Teletype shutting down when connecting a backlit keyboard

Monome
#1

I recently got a Teletype and it did not come with the original keyboard but a much bigger one so I bought a small mechanical keyboard to use with it.

I received the keyboard today and at first things seemed to go very well. That keyboard has built-in backlighting and it was on when I plugged it the first time. I turned the backlighting off because I didn’t need it and kept typing and generating nice voltages. At some point I tried putting the lighting on just to see and when it reached the max lighting, Teletype immediately shut down. I got a bit scared, unplugged the keyboard and turned the modular off and on again and thankfully things seemed back to normal. Except that whenever I plug the keyboard it seems to start at full backlight and TT shuts down immediately. I tried to dim the lights as soon as the keyboard is plugged or to start with the keyboard either plugged in or not and nothing works so far.

I’m trying to find a way to make the keyboard initialize in a “no lights” state but so far plugging it in my PC and trying different things hasn’t been a great success…

Is this a known issue and is there a way to get around this ?

What I don’t understand is that it worked fine the first time I plugged the keyboard. Is there something in the module that could have fried or something like that ?

This is a bit scary for a $500 module… :cold_sweat:

Edit : my case is a 7U Intellijel with a TPS80W power supply that has lots of power available (I’m probably using about 20-30% of what it can supply).

#2

Your case power doesn’t matter since Teletype has its own (anemic) 5V regulator. You will want to use an external power supply for the keyboard. Look into the “Offworld” adapter design from monome.

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#3

Thanks for the answer but there’s no way I’m going to use an external power supply for a keyboard. My goal is to remove clutter and cables, not add more :slight_smile:

As I mentioned previously, the TT worked fine with the keyboard initially, and it was lit for maybe 10-20 seconds initially before I turned it down. Now it just shuts down right away and I think it stops powering the keyboard (at least not enough) as I can’t adjust the lighting using the proper keys.

I might have to return that keyboard and get something else but it was the only one with the size I wanted (75%) that looked good enough and was within my price range ($50) :

#4

I have a Logitech backlit keyboard that I switch between my computer and Teletype with a passive USB switch and it doesn’t have this issue. (It does freeze audio on my computer for a second when I switch though.) IIRC, the lights turn off when I switch it to Teletype.

#5

Well you could always mod your Teletype to push 5V straight from the case supply. Or use a less power-hungry keyboard.

#6

I just wanted to confirm whether that behaviour is normal/expected or not before returning the keyboard and getting another one that has no backlighting…

Also, I like Warren Ellis too :wink:

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