Screwball sleep issue - moving chair wakes PC with no physical contact

dalchina said:

I suggest it's a standing wave- solution- when you get up, slowly of course, stand, then wave.

I know those Wave brothers and Standing was the worst of the lot...

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Thank you dalchina,,,believe it or not your joke actually triggered a memory which I just used to pinpoint the root cause of this - I'll call it phenomena.

Back in 1961-1963 I was working for Philco Techrep on the NASA S55C Micrometeoroid Detection Satellite project. Philco was responsible for the design, fabrication, and testing of the flight article. It's job was to determine if the environment in which future manned orbital missions would be operating might be hazardous and if it was, how much so.

Nobody knew anything about that environment in those days in terms of human/mission safety. S55C was designed be able to not only quantify micrometeoroid density but more importantly the energy an impact might impart to an orbiting spacecraft. Of course no sensors existed at that time that could perform these measurements so a major effort was made to develop sensors that could perform this task.

Three types of sensors were ultimately developed, calibrated, flight qualified, and mounted on the entire external skin of the satellite for maximum exposure. My specific job was to fabricate/qualify the encoder that connected each sensor's data output to the telemetry downlink and then integrate all of the modules into the innards of the S55C.

In order to meet the power budget requirements transistors had to be used to fabricate the necessary electronics but there was very little experience with transistors to draw on at that time so we were learning as we went. The transistors chosen for the encoder were of the point contact design which were great amplifiers but fairly sensitive to an overvoltage condition.

But, I ramble...

All of the components were mounted on custom made printed circuit boards and encapsulated in a dielectric foam to control vibration effects. The modules were then tested to verify proper function before integrating the flight data package.

Horror of horrors...about 20% of the point contact transistor circuits had failed during the encapsulation process. I had to identify each failed transistor's location, remove the foam around it, remove the transistor, solder in a new transistor, and patch the removed foam. Retesting revealed that some of the replaced transistors had also failed during the patching. This process continued until testing proved that we had a functioning module with no failed transistors.

I said all that to say this: Obviously a whole lot of investigation and testing went on during this time. After all, this thing was going into orbit and we need to be as sure as we could be that no more failures would occur in orbit. We had to figure out the failure mechanism. Thus the reason for bringing this up.

I discovered static electricity can "flow"...I always thought STATIC electricity was, well, STATIC. The potting compound was a liquid that would morph into foam. The modules would be placed in machined pressure vessels and potting compound introduced into the vessel and capped off. the liquid would expand into all of the voids forming a robust "container" for the module. Bottom line is that encapsulation in this manner created a retained static voltage gradient across any two points on the module which took a long time to bleed off.. the encapsulation what generating enough current to destroy that sensitive point contact junction,

So, I noticed this morning before I woke the system up that I could move the chair all around before I had sat in it and the PC stayed asleep. I then sat in the chair a while and repeated the process and the PC did wake up when the chair was moved.

So, to prove the point I took a hair spray bottle and filled it with water. This provided a very fine mist which I sprayed around on the carpet and chair and even sprayed a little on my butt and shoes.

Repeated tests show that whatever was causing the moving chair to wake up the PC was neutralized by misting with water.

OK - - -

If I move the chair BEFORE I sit in it a while the PC does NOT wake up until the mist has dried up.
If I move the chair AFTER I sit in it a while the PC DOES wake up.
If I move the chair after I mist the chair and area the PC NEVER wakes up

That's my story and I'm sticking to it.

Thanks again for triggering this memory...

What's the covering of the chair made of?

clam1952 said:

What's the covering of the chair made of?

I don't really know, it's tightly woven, probably synthetic and is whatever Steelcase uses on their Leap ergo office chairs.

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dalchina said:

Great story - wow- point contact transistors... I can admit to having experience with (thermionic) valves.
I recall one day someone carrying a PCB into the lab, then someone else pointing at something on the PCB. A spark flew. Just your basic static- nothing interesting.

Question might be asked- why is your encased PC vulnerable to static. And as you know, static can be significant without having visible effect.

Yes, that came to mind as I was re-running that memory. The PC is in a 24 inch high Coolermaster HAF-X case, the internal cage being made entirely of steel except for a plexiglass making up about 25% of one of the side panels. The internal hot-swap and SSD drive cage is steel and the way it's put together pretty much shields the internal components. However, underneath the table is a real rat's nest of network and power cables all acting like antennas

Cable Management - I don't need no steenkin cable management!

sygnus21 said:

Thank you. That clarifies a lot. And yeah, I have to believe it's something else (perhaps vibration) because simply moving a chair that's not electrically connected the PC in any way (I assume?) makes no sense.

I know if I bump my work station desk the PC will wake from sleep, but my mouse and keyboard also sits on that desk.

It's most likely just sensitive to the vibrations you're causing by moving your chair.

My PC will awaken whenever I open or close one of the drawers in the desk it's sitting on.

And there was a time when my noisy neighbors downstairs had a wild party. Just the vibrations from their loud stereo rock music coming through my floor woke up the PC.

If the surface that the PC is sitting on is just tilted a degree or two (floors aren't perfectly level), then vibration may cause the mouse to slide just enough to wake the PC.

dalchina said:

- except this happens with no mouse connected as per 1st post I think.

Yes, that's correct. By now, if one has read the entire thread (without skimming), one will see that I have completely exonerated the PC from any fault in this phenomena which is why I came here in the first place - to get some peace of mind that a potentially fatal failure mode was developing in the PC.

I am no longer concerned that there is anything wrong with the PC. I have been cautious to a fault the keep the PC physically and electrically out of the equation during the last 2-3 days in investigating the phenomena. In fact, the first thing I did when I crawled out of bed this morning was to check to see if the PC was still asleep. It was, so after a night of me not having sat in the chair I was able to move and roll it around near the PC to verify that the PC would not wake up by this activity.- I had to press a key to wake it up. After an hour or two I will rerun the test and I am certain that chair movement will do whatever it does and again wake the PC from sleep.

I no longer feel like a bag of rocks hanging by a frayed rope over my head.

But, I do feel pressure to keep at it and drive whatever is causing this to ground - literally.

xwray said:

I don't really know, it's tightly woven, probably synthetic and is whatever Steelcase uses on their Leap ergo office chairs.

Was thinking of known materials that can build up a static charge such as nylon, polyester and probably a few other synthetic materials.