Thanks, Eric - and thanks to all who have responded with helpful info and links to manuals.

One of the reasons for the session yesterday was for me to deliver a 120vdc 1a supply to provide enough oomph for the punch.

I understand a more about the punch activation now - Note 13 on the P90.954 WD that you sent is a good explanation - The M19 K/KT/T works essentially like the 28ASR with which I am familiar, the main difference being that the M19 punch is powered by electromagnet and the M28 punch is powered by the motor shaft.

K mode - no punching

KT mode - Cam Pulsing Contacts on the keyboard drive shaft pulse the punch magnet

T mode - the U-Bar Contacts pulse the punch magnet (meaning punching is not restricted to machine speed as Eric V. pointed out)

Cheers,

Nick England K4NYW
www.navy-radio.com

On Sat, Sep 23, 2023 at 10:19 PM E. <[email protected]> wrote:

Being a 15/19 guy...

1 — the perforator is not powered by the loop - instead, it is powered by what would have been the 120VDC rectifier on the backside of the 19 table (takes a lot of amps to punch - a 1A rectifier is usually good). You can test it by removing the keyboard and connecting alligator clip test leads from the rectifier, to the correct terminals on the keyboard (and of course with the correct polarity)... but be careful 'cause that is a lot of juice to accidentally bump.

The switch on the TT - as mentioned before, powers the punch with the switch is down, turns it off when the switch is all the way up or allows you to see what you are punching on the printer, when set in the middle. The AC power switch does not need to be on when it's only set to punch (but on for the rest preferably).

2 — When you press a key, there is a bar that slides underneath the keyboard, to the punch - and that allows the punch to select the proper Baudot code to punch... no cam shaft needed.

3 — Attached - the best diagram you may find, but mileage will vary :) .

> On Sep 23, 2023, at 4:32 PM, Nick England <[email protected]> wrote:
>
> I tried to help out a fellow with a M19 today - and I know nothing about that era equipment - first time I had touched one. So no surprise that I wasn't too helpful figuring out where a stray wire was supposed to go.
>
> Symptom - This punch magnet is always on in T and KT, off in K.
>
> Question 1 - can you remove and standalone test just the keyboard/perf assembly with 120vdc (obviously having to rotate the driveshaft by hand).
>
> Question 2 - is the punch magnet supposed to only get activated by the closure of the cam contact on the keyboard shaft? Or is it one of those oddball things that is always on except to punch via spring power?
>
> Question 3 - is there a good simplified WD for a dummy like me?
>
> Thanks,
> Nick the M28 guy
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