Abusing brick on the rope

Re: ground. Yeah the shell/shield of the supply is connected to earth. Inside the unit I connect 'earth' to ground with a 10 ohm/ 1/2 W resistor. This was undamaged in the returned unit. So I'm assuming no weird ground thing. (but only assuming...)

george H.

Reply to
George Herold
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What is brick on a rope? Where does the rope come from?

Reply to
Steve Wilson

Right, the data I have says the power supply fried... or was hooked up wrong or... But most of the damage was to the PS inputs.

George H.

Reply to
George Herold

Hi Mikko thanks... Earth and ground, (Earth being terminal on my AC wall outlet and ground being the case of the instrument.) are joined with 10 ohm R which (as far as I could tell) was undamaged.

George H.

Reply to
George Herold

A brick on a rope is a desk top power supply, as opposed to a wall wart, which plugs right into the wall with no intermediate AC power line. Typically they have more power.

George H.

Reply to
George Herold

Could it be the + and - were reversed? That would reverse bias an damage that LED. Is it one connector, or separate screw terminals? In the last case do you have (or should you have) diodes in the supply lines?

Reply to
<698839253X6D445TD

Right, I thought that till I found the LED's can take 80V in reverse. (There are no reverse bias safe guards on the PS input... ) It's (I think) a DIN 5 connector... I was trying to plug it in backwards or sideways, but it was not possible... well very hard.

Hey the professor still has the failed brick on rope, so I'm having that sent back.. I'll check it out and then crack it open. I'll post pics if I find anything interesting.

George H.

Reply to
George Herold

George Herold wrote in news: snipped-for-privacy@googlegroups.com:

You could build an inline "minibrick" -15V supply to hang on the end of a standard well made supply, and have a pass thru output cable pair that gives you both. I know that sounds odd, but I would put more faith into a more common off the shelf robust single output supply and your in- house made add on than apparently what you chose. They sound like they may be the problem.

Reply to
DLUNU

Steve Wilson wrote in news:XnsA9705E7E0A0A7idtokenpost@

69.16.179.23:

You have never heard the term "wall wart"? This is like that.

A small "brick" type power supply (usually in a plastic case) in an inline configuration. ergo: "a brick on a rope".

Reply to
DLUNU

Lol! Have you done an internet search on "brick on a rope"?

Rick C.

Reply to
gnuarm.deletethisbit

Usually simply called a power supply brick. Lots of things come in brick form.

Rick C.

Reply to
gnuarm.deletethisbit

Are they in Florida (lightning capital of the world)? Did any other gear in their lab go out at the same time?

Jon

Reply to
Jon Elson

Use a big resistor, they are less likely to flash over in a crazy event.

Jon

Reply to
Jon Elson

Well, most SMPS's have some small capacitor bridging from the primary side to the secondary side of the transformer, to drain the pulses coupled across the primary-secondary capacitance. If this cap fails, and any part of the powered equipment is connected outside, it can cause a shock hazard or excessive current draw. If lightning hits the mains, it WILL cause high voltage on the equipment, and if that gear is connected to anything grounded, there's not much limit to the current available.

Jon

Reply to
Jon Elson

It would not be a bad idea at ALL to have the school check all equipment used at that bench or whatever for power supply faults, bad grounds, open grounds and whatever.

I got knocked on my rear (literally) by an open ground in my lab at work when I had a scope and logic analyzer hooked up, and touched something that was connected to my computer on a properly grounded outlet. I have NO IDEA how long the ground on that outlet had been in that condition.

Jon

Reply to
Jon Elson

most outlets here have no ground so if you touch ground and anything with a smsp you get a shock, but it is only a tingle

Reply to
Lasse Langwadt Christensen

** It should be pointed out that such caps are required by regulation to be special class Y types of strictly limited values - like 1000pF or 2200pF.

Failures are extremely rare.

Wait till GH gets to actually examine the "brick on a rope" concerned.

It just might turn out to have nothing wrong with t.

.... Phil

Reply to
Phil Allison

RPI on the banks of the Hudson. I was thinking, it was bad to post the name, but hey students are my final 'beta' testers. my hat's off to you. George H.

Reply to
George Herold

+1, until then it's guesses.

NT

Reply to
tabbypurr

Hmmm, I haven't thought nearly enough about what happens if every thing is floating (for some reason). I figure to touch gnd lightly and let the 'scope or other piece of measurement apparatus define it.

That's mostly worked so far. :^)

George H.

Reply to
George Herold

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