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Author Topic: Help me fix my Model M!  (Read 1426 times)

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Offline doyouevenclack?

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Help me fix my Model M!
« on: Mon, 08 April 2013, 13:58:05 »
Newbie here! I just bought an 82g2383 and a 1391401. For the 82g, I just took the keycaps off and cleaned them. It works perfectly! The problem is the 139....

I didnt test it when I received it and instead took it all apart. I washed (soap and water) the top and bottom plastic plates, keycaps, and the main unit with the keys still in place (I took the pcb board off). After a few hours of drying, I plugged it in and it makes a beeping sound as if multiple keys are pressed (I hot swapped, but now I know that's bad). This was probably due to not enough drying so I waited a day and tested again. Now, the keyboard gets passed POST (all three lights also blink once), but at the password screen, none of the keys do anything. NUMLOCK light is on, but wont toggle. Neither will the scroll lock or CAPS.

At first I thought the pcb board is fried so dismantled the 82g and used the 139's pcb board and it worked fine. This means the problem is not the computer or the pcb electronics. It must be something affecting the key presses, maybe the membrane? Could water damage them? To visually check, I would have to do the nut and bolt mod :(  Maybe I could use a multimeter and check presses using the membrane electrodes? Any helps with troubleshooting are appreciated.
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Offline E TwentyNine

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Re: Help me fix my Model M!
« Reply #1 on: Mon, 08 April 2013, 15:13:33 »
If you had tested it beforehand and then it happened I'd definitely say water.  You haven't, but still going to go with that.

You may just want to let the keyboard sit somewhere for a few days.  Try it again, see if the behavior changes.
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Offline fohat.digs

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Re: Help me fix my Model M!
« Reply #2 on: Mon, 08 April 2013, 15:31:12 »
There are several membranes pressed tightly together. I would guess that if a Model M was completely submerged, capillary action took water all the way in between all the membranes.

It is hard to imagine that it would dry thoroughly in less than a week, minimum. If you used soap, then soap residue could be in there and have additional deleterious electrical effects.

Doing the bolt mod is a pain, but you could completely clean every part and start "fresh".
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Offline mich

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Re: Help me fix my Model M!
« Reply #3 on: Mon, 08 April 2013, 19:34:50 »
Quote from: doyouevenclack? on Mon, 08 April 2013, 13:58:05
Maybe I could use a multimeter and check presses using the membrane electrodes?
Sure you can.

Normally there should be no connection between any trace on the upper membrane and any trace on the lower one. If there is a connection, it's water.
OTOH, when you press some key, it should connect some lower trace to some upper trace. If this doesn't happen, you have a damaged membrane.

BTW, check the cable as well.
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Offline PointyFox

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Re: Help me fix my Model M!
« Reply #4 on: Mon, 08 April 2013, 19:50:56 »
Take it apart, use compressed air to dry it, turn off the computer, plug the keyboard in, then turn on the computer.
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Offline doyouevenclack?

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Re: Help me fix my Model M!
« Reply #5 on: Thu, 11 April 2013, 13:43:56 »
Update!
I just set it sit and now the capslock and numlock work. The is still water left since its not working completely but it's getting there. Ill give it another week and if its still acting funny, i'll open it up and do the mod.
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