Comment on 'boardswapping' as part of the computer culture.
jim at g1jbg.co.uk
Fri Oct 28 05:06:43 CDT 2005
I'll wade in with my comments now.......
Board swapping is a useful method for high reliability systems (I work in
air traffic control engineering), and leads to a very high availability of
the system, especially when coupled with high levels of redundancy, we use
the "three level" service/maintenance regime that has already been
However, for the system to provide the required levels of service, it needs
a serious investment in spares, logistics and training, for example:
Spares. All spare boards in the system must be tracked to a known state of
serviceability and modification - as Tony has pointed out, just because it
says the same thing on the box, it isn't always the same!
Logistics. You need to have the right parts in the right place at the right
time - because of the different skills required for 1st, 2nd and 3rd level
repair, at least the 3rd level, and often second level workshops are of
site. You need a good stores and transport system to move the stuff around
fast, and to track where it is (a computer is NOT always the answer....).
You also need an organisation to keep the repair centres fed with the
correct spare components, and to provide a "lifetime buy" service for
components which are about to become obsolete (I know of some systems that
are nearly 40 years old, and are kept at extremely high levels of service
with this kind of service).
Training. Even the first line technicians need a high level of training, you
have to be able to interpret the fault symptoms and work out which board to
change. I have some system training so ingrained that I can diagnose faults
over the phone 10 years after I last worked "hands on" on the equipment.
Now back to our systems! With the above in mind:
1. we rarely know the state of any parts we have - a board that has been
un-used for 20 years is quite likely to be faulty!
2. We are self trained on these systems. If we can narrow a fault down to a
board, we can often take it down to the component.
3. We are lucky to have any spares!
Looking at a less than vintage system, for the most part, it is difficult if
not impossible to go below board level ( I can sympathise with Tony here),
and nigh on impossible to get information on how that board is working, or
even get test equipment that can capture the signals involved (I have a
100MHz (valve) scope with a 4 trace plug-in, or I can borrow a very old
logic analyser from work). At this point, we are reduced to board swapping
as the only option, though often with little measurement to back it up - the
only thing we have over the teenager in PC World, is that at least we have a
multimeter and can check the power supply voltages........
We are also at the point where PC components are so cheap they are not worth
repairing - I can buy a LAN card for less than £10. It costs me more than
that to pay an engineer to replace it, let alone try and repair it. Even the
kid in PC world expects £5 an hour - if you try and charge some one £50 for
changing a LAN card, you'll soon be out of business
I'll duck know.
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