Re: [PLUG] More hardware woes

[Steve Litt via plug <plug@lists.phillylinux.org>]

Walt Mankowski via plug said on Wed, 16 Nov 2022 21:31:09 -0500

>My previous thread was getting long so I'm starting a new one. Quick
>summary -- while attempting to swap drives in a RAID1 array, my
>desktop box got into a state where the power would shut off while
>booting up.

[snip]

>I brought it home and sure enough it booted up without any problem!
>Woot! I removed the faulty drive from the RAID array, shut the box
>down, and swapped out the old drive for a new one.
>
>Then turned it back on. It got halfway through booting up and the
>power shut off. I checked all the connections and tried again. Same
>thing. I physically disconnected the power and ribbon cables from the
>new drive. It probably shut off even faster this time.

Intermittents suck. They're difficult to diagnose, and they're a huge
time sink. Given my rather unique profession, I've written a lot about
intermittents, some of which I'll list at the bottom of my post.

You've had many good suggestions. I'll present a couple more.

First, I had symptoms quite like yours in a whole fleet of computers,
which, interestingly, had the same model case. It turned out that the
root cause was the power and reboot switches. So what I did was 1)
removed the reboot switch, which is a relic of the 1980's, along with
the reboot switch's wiring, and 2) replaced the power switch with a two
dollar, wholly mechanical, no light, no battery, no electronics
doorbell switch. Doorbell switches have much less "bounce" than case
switchs, and doorbell switches have a normally open gap over 1/8, so
there's no possibility of them being resistive instead of either fully
closed and fully open. 

Replacement with doorbell switch takes only minutes, and might be
doable removing only the front panel. You cut and strip the old
switch's wires at the old switch, then you connect those wires to the
wires that come with the doorbell switch, and then you glue or
otherwise attach the doorbell switch to the front panel. Soldering and
shrink wrap or electrical tape is ideal, but even a twisted connection
secured with electrical tape should work just fine if you strip about
3/4 inch off all the wires and wind them tightly. 

Here's a documents showcasing a symptom much like yours, how much
trouble I had diagnosing it, and how I finally fixed it:

http://troubleshooters.com/tpromag/200807/200807.htm

Another very common cause of intermittence is fretting corrosion (link
to fretting corrosion document later). Fretting corrosion is eliminated
or hugely reduced by lubricating all low voltage electronic contacts.
I've used many types of lubricants in the past and most are hard to find
today. 

These days I lubricate electronic contacts with Super Slick Slick Stuff:

https://www.idealtruevalue.com/store/p/152696-11-OZ-Super-Slick-Slick-Stuff-Lubricant-Is-A-Non-Petroleum-Base-Cleane.html

Whatever lubricant you use, use it sparingly and try to keep it off
plastic, because most of them aren't specified as not being harmful to
plastic. For daughter cards, I apply a little bit and then rub it in
with my fingers.

In the past I've also used Breakfree CLP gun lubricant, transmission
fluid, and several of the lubricants listed in the URL at the bottom of
my post. I've even used WD-40 in a pinch, although I don't recommend
it due to its wax content. The important thing is that it's a lubricant
so that it not only cleans the contacts, but leaves a lubricant to
prevent or retard future fretting corrosion.

I lubricate every external USB connection, Ethernet connection, and
video connection. Internally, whenever I disconnect a cable I lubricate
its contacts. I lubricate the contacts on all daughtercards and RAM
sticks. Yes, this is a lot of work: About two hours worth on a desktop
computer. But I hate intermittents so much that I'm willing to do this
work. I've had intermittents last for days.

There's an art to lubricating electronic contacts. After lubrication,
you need to connect and disconnect about 20 times to break off any
existing corrosion. After that, the connection should be good for
several years.

I also lubricate the contacts of batteries before putting them in a
flashlight or other device. This greatly reduces the "blinkies" on
modern LED flashlights, by keeping the battery contact resistance very
low. On those rare flashlights that still have the sliding metal
switches, I lubricate the sliding metal too.

One other thing: Your idea of buying a new computer might be a good
one, as long as you use ABSOLUTELY no components, including the case,
from the old computer, in the new one. Getting back to business is
priority 1, you can fix your current computer later and use it for a
spare.

Here are a couple URLs for you:

Short document about fretting corrosion:
https://materion.com/-/media/files/alloy/newsletters/technical-tidbits/issue-no-33---fretting-corrosion.pdf


Document about lubricating electronic contacts: 
http://troubleshooters.com/tpromag/200310/200310.htm

HTH,

SteveT

Steve Litt 
Autumn 2022 featured book: Thriving in Tough Times
http://www.troubleshooters.com/bookstore/thrive.htm
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