Topic: Disassemble a HB unit to make it smaller?

[bigkahuna]

Anyone ever try opening up their HB unit?  I'm wondering if the internal components of a 798 ci hd si might be removed from the original housing and fit into a water tight cylindrical housing with a 4" diameter.  That way I could use the ethernet connection and wouldn't experience signal degradation from extending the transducer cable too far.  Anyone have photos of the insides of a unit?

[Rickard]

Hi,
I have seen some photos from circuit boards here:
http://www.xumba.scholleco.com/viewtopic.php?t=3084&highlight=international
http://www.xumba.scholleco.com/viewtopic.php?t=672&postdays=0&postorder=asc&highlight=international&start=15
The boards look rather big...
Rickard

[bigkahuna]

Darn!  You're right, looks like the board fills almost the entire housing.  I'm sure it's a multi layer board so no chance of cutting it without major issues.  Hmmm... back to the drawing board...

[Humminbird_Greg]

The PCB is about 5 inches X 6.5 inches.
Yep, multilayered: try 8 layers with ground planes on both the primary and secondary sides.  Makes it really tough to solder to especially when combined with the lead-free solder and size of some of those components!

[bigkahuna]

@Greg - Do you happen to know the dimensions of the 898 motherboard?  The 898 is longer and not so wide so that might be a possibility.

[Seems a shame to tear apart a perfect good $1400 unit to put it in a tube.  Maybe I should hang out behind the Humminbird factor and pick up one of their scratch and dent units.    ]

[Humminbird_Greg]

4.25 X 9.5 inches for the main PCB of the 898c Si unit.

When we scratch and dent them they are usually in many pieces bigkahuna.  It’s a great way to relieve work stress!
[Actually we recycle most everything.]

[Rickard]

Some people bake/pot their boards in plastic/epoxi/resin, then there is no need for a waterproof housing.
Rickard

[bigkahuna]

that only protects the board and components, not the wires / circuits that it will be connected to.  If there were an easier way, I'd do it. 

[Rüdiger]

Hi big k

You not only need an ethernet connection but also a power supply.
So I think that the effort with a waterproof housing is not worthwhile, just to make a potentially long cable connection.

mvh
Rüdiger

[Rickard]

These guys use potting instead of housings whenever they can:
http://www.submarineboat.com/waterproofing.htm
 
Rickard

[bigkahuna]

It seems I've hit a topic you fellows have thought about as well...

@Rüdiger - You're assuming my plan is to use this in a towfish, which it is not.  My application will have more than sufficient power for the sonar unit.

@Rickard - Thanks, I've got a fair bit of experience in designing and building submersibles.  There are good applications for potting electronics and then there are situations where it would be of limited benefit, I believe in this instance it is the latter.