Harris Smart Terminal, xwhatsit Model F to USB

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OldIsNew

05 Oct 2017, 06:54

I came across Sangdrax's excellent work and background info on this GH post: https://geekhack.org/index.php?topic=90 ... msg2436488 so when I came across the same board for a reasonable price I went for it.
orig_DT.jpg
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This one is dated July 27, 1978.
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Sangdrax did a great job documenting the board - I thought I'd have a go at converting it and add a few more pics too.
I's an interesting capacitive board:
open1_DT.jpg
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backplane2_DT.jpg
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PCB_back_DT.jpg
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front2_DT.jpg
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PCB_front_DT.jpg
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The rows are wired to pads under soldermask in the PCB and the columns to the copper leafs :
contacts_DT.jpg
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Sangdrax figured out the board was 8 row by 16 columns and I thought I'd put a few more pics of the IC connections (labeled with arbitrary numbers and letters):
Rows
Rows
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Columns
Columns
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Then desoldered the ICs and wired up the xwhatsit:
wired1.jpg
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And much to my relief, it worked! Voltage threshold seems good between 150 - 160 and I went ahead at set it at 158 like Sangdrax. Once I was sure everything was good, I went ahead and hooked up the lock lights to three of the onboard LEDs.
lights1.jpg
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And retrobrighted the blue keys
retro.jpg
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I need to touch up the case but I'm really pleased with this board and am going to be using it a lot.
after1_DT.jpg
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caselights2.jpg
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caselights3.jpg
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Thanks again to Sangdrax for the heads up and tips on this board!

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Sangdrax

05 Oct 2017, 07:29

Definitely take the time to lube the plungers on the board if you get a chance. It makes everything so smooth. The dried gunk on mine sure made it look like it was that way originally too. Best way to do it is press the plunger down and apply to the cross stem underneath instead of trying to work around the springs up top.

It's still my daily board over even my beamspring. Love this thing. I can post my layer layouts too if that would help at all. My favorite is basically the one that makes it like a TKL plus media keys.

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zslane

05 Oct 2017, 19:01

I can't tell what the color the keycaps are due to the inconsistent lighting. But those sphericals are amazing!

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OldIsNew

06 Oct 2017, 07:25

Sangdrax wrote: Definitely take the time to lube the plungers on the board if you get a chance...
It I can post my layer layouts too if that would help at all.
I lubed the plungers and yes - it does make a nice difference for sure! If you get a chance to post your layer layouts those would be great to take a look at - thanks!
zslane wrote: I can't tell what the color the keycaps are due to the inconsistent lighting. But those sphericals are amazing!
I'd say light blue/teal is best description of color. I've just got a cheapo cell phone camera.

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Sangdrax

06 Oct 2017, 09:10

Yeah, they're definitely teal. A photo in natural light will show it the best.

Oh, and I made the layout thing. I pretty much just use the bottom one all the time unless I need to punch in a bunch of numbers.

Image

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zslane

06 Oct 2017, 18:45

Dat blue! So beautiful!

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paecific.jr

06 Oct 2017, 20:55

What does it sound like? Can you post a video?

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Sangdrax

12 Oct 2017, 15:33

You can really hear the springs in it and has a loud whack on the bottom out. Insanely pingy for a linear design as well. I'd really like to see a video too, even a phone one, for comparison purposes.

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