I finally learned to check these first before jumping into the software
or running to the computer store. A good lesson for anyone else
I have a board in the PC -- don't remember what it's called -- that
plugs into mother board and give me 6 more USB ports. I have all of
them being used. Yesterday, all the USB devices connected to that board
stopped working. Figured it was the board or bad connections. Shut it
down and tried pulling it out and back in a few times -- didn't help.
So I pulled out the bard and saw the top had a good 1/16 inch of dust.
Brushed it off good with a dry toothbrush, put it back in and working
Note to self -- try the simple first, dummy.
On 4/28/2015 1:42 AM, Snuffy "Hub Cap" McKinney wrote:
I've got a couple USB ports that are not reliable.
Tried a blast of dielectric grease, figure it works
for spark plugs. Not sure it helped, but at least
I did "some thing".
Christopher A. Young
learn more about Jesus
I've worked in the telephone circuit design for 30 years and we always
lube the connectors. This was done mainly for gold to gold contacts as
they can essentially cold weld after many years making it impossible to
remove the board. In the early days it was a very thin wiping of bee's
wax. But, some people in the field took this to mean dunking it in the
solvent dissolved wax. Today they use a very expensive lubricant from
Monsanto which is mixed with contact cleaner for field use. Also, a
disposable pad it used to clean both the board connector and the
backplane connector to which it is plugged into. It leaves a very thin
but effective layer of lubricant. BTW, these are not greasy and don't
On 04/28/2015 12:42 AM, Snuffy "Hub Cap" McKinney wrote:
Dust should always be cleaned off as it will retain heat...however
unless you are in a machine shop where there would be metallic dust,,
the dust in your home is non-conductive.
The problem more than likely was a poor connection due to tarnish.
When something like that happens on a machine I'm working on...typically
the video card or RAM
I remove the component and clean the contacts with a strip of white
paper. Once I see no more residue on the paper, I reinsert the component
and it usually works fine. I also make sure there is no dust in the
slot, by giving it a short blast of compressed air.
I don't understand. Why didn't you see the dust when you pulled the
board out a few times?
I wonder if it was capacitive coupling between two legs of an IC,
through the dielectric constant of the dust.
Most of chips work on standard basic 5V DC. Between pins dust won't have
much effect electrically. If it were HV then maybe, arcing or what you
mentioned. PCI slots on PC motherboard can tilt when hold down screw is
tightened causing poor socket contacts. Some times have to reshape guide
plate on the board for better seating. Spent almost half a century in
the field. Repaired/modified tons of various logic
board on test jig. Now being retired, my pastime is fixing friend's
neighbor's sick any thing electronics. Only charging for parts I don't
have when needed. Also son's and his buddy's guitar amps. When I went
to work after school there were still many vacuum tubes in use. I am
class of '60 EE. Lived thru electronics evolution(vacuum tubes to nano
Stray capacitance wasn't evident with a VOM. It was with a VTVM, an
oscilloscope, or a DMM. The lead of a DMM may be nowhere near a
conductor with 60Hz, but it can pick up several volts. The unshielded
part of a scope lead is much shorter, but it, too, will pick up 60Hz
from stray capacitance.
Impedances in modern circuits can be much higher than the input of a DMM
or a scope. Distances can be very close and frequencies a lot higher
than 60Hz. In putting together my own circuits, I've had to add
capacitors because of the unforeseen effects of stray capacitance.
If I got moisture in a digital watch, I wouldn't expect it to work. The
conductivity of distilled water is 5 microsiemens/meter. Seawater is a
million times higher. If distilled water stopped a watch, I'd suspect
capacitive coupling. The dielectric constant of water is 80 times
higher than air.
I don't know the dielectric constant of household dust, but I imagine it
could be a lot higher than air if it absorbed humidity. Maybe he OP had
trouble on that day because the humidity in the room was a bit higher
than it had been.
You need to use Monster Products Magnetic Flux Tube® that enhances
internal magnetic fields and Linear Polyethelyne (LPE) dielectric
insulation for reduced static linearization of the laminar air flow
That's true. In this I checked the connections first. All were snug and
clean. I pulled them out and gave them the eraser treatment. Board
still didn't work until I cleaned off the dust from the back side.
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