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DC50 keyswitches [message #370451] Mon, 09 July 2018 12:09 Go to next message
Wayne Stewart is currently offline  Wayne Stewart
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Registered: September 2012
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I have a keyboard with quite a few dead DC50 key switches, the ones with the angle on the shaft. I desoldered a few and tried exercising two of them a bunch with no luck. I seemed to recall reading somewhere that spraying contact cleaner down the shaft wouldn’t work with these but I figured I had nothing to lose. I spent half an hour looking for the contact cleaner before I gave up. What else can I try? WD40? They’re dead anyway so why not. Sprayed the shaft on 2 key switches, worked them up and down half a dozen times. Checked them both with my ohm meter and they both now work.. This feels like the wrong way to do it but I'll see how they last.
Re: DC50 keyswitches [message #370471 is a reply to message #370451] Mon, 09 July 2018 16:13 Go to previous messageGo to next message
Michael Black is currently offline  Michael Black
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On Mon, 9 Jul 2018, waynejstewart@gmail.com wrote:

> I have a keyboard with quite a few dead DC50 key switches, the ones with
> the angle on the shaft. I desoldered a few and tried exercising two of
> them a bunch with no luck. I seemed to recall reading somewhere that
> spraying contact cleaner down the shaft wouldn’t work with these but I
> figured I had nothing to lose. I spent half an hour looking for the
> contact cleaner before I gave up. What else can I try? WD40? They’re
> dead anyway so why not. Sprayed the shaft on 2 key switches, worked them
> up and down half a dozen times. Checked them both with my ohm meter and
> they both now work. This feels like the wrong way to do it but I'll see
> how they last.
>
The keyswitches I've had problems with have been due to gunk and other
things making the keys stick so they can't go down. If they keys don't
press down, then that seems to be the case, rather than bad contacts.

I've fixed sticky keys by applying some rubbing alcohol, let it sit for a
bit then work the key, hopefully that will erase the stickiness. The
rubbing alcohol is supposed to evaporate, leaving nothing. Wait, some of
it can come with scents and other things that can't be good. I know I've
used 70% which was just water and alcohol, othing else added. But then
more recently, I noticed 90% or maybe a bit higher, and no additives, and
I've used that when cleaning things.

Michael
Re: DC50 keyswitches [message #370476 is a reply to message #370471] Mon, 09 July 2018 17:52 Go to previous messageGo to next message
Anonymous
Karma:
Originally posted by: frank_o_rama

If you try isopropyl alcohol, turn them upside down to drain out any residue. This generally only works for sticky keys though, not dead ones. You could also try deoxit. Don't use WD40 as it gums up when it dries.

I have a datanetics keyboard as well, and haven't had any luck getting dead keys working again. I'm assuming I need a donor keyboard to just desolder working keys from. I fixed the dead encoder, only to find that 25% of the keys didn't work either.

Also, just to note, the later 2-piece/"stacked" keyboards are MUCH more reliable, plug into the same connector, don't use an unobtanium encoder, and are much more common. On those the key switches can actually be rebuilt. Might not fit into the same mounting area on the chassis though. Haven't tried that.

F
Re: DC50 keyswitches [message #370477 is a reply to message #370476] Mon, 09 July 2018 19:04 Go to previous messageGo to next message
Wayne Stewart is currently offline  Wayne Stewart
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Mine went up and down normally but didn't work.
Re: DC50 keyswitches [message #370520 is a reply to message #370477] Tue, 10 July 2018 13:33 Go to previous messageGo to next message
Wayne Stewart is currently offline  Wayne Stewart
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Anyways, unless something better comes up I've got a choice. Working now but may stick in the future or not working at all.
Re: DC50 keyswitches [message #370559 is a reply to message #370451] Wed, 11 July 2018 02:52 Go to previous messageGo to next message
Anonymous
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Originally posted by: groink_hi

Once the key switch is dead, it's dead forever. I posted something similar a few weeks ago, and that's basically the conclusion. The reason is that the switch uses a mylar diaphragm that contains two thin copper contacts. If the switch is dead, it is because of the contacts in the package - probably corrosion of some kind. No alcohol or anything else will work because the mylar diaphragm is sealed. You would have to somehow crack the outer case open, break open the mylar diaphragm, and then service the copper contacts. The person who comes up with a replacement of the mylar diaphragm would be rich overnight!
Re: DC50 keyswitches [message #370665 is a reply to message #370559] Fri, 13 July 2018 13:12 Go to previous messageGo to next message
Wayne Stewart is currently offline  Wayne Stewart
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I tried a number of more key switches with the WD40 and had poor luck, only getting 1 more working. I suspect I hit on 3 that weren't sealed all that well.
So I decided to take a non functional one apart and assess the situation. It appears to me that they should be repairable but reassembly might be a real pain.
Some crappy pics here
https://68kmla.org/forums/index.php?/topic/55192-dc50-take-a part/
Re: DC50 keyswitches [message #370699 is a reply to message #370665] Sat, 14 July 2018 01:28 Go to previous messageGo to next message
Michael J. Mahon is currently offline  Michael J. Mahon
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<waynejstewart@gmail.com> wrote:
> I tried a number of more key switches with the WD40 and had poor luck,
> only getting 1 more working. I suspect I hit on 3 that weren't sealed all that well.
> So I decided to take a non functional one apart and assess the situation.
> It appears to me that they should be repairable but reassembly might be a real pain.
> Some crappy pics here
> https://68kmla.org/forums/index.php?/topic/55192-dc50-take-a part/
>

How about just piercing the membrane and using contact cleaner.

It breaks the seal, but as long as the switch is used regularly, that
shouldn’t be a problem.

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
Re: DC50 keyswitches [message #370728 is a reply to message #370665] Sat, 14 July 2018 14:46 Go to previous messageGo to next message
Anonymous
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Originally posted by: frank_o_rama

try contacting this ebay seller. He may have some spare switches offline.

https://www.ebay.com/usr/puerto06

f
Re: DC50 keyswitches [message #370857 is a reply to message #370728] Mon, 16 July 2018 17:33 Go to previous messageGo to next message
Wayne Stewart is currently offline  Wayne Stewart
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Registered: September 2012
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Thanks, I may do that if either I have bad luck with the repairs or it proves to be too much of a pain doing the reassembly.
Re: DC50 keyswitches [message #371121 is a reply to message #370857] Sun, 22 July 2018 20:38 Go to previous message
Wayne Stewart is currently offline  Wayne Stewart
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Registered: September 2012
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Still couldn’t find my contact cleaner and haven’t had a chance to stop by any place that sells it so I tried buffing the contacts with super fine steel wool. Used crazy glue to glue the inside piece with the contacts back together then started reassembling everything. Wish I had tiny fingers, I dropped tiny pieces several times. Glued the outside shell together with crazy glue. Checked it with my ohm meter and everything’s good. 20 more to go!
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