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Re: Cracked resistor?

So, a customer sent me a board with the query "whuzzup?"

> > It turns out that there's a resistor in there, which I mostly put in so > that I could monitor current, but I kinda put in as a last-ditch fuse > (1.5 ohm 0603). > > On this board, the resistor is open-circuit with no discernible burning. > Is there some electronic mechanism that could cause this? Or am I just > looking at a faulty part?

I assume you've got your test prods directly on the pads so you know it's not just a dry joint?

X-posted to s.e.r (more appropriate group)

Reply to
Cursitor Doom
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Yes. But making that mistake isn't beyond me, by any means. It's a very well-assembled board (I didn't do it), but well designed, too (I did it

-- and I'm modest, just ask me).

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com 

I'm looking for work -- see my website!
Reply to
Tim Wescott

Plenty of water and the whiskey bottle has been properly drained.

Reply to
Robert Baer

The dissipation power is 200mW max.

So I lower than 0.3A.

If not, it burns !

Reply to
Look165

Hello, and the only similar problem I've encountered is with those sandy-colored dropping resistors (rectangular parallelepiped shaped) that have been used in radios and TVs. They can swell and/or crack over a period of time. Repeated heating and cooling no doubt stresses the resistor material. Sincerely,

--
J. B. Wood	            e-mail: arl_123234@hotmail.com
Reply to
J.B. Wood

Some of those are 'Fuse Resistors', and are designed to fail open if the equipment starts drawing too much current, or if it is running too hot. I replaced hundreds, if not thousands of those in consumer electronics. Some OEMs switched to the Belfuse 'Chemical Fuses', which had a chemically coated element that would flash and vaporize the element at a set temperature.

They were quite common, in spite of Phil Allison's claim to the contrary.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

Not much safety margin for an 0603.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

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