Check connetions and dust first

[Snuffy "Hub Cap" McKinney]

I finally learned to check these first before jumping into the software or running to the computer store. A good lesson for anyone else interested...

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 again.

Note to self -- try the simple first, dummy.

[Stormin Mormon]

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 .

. .

[bob_villa]

The grease collects dust and a "dielectric" makes it non-conductive! Nice!

[philo]

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.

[Tony Hwang]

Just a common sense.

[J Burns]

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.

[Tony Hwang]

I believe dust creates heat build up causing possible over heating. Excess heat makes things expand. No. 1 enemy for electronics comp[onet is too much heat.

[J Burns]

I don't suppose there's much mass on a USB board. I figured if it was heat, it would have resumed working when he shut the power off long enough to unplug and replace the board a few times.

[Tony Hwang]

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 tech), LOL!

[(PeteCresswell)]

Per Snuffy "Hub Cap" McKinney:

This finally dawned on me when troubleshooting my #1 daughter's PC.

She breeds and raises Bernese Mountain Dogs.... long hair and lots of it.

Moving the PC from the floor to a table seems to have helped significantly, but hair/dust buildup is always the first thing I look for now.

[Scott Lurndal]

USB chips don't dissipate significant heat, even under load. Not like a CPU, which can dissipate upwards of 160 watts or more depending on the clockspeed and SKU.

Where have you been for the last decade? Think 0.8-1.5 volts for most modern chips (particularly CPUs). Takes less energy to switch .8 v than 5.0vdc and you can do it faster.

Ah, that's where.

[Tony Hwang]

Brushed off? Beware of static discharge which can damage something without even knowing it. I always wear anti static strap on my wrist and I'd not brush anything, just vacuum or use compressed air spray can. If board is taken out, I put it on anti static mat which is connected to wrist strap. My old habit.

[Tony Hwang]

[Tony Hwang]

Reduction in voltage comes from mainly much higher density circuit. Every thing is SMALL and CLOSE each other.(Nano tech.) How many x-sistors in a Quad core i7 latest gen. CPU?

[J Burns]

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.

[J Burns]

I've read that where sensitive ICs are produced, tabletops and carpets must be slightly conductive. If a circuit is on the table, a charge could come from friction with the table or friction with moving air.

It takes a special vacuum cleaner because moving air can put a charge on the tip.

I quit using static straps. I figured they weren't foolproof enough for a fool like me. I avoid opening a case if the humidity is below 60%. I lay a cotton cloth on my work surface and spray it enough that it feels damp. The assembly, anything I remove, anything I intend to install, any tools I will use, and an arm or elbow, stay on that damp cloth.

I don't trust moving air. I use a natural-fiber brush. I dampen it first so it's slightly limp.

Kind of like working with black gunpowder.

[bubba]

To all you nitpicking wimps, computers ain't that delicate. Just take them outdoors and blow them out with an air compressor. NEVER had a problem. Sheeeeeeesh!

[Stormin Mormon]

Do you give it a bit of dieelectric grease, like a good Republican, to help keep the contacts clean?

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

Doctor: You have the most advanced case of tennis elbow I've ever seen. Patient: I'm a working man. I have never played a game of tennis in my life! Doctor: What do you do for a living? Patient: I work in a carpet store, demonstrating rug beaters.

[Stormin Mormon]

Did you use anti static air?

- . Christopher A. Young learn more about Jesus .

. .