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Old 02-20-2018, 11:29 PM   #3
coplate
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Posts: 645
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Join Date: Jun 2009
Device: prs-505, Kindle Keyboard 3g, PW3
Quote:
Originally Posted by knc1 View Post
Actually, several of us discussed the use of pogo pins when this connector pin-out was first used on the K4.
(It is the same on all devices since, other than the two Oasis models)

The first speed bump is the pinout spacing.
At a very rough measurement (sighting through a glob of epoxy), those connections are 1.5mm center-to-center.

I.E: that is the maximum diameter a pin can have (when centered over the contact, half of its diameter is towards the other pin - same, same for the other pogo pin and 2 1/2s make a hole whole).

So you go to a catalog, such as:
https://www.digikey.com/en/product-h...oaded-contacts

Find the page on the smallest, needle point, pins:
https://www.digikey.com/product-deta...122-ND/3635123

Then pull up the (metric) data sheet:
https://www.mill-max.com/assets/pdfs/metric/027M.pdf

And find there is one choice:
0985-x-71 ...
Where its largest diameter is less than 1.5mm (it is 1.09mm)
The body diameter (which you need a hole in the back cover to pass it through) is 0.94mm

So all you have to do is drill two 0.94mm holes, 1.5mm center-to-center, to pass the body of the pins.
And without leaving any space for positioning errors, that leaves 1.5 - 0.94 = 0.56mm material between the holes you drill.

You had better be certain your hands are not shaking when you do the drilling of the back cover.

= = = = =

That pin-out pad is a standard size for a connector - some of the K4 devices shipped with the connector mounted.

twobob and I did some research and discover the make and model of the on-board connector socket and its matching connector plug.

I even ordered one or two dozen sets.
The complete set of parts for a connector and its mating plug fit (along with a generous dollop of solder paste) into a small jell capsule. (like a pill capsule).

Dig around here a bit - I posted macro pictures of the parts in one of my serial port hardware threads.
You can get the actually dimensions off of the pictures (just measure directly with gimp or some such graphics program).

- - - - -

Note:
I have not yet successfully placed the connector onto the board -
And I have the proper hot-air, SMD, re-work station and equipment and the electronic microscope to see what I am working on.

Nice idea -
All you have to do is hire some trained fleas to do the work.


I havent seen your pictures of teh connector, I will have to search for those.

This idea came from the pin-through-foam no solder pics that were on the forum, I figure that should work with some kind of pogo pins.


I know I dont have that kind of dexterity.

Maybe the idea of cutting the hole and holding that connector down with some oomph would work, if there was a pigtail coming out to hook your serial board too.
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