T&T: nav computer failure

[Chester Brummett]

Conformal coat can still be applied to a circuit board with plugs, switches, 
jumpers, etc.  Masking is required before the application of the coating to 
make sure that the conformal coat does not get into these contacts.

One step, part of the complexity of doing conformal coat correctly: an 
expensive, involved process.

When we did board for military programs that had a contract requirement for 
conformal coat, the process had to be developed for each board type.  the 
reason a function called manufacturing engineering exist, these engineers 
develop the detail processes.

Don't think any of the  "marinized" computers go to these steps.

Available if you want to pay big bucks for military or industrial harsh 
environment embedded computers.

But I don't think that later route would be cost effective.  Pay big bucks 
for a nav computer that would last for 10+ years?  As you pointed out, 
technology advances.  I recently upgraded CE from 1.1 to 2.0.  Did not 
require a replacement of the computer to do this, though.

I guess my concern boils down to:  I want the nav system to be reliable for 
whatever life I plan/expect to get from it.  Don't like to be in the middle 
of a three month cruise and have the navigation system fail.

Does this mean that I should just replace every three years reguardless? If 
the environment (Humidity and salt air) is the cause of the failure (I 
suspect, but cannot prove), Can I rely on the computer for 3 years? Or 4 
years?  I am not sure there is an answer to this question.

I think the only present answer is to replace the failed unit.  I like the 
computers marketed by Island Time PC.  Built-in dual monitor drive 
capability, and a power supply that will run from raw 12 VDC.  Much lower 
power drain than present unit.  And the form factor will fit the limited 
space available (no room for a standard short tower or desk top chassis).

And I recently purchased a WiFi bridge/transceiver/antenna system from 
Island Time PC and was impressed with their service and tech support.

Chet

Arild replied:


> REPLY
> Conformal coating  is not effective when  plug in sockets are part of the 
> assembly.
> And as Eric  T  stated, conformal coatings can inhibit  heat dissipation.
> Spraying  with  Corrosion Block  is a two edged sword since it does create 
> a dust magnet  when cooling air is blown through the insides of the 
> computer. Unless you modify the whole thing with HEPA filters and change 
> them religiously, it probably isn't worth it.
> Corrosion block does provide corrosion protection by  coating contacts 
> with an air excluding film except wher actual contact is created by 
> presure of th efinger springs.  In that sense it is effective.
> It also provides protection  whereas  conformal coatings  may  create a 
> dielectric barrier in sockets.
> Been through that as a QA Manager on a government contract job.
>
> Given the cost to  'marinize'  any computer it is usually not cost 
> effective, unless you do it yourself.
> Extra cable ties and hot melt glue on connectors like fan power connectors 
> may be in order.  they main connectors are either provided with a lock 
> clip or a very tight friction fit. Adding even more may make the whole 
> assembly unserviceable in the event of actual component failure.
>
> If you spend $1200  for a computer that last 4 years, the cost is $25 per 
> month or less than a dollar a day.  Not too bad as an operating expense. 
> If you can salvage somethggn from the computer after 4 years,  its a 
> bonus. Given the rate of technical progress and innovation,   A 4 year old 
> computer is past its prime.
> For that matter, how many people now run dedicated electronic navigation 
> gear for longer than  4 years without  wanting to upgrade it somehow.  How 
> much of the dedicated stuff last well past 4 years without so much as 
> needing a cleanup?  Several list members have  asked how to rejuvenate 
> LCD displays  that seem to have faded after a few years in service.
>
> Arild