K
Ken Taylor
Guest
"Roy J. Tellason" <rtellason@DONTSPAM MEblazenet.net> wrote in message
news:vqlb5ciq6bvqb9@corp.supernews.com...
earthed from one to the next, so replaced that with earthing going back to a
common power earth at the supply entry. Did the same with the comm's into
the box - any earths from outside the equipment were isolated from the
chassis and only bound to the chassis at *one* point. This was for all the
coaxes and also the RS-232 cables. The power earth was tied to the same
point, and we deliberately didn't use one of those IEC connectors with the
in-built RFI filtering - we replaced that with an in-line version that we
had a bit more control over, earth-wise. Problem went away after all this,
but we should have designed it all in from the start - it's a lot easier
than a redesign! We just didn't realise the magnitude of the problem until
we started putting kit out into the field..
Cheers.
Ken
news:vqlb5ciq6bvqb9@corp.supernews.com...
actually at half-supply (found that one when it bit me!). The frames wereKen Taylor wrote:
I had a similar problem with 1488/89's in equipment at an air force
base,
continually losing them to lightning and surges. Right up until I
cleaned up
the building earthing and tidied the equipment's comm's wiring (again,
particularly the earths).........
Ken
I used to get these terminals in all the time, with exactly that problem
and
for exactly that reason. Thse chips weren't socketed in the original
manufacture, but I installed sockets to make replacement easier on
subsequent visits.
I never did get out to the site, but know that it involved a cable run
from
one building to another at a local small airport.
Care to elaborate on what you did to fix the problem?
Had two problems - one rack was missing it's frame earth, so the frame was
earthed from one to the next, so replaced that with earthing going back to a
common power earth at the supply entry. Did the same with the comm's into
the box - any earths from outside the equipment were isolated from the
chassis and only bound to the chassis at *one* point. This was for all the
coaxes and also the RS-232 cables. The power earth was tied to the same
point, and we deliberately didn't use one of those IEC connectors with the
in-built RFI filtering - we replaced that with an in-line version that we
had a bit more control over, earth-wise. Problem went away after all this,
but we should have designed it all in from the start - it's a lot easier
than a redesign! We just didn't realise the magnitude of the problem until
we started putting kit out into the field..
Cheers.
Ken