On 11/17/2014 5:27 AM, John Woodgate wrote:
In message <052386ecbaec46bb9a46af06a46b1...@sehste15d1be4.hs20.net>,
dated Mon, 17 Nov 2014, Charlie Blackham
<char...@sulisconsultants.com> writes:
The NRTL insist on short-circuiting the single 560R current limiting
resistor and I am unable to find any evidence that thick-film or
thin-film surface mount resistors can fail short-circuit as they
appear to fail open-circuit
They are citing the standard, which doesn't have an exception for not
shorting SM resistors. It's probably too late to take them into
account in 60950-1, but this should be considered for 62489-1, if it
hasn't been already. Will the resistor manufacturers give assurances
that S/C failures do not occur?
I'd say any problem would lie in soldering techniques; how many fires
are due to solder bridges?
FWIW department: I once had an ADSL modem board I'd modified for testing
catch fire in my hand. My manager came into the lab and yelled at me
several times --I was watching the spectrum analyzer -- before I
noticed. (grin)
I'll grant that a "wall-wart" is not as limited as a button cell; in my
case the resistance of the already carbonized board was a continuing
source of ignition. CAN a button cell set fire to a board?
Cortland Richmond
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