How to mod beamspring connectors for tightness

pandrew

12 Sep 2020, 21:56

The blue modern 3.96mm card edge connectors that are often found on ebay/aliexpress, and are used for converting Beamspring keyboards are often a lot looser when compared to the original connector.
They are often so loose that some columns/rows don't make proper contact, and even vibrations can knock a row/column always-pressed/always-unpressed.

If you already have a converter built and soldered, then your best option to mitigate this is to add a piece of paper, to increase tightness. Keep in mind that if looking at the keyboard and connector as if you were typing on it, column contacts are on the bottom left, and row contacts are on top right. So I recommend adding a piece of paper on the top-left, where there are no contacts that are really in use. If the tightness problem is really severe, you may experiment with increasing paper thickness, or using multiple sheets of paper, and you can also try adding a piece of paper on the bottom-right, underneath the rows. (Original idea by kmnov2017).

This guide is a much better solution, but it only applies to you if you still have a pristine unsoldered connector, that you can mod to be tighter. If you follow these steps, the connector will be around as tight as the original connectors, and you will need to use more force to connect/disconnect the converter to/from the sense pcb.

Step 1 - remove the pins

Remove the pins, by grabbing the part that is solderable, and pushing them straight through with pliers.
The pins are very easy to bend, so be very careful.
Try to grab a good surface area when pushing, and always push in the direction that is perfectly parallel with the pin metal.
01_push_pins_through.jpg
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If something like the following picture happens, it's best not to attempt fixing this pin by bending it back. just break it off, and using a needle push it so the other end falls out of the connector. This is a good reason why to get pins that are bigger then 2x30 pins, because you have extra pins in case you break some. (Also right now 2x30 pin variants don't seem to be available anyway)

(If you don't have any extra pins, then really-really pay attention to make sure something like this doesn't happen, and I guess if it does, try to save it, but set it aside, and only use it for contacts that don't carry any signals.)
02_if_something_like_this_happens_do_not_try_to_save_the_pin.jpg
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I recommend pushing out all pins at once, rather then modding pin-by-pin. This allows you to be faster. So after you pushed out all pins, you have an empty plastic connector, and a pile of pins:
03_until_you_get_a_pile_of_pins.jpg
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Step 1b - Perform any cuts
All the cuts that need to happen to the plastic are best done at this point, in order to avoid damage to the pins.
Examples are:
* If bought 72-pin connectors, cut off the excess pins
* If building a compact beamspring connector, the extra plastic on the left side should be cut off, because the pro micro will not leave space for it.
* If the controller can be used for 327x/3101 keyboards, then the sense PCB can be assymetric so a slot should be cut in the right end of the connector. See this post for more details. viewtopic.php?p=473635#p473635

Step 2 - First Bend

This is what a single pin looks like:
04_this_is_what_a single_pin_looks_like.jpg
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Bend the contact part of the pin upwards by 15-20 degrees: (does not have to be very perfect)
05_bend_the_contact up_around_15_20_degrees.jpg
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Because of the little guide-holes in the connector plastic this bend is not sufficient. The little guide holes would bend the pin back into its original shape, if you inserted it like this into the connector:
06_the_first_bend_is_not_enough_because_the_little_holes_in_the_plastic_force_the_pin_back_in_its_original_shape.jpg
06_the_first_bend_is_not_enough_because_the_little_holes_in_the_plastic_force_the_pin_back_in_its_original_shape.jpg (1.08 MiB) Viewed 726 times
Step 3 - Second Bend

So you need to add another bend in the middle of the contact part of the pin. Try to make it so the two marked blue lines are roughly parallel. But again perfection is not necessary: Angles are not so important to be perfect, but try to make so that the position of the second bend is consistent across pins, for aesthetics. This will still work even if the position of the second bend is inconsistent.
07_add_another_bend_in_the_middle_of_the_contact.jpg
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To make the second bend, I held the pins with tweezers, and I applied pushing force where shown by red arrows:
08_how_to_add_bend_with_tweezers.jpg
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After I took the picture I realized that I have stronger tweezers the tips of which are made out of ceramic, so I did all the remaining pins with the ceramic tweezers. My needle nose pliers were too thick for this, but if you have very thin needle nose pliers, I recommend using those instead.
09_i_used_ceramic_tweezers.jpg
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Step 4 - Gently push the pins partway back

Push the pins back into the connector until part of the pin goes through the hole on the back of the connector.
Do not apply force on the contact side of the pin to make the pin snap back into place.
This step only places the pin back halfway:
10_gently_push_the_pins_back_in_place.jpg
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Step 5 - Pull the pins from the other side, with pliers, until they click
11_pull_the_pins_until_they_click.jpg
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Step 6 - Solder the connector to your controller

Do not try to put the connector on the beamspring after modding the connector without having it soldered to a controller.
The modded connectors are much-much tighter, and require force both to put the connector on, and take it off.
You risk bending the pins, and also you risk some of the pins popping off while you take it out.
Soldering it increases its mechanical stability. Solder it first, and only then try it!

Results
Here you can see a non-modded connector on the left, and a modded connector on the right.
You can see how much gap there is between the pins on the unmodded connector:
12_comparing_modded_and_nonmodded.jpg
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Here you can see the side view of the pin shape after modding:
13_modded_pins_in_connector_side_view.jpg
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I was very disappointed with the reliability of the non-modded connectors, but I have done this mod on 9 connectors so far, with 100% success, and they are 100% reliable now!
Last edited by pandrew on 02 Nov 2020, 02:32, edited 9 times in total.

kmnov2017

12 Sep 2020, 21:57

Great job Andrei, I am going to do that on my beamspring

User avatar
SneakyRobb
THINK

12 Sep 2020, 22:02

Hi,

I think this is a good idea. Very often the connectors you get are very loose. Not sure why it is, but they often fall off. This is a quick easy way to fix. Good job thanks.

pandrew

08 Oct 2020, 00:13

Hey guys,

So I just received a batch of new 2x36pin card edge connectors I have ordered from aliexpress, from this listing:
https://www.aliexpress.com/item/3301574 ... 4c4dMsOo6X

I received a mix of "light blue" and "dark blue" connectors:
comparing_connectors.jpg
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These are fairly different connectors: The plastic is made out of different mold, the pins have a different shape, and are made out of different materials.
Let's compare the pins:
comparing_pins.jpg
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The top ones are from light-blue connectors (modded by me, I took the pictures after I didn't have anymore unmodded pins)
The bottom ones are from non-modded dark-blue connectors.
The quality of the dark-blue pins is much lower:
* the dark-blue pins are much easier to bend, and are not very elastic/springy. I think these connectors will survive fewer insertion cycles.
* the dark-blue pins are only plated (with wathever material) on the tips that are visible from the outside. This is useless, those parts of the pin don't even make contact most of the time. This is all just for show, so they look better.
* the dark-blue pins have a single pair of stabilizing wings that go into the plastic. This makes them slightly harder to insert back into the connector after removing them.

Now to compare the non-modded pin distance between the connectors (this is not one picture, I photoshopped together two pictures.) Left is light-blue non-modded connector. Right is dark-blue non-modded connector:
compare_light_blue_with_dark_blue_pin_distance.jpg
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Based on the above picture I think the non-modded dark-blue connector will perform initially somewhat better then the non-modded light-blue connector. However I still think it's not so great to use these unmodded.

The non-modded dark-blue connectors don't feel any tighter then the non-modded light-blue connectors.
And take a look at a picture of the 5251 card edge:
20201008_001632-0.jpg
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The pads don't reach the edge of the pcb.
I think sometimes something like this happens: (red is connector pin, black is PCB, green is the contact pad on PCB)
contact_sketch.png
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So I think the pin shape itself is sometimes preventing a good contact. I think this is true for both light-blue and dark-blue connectors.

When modding the dark-blue connector, try your best to avoid this situation:
try_to_avoid_this_with_dark_blue.jpg
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You can avoid this by being careful when you bend the pins, to only bend the pin on one axis, and carefully lining up the pins that face each-other, before pulling the pins back into the connector.

So as a conclusion I recommend getting light blue connectors, and modding them. If you really don't want to mod them and take your chances without modding, then I recommend getting the dark-blue connectors.

When it comes to sellers, the aliexpress seller I linked above advertises pictures of the dark blue connectors, but sends you a mix of dark/light connectors. It doesn't mean don't buy from this seller, but I recommend contacting this seller and telling them about your preference.

The other place I got connectors from is this ebay listing:
https://www.ebay.co.uk/itm/Connecteurs- ... 2749.l2649
This listing advertises light blue connectors and also delivered to me only light blue connectors.

Another thing I wanted to mention that I switched the tool I use to do the bending of the pins, from ceramic tweezers to very small needle nose pliers:
small_needle_nose_pliers_pro_micro_and_card_edge_conn_pin.jpg
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These make it alot easier, but it still takes a long time (it took me an entire day to mod 18 connectors)

pandrew

08 Oct 2020, 00:24

TLDR:
tldr.png
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pandrew

18 Oct 2020, 17:13

Two small updates:

1) The light-blue pins have little metal tabs cut out to bite into the plastic and hold the pin in place,
I have exaggerated its size in this diagram:
little_biting_tab.png
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When you press the pins through from the back, make sure to never twist like this:
little_biting_tab_dont_twist_like_this.png
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This kind of twisting will encourage the tab to bite more into the plastic, and will prevent you from cleanly pushing through the pin.
Always apply a force that is parallel to the pin direction (to the right here), or if anything, twist it a tiny-tiny bit in the opposite direction.

2) I found these interesting black connectors:
black_connectors.png
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Aliexpress link:
https://www.aliexpress.com/item/4001280 ... 4c4dMMESqF

These connectors are taller, and according to the diagrams they may have a better pin shape, so these might not require any modding.

See the better pin shape here:
black_connectors_may_have_a_better_pin_shape.png
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I ordered a couple just so I can test them out.
Not sure how compatible their shape is to existing controllers.

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