standoff problem

aragorn723 · 1735

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Offline aragorn723

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on: January 10, 2016, 03:05:18 PM
Hi,

I built a circuit board for the 3d imaging preamp listed on the board here a while ago, and have a potential issue for mounting it into a chassis.  The board is perf board, and two of the traces come very close to the mounting holes (they are both signal paths).  The board will go into my old Quickie chassis, which now has a 6 X 10 aluminum plate on top.  Originally, I wanted to mount the board to the plate (underneath) and also the RCAs, but since these 2 traces are so close to the mounting holes, they will probably touch the standoff, and potentially short to ground.  I might be able to bend them a little bit and use an insulated standoff, but was wondering what other options there are (maybe somehow mounting the board to the inside of the wood for the chassis?  Any ideas?  Thanks,

Dave


Offline Paul Birkeland

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Reply #1 on: January 10, 2016, 03:11:44 PM
Use a nylon standoff and a plastic screw.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline aragorn723

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Reply #2 on: January 10, 2016, 04:56:58 PM
A 4-40 nylon screw looks like it might work ( gotta pull out a metal one to check), but the nylon but is 1/4" ( from home depot).  This is probably going to be a game of millimeters to see if it fits!  Gonna give that a try, but if not, that might mean desoldering the resistor in qustion, and relocating to another spot on the board.  Will let you know how it goes!

Thanks, Dave


Offline mcandmar

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Reply #3 on: January 10, 2016, 11:17:40 PM
Probably not much use to you now due to shipping times, but you can buy kits of nylon standoffs from eBay for very little, worth keeping a few in stock.

http://www.ebay.com/itm/131610830796

M.McCandless

Offline aragorn723

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Reply #4 on: January 11, 2016, 12:18:12 AM
That's good to know!  I still have to set up my drill press and get a bunch of holes drilled (first time ever).  Gonna check out evay tonight!

Dave


Offline aragorn723

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Reply #5 on: January 17, 2016, 11:04:35 AM
What is the metric equivalent of a 4-40 screw?

Thanks,

Dave


Offline Paul Birkeland

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Reply #6 on: January 17, 2016, 11:11:01 AM
Quote from: aragorn723 on January 17, 2016, 11:04:35 AM
What is the metric equivalent of a 4-40 screw?
This is a question that has no answer.

A 4-40 screw has a shank diameter and thread pitch that do not match any metric screws. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline mcandmar

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Reply #7 on: January 17, 2016, 11:47:05 AM
The closest in size visually is an M3 x 0.5mm thread, but as above they wont screw into each other.

M.McCandless

Offline rif

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Reply #8 on: January 17, 2016, 05:28:48 PM
Amazon has standoff kits some with one day delivery.

-david

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