[GreenKeys] AN/UGC-143A teleprinter info/parts wanted - long shot

[Nick England]

Progress report! -
I managed to trace some wires from the keyboard through the printer chassis
and into the control unit.
I found one flaky connection was the "keyboard attached" line, so I added
some shims under the DB37 where the keyboard plugs into the printer
chassis.
Et Voila! The boot-up process now recognizes the keyboard.

I can type on the keyboard and print letters (a process involving four
Z80s, shared memory, and four USARTs).
But I can only type W,E,Y,U,X,C,N,3,4,7,8, space, and LF - now to figure
out where the missing letters are going astray - I suspect they are hiding
inside the keyboard.

Nick England K4NYW
www.navy-radio.com


On Sun, Apr 20, 2025 at 2:23 PM Nick England <navy.radio at gmail.com> wrote:

> The keyboard is attached via a DB37 (no documentation on what signal/power
> is on there)
> http://www.navy-radio.com/tty/ugc143/IMG_1452.JPG
>
> The keyboard processor board has two 5v regulators on it and its logic
> chips seem to have +5 OK - I was hoping to find just a shorted tantalum
> killing a power rail, but no such easy problem! (and the damn thing is
> conformal coated so a pain to make measurements.)
> http://www.navy-radio.com/tty/ugc143/IMG_1460.JPG
>
> It looks like the keyboard itself and the fluorescent character display
> are standard commercial parts - they are connected to the processor board
> via ribbon cables
> http://www.navy-radio.com/tty/ugc143/IMG_1461.JPG
>
> Access is via the bottom of the keyboard so it is pretty awkward - I may
> make an extender cable so I can more easily probe things.
> First I will look at the Z80 to see if it active (I think it must be
> because during power-on the character display gets initialized and then it
> says "PLEASE WAIT". Then the printer finishes its power-on sequence and
> prints "READY", but the BIT status code says "keyboard not installed",
> http://www.navy-radio.com/tty/ugc143/IMG_1463.JPG
> http://www.navy-radio.com/tty/ugc143/IMG_1465.JPG
>
> Then I will look at the TX and RX lines on the keyboard USART that talk to
> a USART in the control unit.
> There must be some attempted handshake during power-up BIT because the BIT
> status at that point says "keyboard not installed". And thereafter the
> internal software thinks this is an RO with no keyboard.....
>
> But I got no flow diagram or much about how the controller, keyboard, and
> printer microprocessors actually interact, other than that they use serial
> links.
> http://www.navy-radio.com/tty/ugc143/message-generation-01.jpg
>
> -----------------
> Keyboard unit A3
> applies serial data directly to backplane interface A2A1A3A1, backplane
> A2A1A1, I/O connector assembly
> A2A1A2 and I/O connector assembly A1A4 to the receiver section of a USART
> on port card A1A2A1 of electronic
> control unit A1. The electronic control unit A1 USART converts the data
> back to parallel form for processing
> by the IOC microprocessor and storage in the dual port RAM of DSC A1A2A3.
> Based upon receipt of
> KYBD ONLINE data in the dual port RAM, the storage control functional
> group ( paragraph 3-4) develops
> appropriate control signals. Control signals are sent back to keyboard
> unit A3 by reversing the path followed by
> the KYBD ONLINE data except for the substitution of USART transmitter
> section for receiver sections and
> receiver sections for transmitter sections. Character keys typed by the
> operator, thereafter, follow the same path
> as the KYBD ONLINE data to be stored in the DSC dual port RAM. The control
> microprocessor on the DSC
> (figure FO-5-3) transfers data in the DSC dual port RAM into the print and
> communications lists of the buffer
> memory. From that point keyboard originated characters are transferred to
> the print and transmit buffers in the
> dual port RAM for routing to the message print and message transmit
> function circuits.
> ------------------
>
> Nick England K4NYW
> www.navy-radio.com
>
> On 4/19/2025 2:33 PM, Nick England wrote:
>>>
>>> This is a circa 1988 machine I am trying to revive with not enough
>>> technical info. To my surprise the control unit and the printer appear to
>>> work - but not the keyboard.
>>> A description and photos of the beast are at
>>> http://www.navy-radio.com/tty/ugc143a.htm
>>>
>>> It, of course, uses multiple microprocessors - It will pass BIT
>>> diagnostics except that evidently the printer Z80 isn't talking to the
>>> keyboard Z80 so it doesn't think that the keyboard is actually plugged in.
>>> I believe that the keyboard Z80 is alive because the one-line display on
>>> the keyboard says PLEASE WAIT.
>>> I have an operation and troubleshooting manual which covers the built-in
>>> test routines, but that stops at the "replace the keyboard assembly" stage.
>>>
>>> So does anyone have a spare keyboard or a tech manual with schematics
>>> that I could borrow?
>>> This is a very long shot, but you never know what someone has
>>> accumulated.
>>>
>>> Cheers,
>>> Nick England K4NYW
>>> www.navy-radio.com
>>>
>>>
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