[mythtv-users] FE/BE combo system locking-up

[Stephen Worthington]

On Wed, 15 Dec 2021 12:30:43 -0700, you wrote:

>On 12/14/21 1:34 AM, Stephen Worthington wrote:
>> 
>> This one - dust certainly can cause this, and if you are not at least
>> annually getting rid of it, it will cause problems.
>> 
>
>I planned to d some system maintenance today, so I ran top before I 
>shutdown the system, the top process is mythfrontend:
>
>
>     PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ 
>  COMMAND
>     857 mythtv    20   0   10.4g   1.5g  40620 S   2.3  40.3  99:47.74 
>mythfro+
>
>Out of curiosity, I restarted the frontend:
>
>     PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ 
>COMMAND
>   31446 mythtv    20   0 9909088 791048 126944 S   1.3  19.7   0:06.45 
>mythfro+
>
>Still seems like a lot of RAM, but it's much better than before.
>
>I had vacuumed the system in July, but I vacuumed it again. I also 
>borrowed the power supply "tester" from work, voltage levels and PG 
>signal passed.
>
>FYI - my problems seemed to start when I changed to Debian 10 back in 
>July, around the same time I vacuumed the system.
>
>Bob

"Vacuumed" - do you really use an ordinary household vacuum for
cleaning electronics?  That is a really bad idea!  Most vacuums create
huge static electrical charges - they are actively dangerous to
electronics.  There are special non-static electronics safe vacuums
that you can buy, usually from commercial electronic component
suppliers.  But they are massively expensive.

The normal way to clean electronics is to blow out the dust using a
spray can of compressed gas or compressed air designed to be static
safe.  Most hardware stores will have at least one brand of this.  You
usually find it with the other workshop aerosol products, like CRC for
engines.  Computer shops will often also stock it.  It is
unfortunately not particularly cheap.  Here are some from NZ shops:

https://www.pbtech.co.nz/product/CLECXT1298/Cruxtec-CL-1827F-Clean-Range-compressed-Air-Duster
https://www.pbtech.co.nz/product/TOLSTO1040/Dynamix-CK-AD400-400ml-Air-Duster-Non-Flammable-hi
https://www.bunnings.co.nz/wd-40-350gm-specialist-air-duster_p0241477

When using your compressed gas spray, you should be grounded to the PC
chassis or power supply using an anti-static wrist strap:

https://www.pbtech.co.nz/product/SEVOEM0064/Posh-TA-001-Anti-Static--ESD-Wrist-Strap--Wristban

I am afraid that it is not unlikely that your vacuuming efforts will
have been the cause of your problems.  The closer the vacuum nozzle
came to a chip, the more likely it was to have damaged it, as the
vacuum nozzle will have had a very high voltage on it.  The voltage
differential to the silicon in the chip causes movement of atoms and
molecules and changes the characteristics of the junctions in the
chip.  Immediate failure can result, but it is more normal to get
degradation that fails later in life.  And if the nozzle came close
enough so there was an actual static discharge, even more damage is
likely.