A way to restore Futaba MA?

User avatar
browncow

05 Nov 2022, 09:54

After a painfult desoldering process with a lot of pin un-bending i have disassembled my chicony 5181 with futaba MAs.
The board was pretty nasty with a lot of dirt in it, and half the switches click weak or not at all. So i've decided on a full stripdown, and then replacing the switches with ones from a donor board that didn't power on, but had pretty much brand new switches.
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After i had all the switches free from the board though, i started thinking why is it that some have stopped clicking. The switch mechanism itself is rather interesting to me and i really like those, so i thought why not to open some up, as there is nothing to loose now since they're in such a bad condition.
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First, cut four melted plastic tops of the pegs that hold the housing together like this.
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Then, find a place where the housing comes together from two parts. gently stick a knife in there and pry both sides a little. After that you should be able to just slowly pull the bottom of the housing out. Do not press the slider, or the switch will literally EXPLODE onto you. :lol:
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After examining clicking and not-so-clicking switches, i noticed the plate spring on those is bent in a bit different way. On the switches that have stopped clicking, the outermost "arms" of the spring, are slightly bent towards the bottom of the switch, in such a way that if you lay the plate spring on a flat surface, it's not looking flat.
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It might be hard to see but if you look closely at the outer part of the spring, you can see it is not in line with the rest of the spring. Those visible "kinks" or "bends" on the outer arms, i think are there to provide sort of a buckling point around which the entire spring inverts. I did a mistake of straightening those first, and while it STILL MADE THE SWITCH CLICK AGAIN, it altered the feel a little bit - i would not reccomend doing that. what you want to try to do, is just gently bend the arms back, so that the spring looks close to absolutely flat - it has to be able to stay in a stable state when flipped in BOTH directions, from what i understood while playing with the switch. So the spring should not be pre-bent too much in any direction. What i think happens over time is the spring fatigues with use, and gets slightly bent towards the switch bottom. this moves the flipping or, buckling "point" more towards the bottom of the switch, until the spring CANNOT flip before you already bottom out the switch, hence there is NO click at all. I have tried that on few switches, and all of them eventually started clicking, It is not a precise method in any way, because the bending has to be done very delicately and just a slight amount, maybe there could be a tool made in which you could just place the plate spring and press on it to bend it back just the right amount everytime. Doing it with fingers or pliers though, it's possible to bring the click back! I might try to do a small video soon explaining it more visually. I hope somebody finds this interesting. Cheers! :)

User avatar
jsheradin

05 Nov 2022, 18:25

Did you try compressing the damper pad in the non-clicky switches? I've had good luck just pressing super hard on a switch for a few seconds to bring the click back without ever opening them.

viewtopic.php?f=7&t=25158

Cool to see another method though! These switches have great potential but they're just a pain to open and keep closed again.

User avatar
browncow

05 Nov 2022, 18:34

jsheradin wrote:
05 Nov 2022, 18:25
Did you try compressing the damper pad in the non-clicky switches? I've had good luck just pressing super hard on a switch for a few seconds to bring the click back without ever opening them.

viewtopic.php?f=7&t=25158

Cool to see another method though! These switches have great potential but they're just a pain to open and keep closed again.
Hey, before reading your thread i also wondered if the rubber pad could be the culprit. That occured to me when just for the sake of it, i tried actuating a switch that was put back together, but didnt have the bottom housing pushed all the way in (leaving a gap of like 0,1mm between two parts of the housing.) The switch clicked! but so did the switches which i have bent the plate spring back and did not touch anything on the bottom. What i think of it now, after reading your thread, is that it must be probably those two factors at once, until the spring just cannot buckle. From what i understand, if the spring is close to perfectly flat - to make the buckling possible, in both directions. If you remove the pad - you're giving the out-of-shape spring just a bit more clearance to travel down, and buckle. same thing happens, if you dont push the housing in all the way during reassembly. however if you mess with the spring a bit, and try to bend it back into being close to flat - it starts to buckle properly without touching anything else. Thanks for a reply! :D

User avatar
browncow

25 Nov 2022, 20:58

Update: while i managed to restore few switches very well, it is a tedious process and i wanted to fix this board quickly, so i ended up desoldering switches from other chicony board that had a broken controller and soldering them onto this one as they felt almost brand new. I'm going to try to restore the rest of the broken switches in the future to use in maybe something scratch-built. :D
Here are some pics of the restored board, repainted switchplate and a set of keycaps i got for next to nothing with a cherry MY board. I think despite the different font they work nicely with the colours of the original modifiers. Shame i didnt have the original TAB key. the colour of the font seems to be almost spot on dark beige that original caps have as cap colour.
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original rusty switchplate. Very well made though, with a punching machine (there are obvious marks, i work at one of these machines
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re-painted with some enamel.
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Cherry MY caps on most keys. i had about half of original caps.
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The colours of the caps are almost reversed :D

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