Oscilloscope

http://blog.tlb.org/oscilloscope

by jlhamilton • 16 years ago

108 30 16 years ago

blog.tlb.org

swombat• 16 years ago

Comic Sans in an image.

Bold, I like it.

eru• 16 years ago

It _is_ a comic.

garply• 16 years ago

tlb, your site is blocked by the Chinese firewall. What did you do to deserve that?

jrockway• 16 years ago

It's hosted on Posterous.

tlb• 16 years ago

I think I'm happy about that. Block away, dear leaders.

blasdel• 16 years ago

I've noticed that after being zapped like this, a lot of electronics manufactured in the last decade often just need to sit unplugged and self-discharge for a while. Real frustrating when you uncable it, fill out the paperwork, throw it on the cart, and take it down to maintenance, only to find that in a week when they get around to dealing with it shit starts working on its own.

Real common with power supplies that just don't work after an abrupt building power outage, but I've had it happen with protection circuits on ethernet and firewire ports too (though it took a lot longer).

dfox2• 16 years ago

In case of sensitive HF inputs (eg. oscilloscope inputs) there is not much you can do about protecting them from overvoltage without significantly harming sensitivity or bandwith. In most cases such things are designed such that something relatively cheap blows up and can be easily replaced. But that something is usually input amplifier itself (overvoltage protection diodes that are fast enought tend to be more expensive and will also burn out so they are not used). It is worth to note that input amplifier transistors are cheap compared to whole scope, not compared to anything you would call cheap.

But miniaturization (and also precision requirements) tend to make replacing such things extremely labor intensive, so it might be more cost effective to simply throw the whole thing away.

Retric• 16 years ago

This seems like the type of thing you would have some sort of replacable card for. Assuming it's a fairly common problem.

CamperBob4• 16 years ago

There are actually several ways in which LeCroy could have protected the input against moderate overvoltage and ESD, such that repairs could be made without replacing the input hybrid. If nothing else, the guy could buy another half-dead scope on eBay for a couple hundred bucks, fix his bad channel, and have a near-complete parts donor left over for future repairs.

If he's the sort who's afraid of replacing the battery in his iPhone, he has no business monkeying with oscilloscopes and such anyway.

samlittlewood• 16 years ago

PolyFuses/resettable fuses (http://en.wikipedia.org/wiki/Resettable_fuse) are often at the root of that sort of behaviour.

cake• 16 years ago

This trend is really depressing me. Most of the time it's cheaper to buy new stuff than to actually repair it.

This weekend I was trying to repair some bike's wheel, some spokes (4) were broken and needed to be changed, I called the bike shop and the guy told me he doesn't keep a stock of spare parts anymore. That he would have to order them by a box of 100 for me. If I let him repair the wheel (having only minor damages) it would cost me more than to buy a new one.

slug• 16 years ago

Save that broken wheel for next time repair ;)

blackguardx• 16 years ago

If you were living in China where these things are built by hand, it would probably be a little cheaper to repair than to replace. In countries with high wages, repair shops can't compete with cheap foreign goods. It is sad, but at least you don't have to pay ten times more for a new one.

duncanj• 16 years ago

Try another bike shop. Mine (in USA) will fix spokes and true a wheel for $20.

sophacles• 16 years ago

That makes no sense to me. A decent wheel costs $70 and of course good ones way more. A spoke costs a couple bucks (tops), so with a decent labor rate, the guy could charge you $35 for the repair. I bet you could find someone to fix it for you.

I wonder if the shop owner stopped carrying repairs because customers are so used to the "disposable everything", that they just assume repair is alwas impossible, and anyone who offers to do it is some sort of scam artist.

Of course,

andrewvc• 16 years ago

That's just not normal, a lot of shops would actually prefer to repair the wheel if they have a larger profit margin on labor than parts. Check some more bike shops, I'm sure you'll find one that'll do it for a reasonable price.

Alternatively, you could learn to do it yourself, though you do need a truing stand. If you live in a large metro area, there are places like LA's Bike Kitchen, where expensive tools like truing stands are available free for use (donations highly encouraged), and volunteers will tell you how to fix it yourself.

pmccool• 16 years ago

> Alternatively, you could learn to do it yourself, though you do need a truing stand.

It is a useful skill to learn, and instructions are available online. You don't even need a truing stand, just leave the wheel in the frame and use the brake blocks as a guide. It's not ideal, but it's workable, and the price is right.

blhack• 16 years ago

Ack, the guy either lied to you or you were at the wrong bike shop. Try and find one with some higher-end mountain bikes and they'll definitely have spokes.

rman666• 16 years ago

If I didn't just get my arduinoscope working (http://code.google.com/p/arduinoscope/), I'd probably ask where your trash dumpster is located and I'd be there on 3/23 :-)

nas• 16 years ago

Neat. I'm pretty happy with my ultra-cheap Owon (http://www.saelig.com/PSBEB100/PSSA002.htm). For some more money you could have a Rigol, which I hear are very good (they make the low-end Agilent scopes).

Having a digital storage scope is a huge advantage in certain situations and I'm happy to have a cheap DSS rather than a higher quality used analog scope. Also, I wrote some software to do spectrum analysis on the PC, something that you couldn't do with an old analog scope.

doc-film• 16 years ago

silly question, but why cant someone who knows how to use a scope simply repair it? Off topic i had a bit of fun the other day fixing a HP pavilion laptop which has a design fault (look on ebay) and all it cost me was some copper pipe and heat sink compound.

bcl• 16 years ago

You need a scope to repair the scope...

CamperBob4• 16 years ago

One who throws away a $2000 item without even bothering to pull the back cover off and look for something obvious like an inline fuse with a Schottky-diode clamp has already wasted far more than that on their EE education.

Must be nice to have more money than brains. Most of us don't have enough of either.

jodrellblank2• 16 years ago

Generosity, consideration and pragmatism, meet holier than thou, jealousy and chip-on-shoulder judgement. Welcome to the Internet.

CamperBob4• 16 years ago

(Shrug) No, welcome to "Hacker News." Supposedly, people here are hackers.

The fellow throwing away the scope is generous, certainly, but other than that, he appears to be the antithesis of a hacker.

noonespecial• 16 years ago

I still have my childhood oscilloscope. Its only 25Mhz but its all analog and dual trace (Phillips PM3214). When I run into something particularly vexing, I still get it out even though I have a 100Mhz DSS now.

Call it a sentimental "security blanket" thing, but it seems like I can feel circuits on that little analog screen.

I've also definitely felt the pain of weird high frequency transients blowing motor controller components. They tend to be high voltage as well. Fortunately I haven't lost any expensive gear yet! Good luck TLB, your bots are awesome.

Oscilloscope

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