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geekhack Community => Keyboards => Topic started by: mausch on Wed, 09 March 2011, 18:23:24

Title: Model M with some issues
Post by: mausch on Wed, 09 March 2011, 18:23:24

Hi everyone, first-time poster and overall keyboard newbie here.
Just got a NIB Model M (a '96 42H1292 by Lexmark), and after plugging it in I was horrified to discover that some keys didn't work.
More concretely, these are the keys that don't register (tested with Aqua's KeyTest): B,N,Space,/,Right Alt, Left/Down/Right arrows, Minus on keypad
I first thought it was an adapter issue (I'm using a PS/2-USB adapter), but then discovered that tilting the board 45 degrees from the side and gently tapping it would enable these keys... as long as I don't put it back to horizontal.
I'm pretty sure this happened during shipping, maybe something unsoldered? Anyone seen this? If I were to open the board, what should I look for?

Thanks
Mauricio

Title: Model M with some issues
Post by: mausch on Thu, 10 March 2011, 12:27:58

Thanks Ripster! I was in the middle of reseating the arrow keys, and it suddenly started working. Used the board for about 4 hours with no issues, then the Enter started failing. Then it started working again (without me doing anything). Then a whole lot of keys in the lower row failed (curiously not the ones that used to fail before). Then the original failure started again.
So I'm sending it back. No Model M for me :-(

Title: Model M with some issues
Post by: theferenc on Thu, 10 March 2011, 12:34:10

I would try pulling all of the keys and reseating them carefully prior to sending it back. It really is worth it if you can get it working.

Title: Model M with some issues
Post by: mausch on Thu, 10 March 2011, 13:49:33

Cheers, gonna give it another shot!

Title: Model M with some issues
Post by: keyb_gr on Thu, 10 March 2011, 15:27:46

It might also be a problem with controller PCB to membrane connection, though I don't see how that would be happening. On the other hand... didn't Unicomps drop membrane connectors for a more dubious kind of making contact at some point? I don't think this already affected 42H1292s though.

Title: Model M with some issues
Post by: ch_123 on Thu, 10 March 2011, 16:50:39

The 42H1292 introduced the new controller type used in Unicomp's current keyboards.

Title: Model M with some issues
Post by: mausch on Thu, 10 March 2011, 16:56:53

Popped off and reseated the failing arrow keys, / and keypad minus, about 20 times, to no avail.
I also reseated a couple other working keys, just to make sure I was doing it correctly, and they continued to work just fine.
Quite upset about this, I was really looking forward to replacing my crappy rubber dome board :-(

Title: Model M with some issues
Post by: ch_123 on Thu, 10 March 2011, 17:00:21

Generally the keycap trick is used to fix the springs coming loose - which you can tell if the keys dont feel right. If the keys feel like the working keys, and dont work, you're looking at some sort of electronics failure.

Title: Model M with some issues
Post by: mausch on Thu, 10 March 2011, 17:32:35

Yup, the keys feel just right, springy and clicky, the keyboard is spotless, yet these keys won't register... and since it's intermittent and a gentle smack "fixes" it, I'm guessing something's loosely soldered, but since the board is "new" I'm really hesitant to open it.
Plus, I'm a klutz :-)

Title: Model M with some issues
Post by: Surly73 on Thu, 10 March 2011, 19:26:30

I wonder if it isn't just badly in need of a bolt mod.  If the "sandwich" isn't held together tightly the membrane part of the equation will register intermittently.  If you have the proper 7/32" nutdriver you could pop the back off and check.  Alternatively, does there seem to be "stuff" loose inside if you shake it?

Title: Model M with some issues
Post by: theferenc on Thu, 10 March 2011, 19:35:50

Quote from: Surly73;309579

I wonder if it isn't just badly in need of a bolt mod.  If the "sandwich" isn't held together tightly the membrane part of the equation will register intermittently.  If you have the proper 7/32" nutdriver you could pop the back off and check.  Alternatively, does there seem to be "stuff" loose inside if you shake it?

This is my thought as well. It sounds more like the plastic just got too brittle, and then was jarred loose during shipping.

Title: Model M with some issues
Post by: mausch on Thu, 10 March 2011, 23:43:11

Just shook it a bit, and Enter and a lot other keys failed. Shook it a bit more, and now all keys work :-)
So it seems to be a matter of
(http://1.bp.blogspot.com/_6oloLRFEQRs/TNlM3EnRAAI/AAAAAAAAD0E/APKAE-JzhoY/s1600/Violence_Motivational_Poster.jpg)

Question is, how long will it work?
BTW nothing sounds loose within.

Title: Model M with some issues
Post by: Surly73 on Fri, 11 March 2011, 06:45:05

I would seriously pop the back and see if it needs a boltmod as opposed to more serious problems like a fried controller or a completely worn out membrane.  Since it's a recent purchase I can understand simply returning it too but the fix might be something that you'd end up doing anyways...

Title: Model M with some issues
Post by: mausch on Sat, 19 March 2011, 17:31:22

I returned the keyboard, just received a replacement, and it has similar failures (a different failing key set, but still). AquaKeyTest screenshot:

(http://img535.imageshack.us/img535/8757/tecladofalla2.png)

Tried reseating again, to no avail. So I'm gonna try to cut my losses and sell it as it is. :-(