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Author Topic: IBM Model M - typing is slow and the springs feel weak  (Read 2163 times)

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Offline Barabbas

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IBM Model M - typing is slow and the springs feel weak
« on: Sat, 07 April 2012, 16:15:20 »
This morning I got my first "real" mechanical keyboard, the long awaited "IBM Model M" (1391412)
made in the UK (eather by Lexmark or it is just the chip).  It has a Swiss layout and came very,
very clean. Also I got it for 1$.

I tested it on my old computer and it worked right away, although it doesn't work on my newer MB
(Gigabyte MA-880GA-UD3H), so I was thinking about the ways I could make it to work.

I disassembled it, cut the rivets and cleaned everything in a dishwasher (yes, I know ABS wraps at
50°C), it came out STERILE, and the birth certificate miraculously survived!

Tomorrow I am about to do a "bold mod" on this thing and I have several questions:


- typing on it feels HORRIBLE (actually function keys are OK), the springs seem very weak, I know
  this isn't how it is supposed to work since I experienced typing on a brand new "Model M" (122 key
  1397003 I believe, the friend got it) and this isn't the feeling I was looking for :(.
  Do I need to buy a new set of springs or did the rubbery mat just got sticky or something?

- is there a chance that this KB works on my newer MB using some kind of PS/2 -> USB converter (and
  which one)?

- which screws for the bold mod again?

Also, I know my way around electronics (quite well actually), and I am about (some time this month)
to build a new logic board for this thing, I found some plans and know some people who did this
exact thing before. I was wondering if anyone here have tried to build his own logic board and are
there more plans/ideas that I could use. I was planing to make it work as both USB and PS/2 device
and also to have some kind of integrated USB hub and a small LCD display.
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Offline fohat.digs

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IBM Model M - typing is slow and the springs feel weak
« Reply #1 on: Sat, 07 April 2012, 21:03:25 »
Screws for the bolt mod are hard to find because they are so very small. Also, I feel that the front row (spacebar side) works better with self-tapping screws than nuts & bolts because of the ridge in the plastic. Do not tighten any more than the minimum necessary.

There are several good wikis for this.

I have never felt a whole lot of difference between new and old springs, you may have some other problem like heavy sticky dirt or soda residue.
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Offline mich

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IBM Model M - typing is slow and the springs feel weak
« Reply #2 on: Sun, 08 April 2012, 04:33:58 »
Late (around '95) Lexmarks are lighter and I don't really like them. Maybe a bolt mod will change it, but I've never tried.

The problem with new motherboards is likely caused by this: http://ps-2.kev009.com/ohlandl/keyboard/modify_keyboard/Model_M_Modifications.html
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Offline Barabbas

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IBM Model M - typing is slow and the springs feel weak
« Reply #3 on: Sun, 08 April 2012, 05:21:25 »
Thanks for the link:

Quote
After looking at the clock and data lines with a scope and comparing to a
newer keyboard, it seemed that the 'logic high' state on both Clock and Data
lines was fractionally lower when the IBM keyboard was connected.

Another relevant factor is that the older technology used on the IBM
keyboard's controller PCB requires more power to operate than newer keyboards.
The IBM draws around 112mA from the interface, whilst a modern keyboard draws
1.2mA. These figures are with the 3 status LEDs (NumLock, CapsLock,
ScrollLock) off. Each of these draw around 12mA when lit on both keyboards.
It confirmed my original doubts.


I will try the resistor hack today and if it works and if that fails I will probably try and
build the new logic board, since I already wanted to add some functionality to
it. I can't decide on which of these projects to base my own:

httq://mg8.org/rump/
httq://www.schatenseite.de/dulcimer.html
httq://wiki.razmjenavjestina.org/index.php/TypeM_-_modifikacija_IBM_Model_M_tastature
httq://www.pjrc.com/teensy/
httq://geekhack.org/showwiki.php?title=Island:8406


Anyway, the Lexmark case is not all that well built as the US made Model M, I
thought that it was the "McGurk Effect", but now I am relatively sure it is
not, since the case bends easily (hell even my old rubber dome KB is sturdier
than that).

Also, the rubber mat was covered with fine dust of unknown origin, I cleaned
it and I am not sure what it is an should it be present.
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Offline TacticalCoder

  • Posts: 526
IBM Model M - typing is slow and the springs feel weak
« Reply #4 on: Sun, 08 April 2012, 08:38:23 »
Can't the power issue be solved by using a "blue cube" USB-to-PS/2 adapter?

I've bought two such cubes in a group buy and they're working fine.   Although for me the mobos have always all been compatible with my Ms: but I wanted to benefit from the hot-plugging (you're not supposed to hot-plug on the PS/2 port but you can hot-plug on USB).

(at least if I remember what I read on GH correctly ; )
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HHKB Pro JP (daily driver) -- HHKB Pro 2 -- Industrial IBM Model M 1395240-- NIB Cherry MX 5000 - IBM Model M 1391412 (Swiss QWERTZ) -- IBM Model M 1391403 (German QWERTZ) * 2 -- IBM Model M Ambra -- Black IBM Model M M13 -- IBM Model M 1391401 -- IBM Model M 139? ? ? *2 -- Dell AT102W -- Ergo (split) SmartBoard (white ALPS apparently)

Offline mich

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IBM Model M - typing is slow and the springs feel weak
« Reply #5 on: Sun, 08 April 2012, 09:13:31 »
Yes, it can, but shipping one to my place would cost more than half of my Ms together. And the Chinese no-name adapters are a lottery, I've bought two and both had a different set of bugs :)
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Offline Crake

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IBM Model M - typing is slow and the springs feel weak
« Reply #6 on: Sun, 08 April 2012, 09:41:27 »
Do the new Unicomp USB ones have problems?
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