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  #11  
Old 03-10-2017, 02:27 PM
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AllThumbs AllThumbs is offline
 
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Seems like you need a gratuitous red, white, and blue wire attached to the box so, during a pre-flight with a new passenger, you can suddenly yell "Oh, no, the self destruct mechanism has activated! Quick, hand me those side-cutters... was it the red wire or the blue wire???? I've got to think quickly!!!!"
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  #12  
Old 03-20-2017, 04:02 PM
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As it's cheap and surface mount (not easily repairable part) I would just rtv it in place. I would use five blobs one in the center of the board for board flex. Don't scrimp on the blobs. We use that method in production all the time, works.

Bob burns
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  #13  
Old 03-20-2017, 04:26 PM
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The package labels are not much help in picking out an acid free silicone, but there are rubber adhesive products which seem to be solvent based. So, it's now fastened into place with four dots of...well, Goop:

http://eclecticproducts.com/products...l-purpose.html
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  #14  
Old 03-20-2017, 04:37 PM
David Paule David Paule is offline
 
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It would be good practice to put some type of support under that big round thing and another under the large IC. The idea is to help prevent board flexing, which over time causes fatigue of the connections into the board.

Believe it or not, there's a whole book on the topic for engineers, "Vibration Analysis For Electronic Equipment," by Dave S. Steinberg. It's actually one of the better books about vibration analysis generally, and is oriented to the working engineer.

Dave
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  #15  
Old 03-20-2017, 05:15 PM
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Why the box? The few "non-serviceable" circuit boards I have are mounted behind the panel, with nylon standoffs to structure, in a vertical orientation.
Knowing you from your posts, I am sure there is a good reason.
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  #16  
Old 03-20-2017, 05:51 PM
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Quote:
Originally Posted by JonJay View Post
Why the box? The few "non-serviceable" circuit boards I have are mounted behind the panel, with nylon standoffs to structure, in a vertical orientation.
Knowing you from your posts, I am sure there is a good reason.
At two bucks for a box, it seemed like a sensible thing to do. Easy to mount a box in a convenient spot, and the board is protected.
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  #17  
Old 03-20-2017, 06:12 PM
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Quote:
Originally Posted by DanH View Post
At two bucks for a box, it seemed like a sensible thing to do. Easy to mount a box in a convenient spot, and the board is protected.
That's half a pint of beer!
Yes, I neglected to notice you have to get to this at least once to set it up. My boards are all dumb and tucked away only needing access if they fail.
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  #18  
Old 03-20-2017, 06:18 PM
rv7charlie rv7charlie is offline
 
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'Acid free' silicone sealant/adhesive is typically marked 'sensor safe'.

Machining off the existing hard points might work fine, but typically they're there to add strength at the mount points.

If you mount to a clean surface with that Goop, or other products using similar formulations (Shoo Goo, etc) you'll almost certainly break either the board or the box before the adhesive releases. I'm aware of some fairly heavy components that have been mounted on the hot side of firewalls using similar products (no hardware) that have remained in place for decade(s).

Charlie
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  #19  
Old 03-26-2017, 10:14 AM
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i hate to mention the favorite goop of airplane builders but proseal works great for that purpose also.

bob burns
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  #20  
Old 03-26-2017, 11:11 AM
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Snowflake Snowflake is offline
 
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I know it's already mounted now, but here's another thought for the next person:

Use a dremel to remove the existing standoffs, and rough up a flat space on the inside of the case in a pattern that matches the mounting holes on the PCB. Then mount 1/4" threaded standoffs to the board with matching screws that won't go all the way to the bottom of the standoff. Put epoxy on the bottom of the standoffs, and press the assembly into the case. Allow epoxy to harden.

Now you can remove the screws to remove/service/replace the board, and your standoffs will remain for the next install. Obviously, don't torque too hard on the screws when installing, even epoxy has limits.
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