Author Topic: Ebay Anti-static Straps - Test First!  (Read 4747 times)

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Online xrunnerTopic starter

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Ebay Anti-static Straps - Test First!
« on: May 20, 2015, 03:13:14 pm »
Just arrived from Ebay - A new anti-static strap. Of course I tested it first - and to   not to my surprise it had a complete open from the snap to the other end. I used a needle to pierce the insulation to isolate which end might be at fault, and it pointed to the snap end. I'm still cutting into it but so far there is continuity from the cut end of the wire to the entrance of the coupling. But what am I seeing there? It looks like some kind of glue - it's not solder.  :wtf:

Be back with another pic when I get inside ...

FYI the seller is sending me a new one of course.

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Offline Asmyldof

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Re: Ebay Anti-static Straps - Test First!
« Reply #1 on: May 20, 2015, 04:27:58 pm »
Are you sure it is an open end?

ESD straps come with a 1MOhm resistor.

Why?

Because connecting yourself to hard ground with 0Ohm and then touching a live wire = OUCH.
Being 1MOhm away from ground still does the job of you not building up floating charge compared to earth, but will not possibly kill you when you touch 300V by accident.
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Offline wraper

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Re: Ebay Anti-static Straps - Test First!
« Reply #2 on: May 20, 2015, 04:35:26 pm »
FYI the seller is sending me a new one of course.
All seems as it should be. 1 megohm resistor crimped to the wire (crimp looks dodgy though). I guess you need to apologize to the seller and pay for the extra ESD strap he sends to you.
 

Online xrunnerTopic starter

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Re: Ebay Anti-static Straps - Test First!
« Reply #3 on: May 20, 2015, 04:40:40 pm »
Are you sure it is an open end?

Uh, yea I'm sure because my Rigol DM3058 says so

Quote
ESD straps come with a 1MOhm resistor.
Well, not this one, at least I don't see it yet. If there is an X-Megohm resistor in the circuit I haven't found it yet. So either way you slice it it's faulty. I just measured the complete cut-off coiled lead and it shows about 13 ohms from one end to the other.

The fault is in the strap clip thingy but I've yet to cut into it, but I will later today.



All seems as it should be. 1 megohm resistor crimped to the wire (crimp looks dodgy though). I guess you need to apologize to the seller and pay for the extra ESD strap he sends to you.

Uh no, it's an open - see above.  :-//
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Offline Asmyldof

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Re: Ebay Anti-static Straps - Test First!
« Reply #4 on: May 20, 2015, 04:46:21 pm »
Well, not this one, at least I don't see it yet. If there is an X-Megohm resistor in the circuit I haven't found it yet.

I can literally see the resistor's butt in your picture, all bare and in view for all. Just sticking out a little from the plastic. It may be broken, or 10MOhm, what's the range on the Rigol?, by accident, but you _have_ found it.
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Online xrunnerTopic starter

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Re: Ebay Anti-static Straps - Test First!
« Reply #5 on: May 20, 2015, 04:48:50 pm »
I just cut into the cap and it's a 1 M ohm R. The crimp is dodgy, that's what the problem is. I've seen this type of construction many times before in Chinese stuff. In order find or fix it you have to destroy the thing because it's all sealed.
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Offline Asmyldof

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Re: Ebay Anti-static Straps - Test First!
« Reply #6 on: May 20, 2015, 05:11:02 pm »
I just cut into the cap and it's a 1 M ohm R. The crimp is dodgy, that's what the problem is. I've seen this type of construction many times before in Chinese stuff. In order find or fix it you have to destroy the thing because it's all sealed.
True enough. But at least they did add the resistor :-)
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Online Ice-Tea

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Re: Ebay Anti-static Straps - Test First!
« Reply #7 on: May 21, 2015, 06:29:20 am »
I just cut into the cap and it's a 1 M ohm R. The crimp is dodgy, that's what the problem is. I've seen this type of construction many times before in Chinese stuff. In order find or fix it you have to destroy the thing because it's all sealed.
True enough. But at least they did add the resistor :-)

yeah. I'd rather measure stuff on my bench with a broken ESD cord compared to a hard short in it.

Offline mcinque

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Re: Ebay Anti-static Straps - Test First!
« Reply #8 on: May 21, 2015, 11:32:05 am »
Quote
the crimp is dodgy, that's what the problem is. I've seen this type of construction many times before in Chinese stuff.

Don't be offended but... I really don't understand why some buy cheap chinese stuff on ebay and then complain about its quality...

Probably you've paid 1$ or 2$ for that strap. What do you expect?
 

Offline Dave

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Re: Ebay Anti-static Straps - Test First!
« Reply #9 on: May 21, 2015, 12:07:13 pm »
Don't be offended but... I really don't understand why some buy cheap chinese stuff on ebay and then complain about its quality...

Probably you've paid 1$ or 2$ for that strap. What do you expect?
There is a difference between a low quality item and one that doesn't do its job at all.
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Offline mcinque

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Re: Ebay Anti-static Straps - Test First!
« Reply #10 on: May 22, 2015, 11:23:39 am »
You're right Dave, but consider that in a dead-simple product (as that strap), there is a very, very small difference between low quality and no quality at all (meaning useless product): you could have snaps that doesn't stay fit (= unusable product) or cable with a broken connection (= unusable product). There is no much else that can happen. So with cheap dead simple products, IMO it's a 50% win or lose game.

Instead, with a DMM for example, you could have a low quality one with no input protection, slow update rate, low accuracy/precision, but that can effectively measure something. For me, that's the difference you're talking about.
 

Offline dom0

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Re: Ebay Anti-static Straps - Test First!
« Reply #11 on: May 22, 2015, 11:46:34 am »
Because connecting yourself to hard ground with 0Ohm and then touching a live wire = OUCH.
Being 1MOhm away from ground still does the job of you not building up floating charge compared to earth, but will not possibly kill you when you touch 300V by accident.

Another reason for the high-resistance of ESD stuff is that it limits the bleed current ; a low-resistance ESD connection would lead to high currents that could destroy very sensitive devices (e.g. laser diodes, unprotected FETs).

That's why, in my opinion, 'hard-earthed' solder station handles/tips are not ESD-safe. Also, they're just impractical for many things.
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