
Oscilloscope - jlhamilton
http://blog.tlb.org/oscilloscope
======
cake
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.

~~~
andrewvc
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
> 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.

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blasdel
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).

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

~~~
dfox
Many components of oscilloscope have to be physically close (because of
delays, signal loss and interference) to input (ie. on same card) and in case
of small 2-channel scope it can easily be third of whole scope (and more than
third of price). Larger scopes tend to have replaceable cards for inputs, but
such scopes are too large (and of course expensive) for most applications.

------
rman666
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
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.

------
noonespecial
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.

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

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

------
swombat
Comic Sans in an image.

Bold, I like it.

~~~
eru
It _is_ a comic.

------
CamperBob
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.

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

~~~
CamperBob
(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.

~~~
charrington
This is Trevor Blackwell we're talking about. Perhaps you should be careful
before casting aspersions. <http://tlb.org/>
<http://en.wikipedia.org/wiki/Trevor_Blackwell>

Ad-hominem attacks are not the kind of thing Hacker News is about. Please keep
that in mind.

~~~
CamperBob
I really don't care what he built by duct-taping motors to PC-104 boards from
the back of Nuts-n-Volts. If he throws away scopes and iPhones he's not
someone who impresses me as a Hardware Guy.

Edit: keep in mind that his cartoon is mostly a bunch of whining about how he
_can't_ do this and _can't_ do that because of how modern electronic equipment
is made. Meanwhile, a friend in Portugal just used his homebrew wire-bonding
machine to repair an 18 GHz YIG-tuned oscillator for me. (He failed this time,
which is damned rare for him, but he sure didn't balk at trying.)

I do respect his generosity, though -- hopefully, some talented kid's going to
get a nice present out of it. I try to help out in the same spirit when I can,
because I benefited from similar generosity as a newbie.

------
doc-film
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
You need a scope to repair the scope...

