Consul 262.3 keyboard with Hall Effect switches

John Doe

08 Jun 2021, 04:55

For some reason I'm trying to convert this hall effect kb to USB but I failed, good side is I dont feel sad at all.
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According to my digging, the switches, or specifically the sensors made by Tesla from Czech Republic during 90s, are pretty friendly. There're two points we can call, the first is the sensors are "hold" type which means it could work just like switches based on contact, this's a big help for conversion like using a controller replacer. The second is out of my expection as I havn't seen types like this yet. That's saying, if we name the 4-terminal sensors pins from 1 to 4, then 1->VCC, 4->GND, 2->input and 3->output, but if we swap the 2 and 3 like 3->input and 2->output, it's still working.
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Biggest chanllenge for this project is it's using 2 of N encodes other than a matrix, which means the best result we'll get is 1Key rollover even we could make it with the original PCB. But surely we could make it better if there's a new PCB to fit the layout with a matrix, unfortunately I dont have skill to draw one.
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Anybody has done such job or any more info could do a favor?

gipetto

09 Jun 2021, 12:27

I wouldn't bother with a custom pcb. From other threads any solder rework done tends to fry the hall effect sensors. but i'm sure a controller replacement would be the easiest route.
I assume a hold type hall effect would be similar to the alps em encoder datasheet. they have 3 pins for each sensor, vcc, gnd and a third pin which outputs 5v or so based on state. it makes sense that there is a fourth pin to turn on and off each row or column for matrix scanning.

John Doe

09 Jun 2021, 13:18

gipetto wrote:
09 Jun 2021, 12:27
I wouldn't bother with a custom pcb. From other threads any solder rework done tends to fry the hall effect sensors. but i'm sure a controller replacement would be the easiest route.
Yep, it's risky to remove the sensors off but that's inevitable seems. Probably jumpers the switches to fabricate matrix is another option, but that's not too much safer, and it's ugly for some ppl's taste.

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