[GB] [IC] BT-USB-Hybrid controllers for Model M 122, M2, Unicomp M

Please make a BT-USB-Hybrid controller for other Model M variants:

Model M 122
10
48%
Unicomp Model M/Model M 4th generation/Lexmark Model M
6
29%
Model M2
5
24%
 
Total votes : 21
I'd love to convert one of my Lexmark Ms.
ScottPaladin
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Unread post07 Jun 2018, 15:20

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ScottPaladin wrote:I'd love to convert one of my Lexmark Ms.

Do you have an idea how to deal with the lack of an SDL bay? The only preexisting opening is the hole where the PS/2 cable exits the case. This opening could be used to hold a Mini or Micro USB connector, but it would have to be glued or screwed to the inside of the bottom shell.

Since all Model M bottom covers, including 4th generation boards, seem to have retained mounting pins for the 170x50 mm controller boards, I would want to use them to hold the controller board and make a daughterboard to replace the original controller boards mounted in the top right corner directly below the LED overlay. The daughterboard then would have to be connected to the main controller board by ribbon cables.

However, my current design requires the user to throw a switch to change between BT and USB mode - but there are no preexisting openings, or at least no other suitably sized openings, for a slider or rocker switch in the cover of a 4th generation Model M. I could modify the circuitry so that the mode of operation will change automagically once a USB cable is plugged in though, but that would exclude special use cases (s.a. charging the battery while in BT mode).

What do you think?
mind_prepared

Unread post07 Jun 2018, 22:57

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mind_prepared wrote:
ScottPaladin wrote:I'd love to convert one of my Lexmark Ms.

Do you have an idea how to deal with the lack of an SDL bay? The only preexisting opening is the hole where the PS/2 cable exits the case. This opening could be used to hold a Mini or Micro USB connector, but it would have to be glued or screwed to the inside of the bottom shell.

Since all Model M bottom covers, including 4th generation boards, seem to have retained mounting pins for the 170x50 mm controller boards, I would want to use them to hold the controller board and make a daughterboard to replace the original controller boards mounted in the top right corner directly below the LED overlay. The daughterboard then would have to be connected to the main controller board by ribbon cables.

However, my current design requires the user to throw a switch to change between BT and USB mode - but there are no preexisting openings, or at least no other suitably sized openings, for a slider or rocker switch in the cover of a 4th generation Model M. I could modify the circuitry so that the mode of operation will change automagically once a USB cable is plugged in though, but that would exclude special use cases (s.a. charging the battery while in BT mode).

What do you think?

Well, both of my Lexmark M's have SDL bays, so I hadn't really been thinking about how to work around the lack of one. I'm not one to balk at cutting a new hole though. Couple of files and maybe a 3D printed shroud solve most problems of that type.

I'm partial to having a physical switch to choose mode, even if it means I've got to cut the plastic to make room for it, but I know not everyone would agree. A possibility would a three position switch: force USB, force BT, and cable select. That would give a lot of flexibility, and anybody who wants to use cable select could just solder/jumper into cable select mode.
ScottPaladin
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Unread post11 Jun 2018, 15:39

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ScottPaladin wrote:
Well, both of my Lexmark M's have SDL bays

in that case there is no problem at all. My reservations only apply to 4th generation boards, the last revision of the M series without an SDL bay and a fixed cable exiting the case at the top right corner. If your board has an SDL bay then you're good (whether your controller has an SDL connector + SDL cable doesn't matter) :)
mind_prepared

Unread post11 Jun 2018, 18:49

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