On Monday, December 26, 2011 10:43:05 AM Igor Chudov did opine:
I had, recently, a couple of instances of electronics failing,
seemingly, from cold weather.
1. Netgear GS-108 8 port gigabit switch failed when I left on vacation
and let the house cool to 52 degrees F.
2. Saitek USB joystick on my CNC mill failed when the garage cooled to,
perhaps, 40 degrees F.
Electrolytic capacitors being used at a very small fraction of their
labeled voltage rating will 'deform' and lose capacitance, and cold weather
tends to exacerbate it, often because the pressure held internal
connections to the foil fail at the same time. They will generally exhibit
a high 'ESR' (Equivalent Series Resistance) prior to that, which if there
is enough current to warm the resistance, will exhibit It has to warm up
for 10 minutes before it works right performance. The heat will tighten
the crimp and make a better connection.
Either one might also fail because a microscopic crack has formed around
the lead of a part. Re-warming all the soldered joints adding a small
amount of fresh rosin cored solder might help in that case. I have one of
those saikek game pads but haven't checked it for function in a while, I
could not do sufficiently precise work with its teeny little joystick
buttons.
I am wondering, what specifically could possibly account for those
failures, what mechanism. Thanks.
Those would be the 2 major failure mechanisms. There are others, but
stastistically an extremely rare occurrence in my 60+ years of experience.
That would make me check the capacitors in the netgear, and the solder
joints in the joystick.
Also note that 99.99% of the capacitor 'testing' DVM's do not measure this
ESR phenomenon, the single most important characteristic of a capacitor.
There is a guy, was in Omaha but could have moved, that makes a 'Capacitor
Wizard', sells for $175 (when I bought one for the tv station 15 years
ago), which does measure this. It measures the resistance of the capacitor
with a 100khz test signal of about 80 millivolts. So it can do it in
circuit, power off of course, without making a bad cap good again. And
with that low a signal level, any semiconductors are out of the circuit.
We have a 3 pound coffee can nearly full at the tv station, of teeny little
surface mounted bad caps this thing has found, probably saving us $200,000
in replacement PCB boards over the years since I bought it.
One place to see buy it is:
http://www.suburban-electronics.com/display/CAP1B/Capacitor-Wizard
Google will find other places too. Perhaps saving a few dollars.
But to put this in perspective, at its cost, the router game pad can be
replaced, with enough left over for a 12 pack. ;)
Cheers, Gene
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