
2. Friction adjustment on all three axis.

I am very impressed so far. Nicely engineered!

Back to work ....

[Zucca]

Well that was easy.

Oh no! down in the hole with the rabbit.

[xrunner]

Lookin good - nothing can go wrong. 

[bd139]

Watch me burn the house down next 

[xrunner]

Watch me burn the house down next 

Now that you have it you can make a holder for a small fire extinguisher to put next to it.

See how valuable it is already? 

[bd139]

I've already got a powder extinguisher next to it 

Edit: it's printing... doing test dog. Bed adhesion worked straight up! About 15 minutes in.

[Brumby]

No progress report for nearly an hour...

Has there been any activity with Emergency Services in BD's area?

[bd139]

Nah all good here





50% printed so far 

Haven't futzed with any settings. Set PLA to 200oC which is bang in the middle of the range. Bed on 45oC

[mnementh]

Does the electric fence cause any interference or noise issues?

Wouldn’t think so and data checksums should take care of that. All the mast data cabling is shielded CAT 5E and everything is earth bonded.

I’d be more worried about weird corrosion issues caused by localized disruption of the earth/atmosphere ion exchange.

On the farm where I was growing up, the toolshed was a surplus Quonset hut from Seneca Army Depot (had their ID sprayed on every galvanized steel panel). On the corner where the ground stake for the fencer to the main pasture was driven into the ground, it developed a truncated elliptical patch of bright red rust about 2 feet wide & 3 feet high; its centerline followed exactly the axis of the two points where the HOT & GND wires passed through the windowframe. I probably saw that rust patch a thousand times and never thought anything of it; I was always passing on my way to do something in the field beyond.

Then we installed a 2nd fencer in the opposite corner of the Quonset hut to drive a fence around another field. THAT side of the hut was adjacent to the grassy are where I most often played; over the next several months I noticed the spray-painted lettering grow a raised layer of the same red rust, eventually spreading out into an almost identical elliptical area of rust to that on the opposite corner of the structure.

I brought it to my grandfather’s attention one afternoon, when I made the connection; he thought I was pranking him at first. “I find that highly suspect.” was his response, until I literally dragged him out to see.

When he noticed a thin beard of rust on the lettering of the adjacent panel, then he believed my tale; running his hand over the rough surface all he could say was “Huh... crazy electrons anyways...”

After that he attacked the rust spots with a descaling grinder and painted the panels, then moved the ground stakes out about 20 feet away from the building, which seemed to resolve the issue.

But I never forgot that lesson: Just because you can’t SEE electrons, doesn’t mean they aren’t doing weird shit all around us all the time.

*mnemories*

[tautech]

That’s interesting mnem   
Dunno what was going on there ? 

In the nearly forty years of using mains powered units the one thing I’ve never scrimped on is the fence earth so to get down deep to the water table.
Even though it might be an earth connection it should still be insulated all the way to the earth peg/s as when there’s a big short somewhere the peg can obtain an elevated voltage that if nothing else can be a bloody nuisance for all. Especially so if the installation is nearby a milking shed or some animal yard or barn.

Normally elevated earth peg voltages are dealt with by adding more pegs but in the last few decades I’ve used a single full 20ft length of galv pipe to get down deep and be sure to be in the water table.
IIRC I got ~3.5kV on that fence wire when I checked it, piss ant earth and you get nutthing like that 2km from the unit.   

[Martin.M]

I have lost a round of TGT (test gear tetris): the cabinet is loaded and there is a rest.

again 

[mnementh]

I think a lot of us had a start like that. I tried to build stuff with discarded valve radios and discovered that some of them had live chassis pretty quickly  . Also that transfomers and selenium rectifiers liked to catch fire. My parents bought me a Radio Shack kit after I smoked my nan's kitchen out and banned me from mains stuff

Same here. Mom was a great supporter of my generally “live in the great outdoors” youthful lifestyle; while grand-dad had a big color console TV which was the holy altar of religious Sunday afternoon ballgame-watching with my uncle Frank and occasional neighbors, in our home we never had ANY TV until I bought an old 13” tube-type B&W set at a yard sale for $2.

I cleaned out the dust elephants, fired it up & noticed a periodic “kraaak-kraaaak!” as the CRT anode arced to the metal frame of the set along some unknown residue trail; I turned it off and bright boy that I was, DID unplug the set before I reached in with alcohol-damped rag to clean off the residue.

”KRAAAK-KRAAACAAAAKKKK!!!” it went, discharging the anode through several fingers; fortunately the rag went flying when I jerked my hand out of the set, because I didn’t notice it burning on the floor of the garage for a good 30 seconds as I was busy sucking on tingly fingers.

Once I’d recovered my wits, I contrived to attach an alligator wire between metal frame and a long thin screwdriver; which I then gingerly probed under the anode cap until I was satisfied no angry pixies remained lurking. Years later I would be shown the same exact technique by Mr. Basche, the high-school AV Shop foreman who gave me my start in electronics; this of course served only to reinforce my teen-ager’s conviction that I was always the smartest guy in the room... 

After successfully cleaning the back of the CRT, I was rewarded with lovely dancing pixies on the front of the set, but could not pick up anything on any VHF channels, but a few ghostly images on UHF. Further digging revealed a dirty grey tube under the tuner assembly that didn’t light up (IIRC, a 6AU6...?) and so I scoured yard sales the next few weeks until I had a handful, which I took to the local Red Ten and tried on their people-checker tube-checker until I found one that was the same, but had marginal emission and another that was a letter different but tested good.

I scurried away home with my prize, and still out of breath from pedaling as hard and fast as I could for 16 blocks, still tried the questionable exact-match tube first. Unlike the original, it glowed faintly; after a couple minutes I found I was able to tune in the local CBS station but had very poor vertical sync (Well, to me at the time it was just squiggle-screen).

With some level of trepidation, I unplugged the toasty-warm set and carefully replaced the tube with the one that was one letter off; I was now quite leery of touching anything metal inside the thing just after power-off, but reasoned that it used the same setup on the tube-checker as the correct tube, so shouldn’t be able to harm anything, and as long as I only touched glass it shouldn’t light me up either.

When the operation was complete I was rewarded with a lovely, crisp image of baseball highlights on the 6 o’clock news; tuning around the dial brought in all the big three networks, and after discovering that you needed a bow tie for UHF I was able to get some weird Italian-sounding stuff as well as religion channels and the local FOX affiliate, which would become the centerpiece of “me & mom” times watching reruns of Star Trek and Wild Wild West...

*sigh*

*mnore mnemories*