[GreenKeys] Model 14 keyboard adjustment

[Eric Moore]

https://deramp.com/downloads/teletype/Model%2015/loop%20interface%20board/Schematic%20Rev%20A.pdf

Verified the printer loop at 60ma. The keyboard loop runs at 15V, not sure
on the ma, but not sure it matters much as it just opens and closes without
driving any coils or similar.

I am fairly certain my issue is the contacts somehow. I see voltage (and
continuity) up to those contacts, but despite cleaning fairly extensively
with contact cleaner, they are still too high resistance. I am going to try
some sandpaper today and see what is what...

-Eric

On Sun, Aug 6, 2023, 12:10 AM Gerry Block <gblock at sbcglobal.net> wrote:

> typo:  "60 ma"
>
> Sent from my iPhone
>
> On Aug 5, 2023, at 10:07 PM, Gerry Block <gblock at sbcglobal.net> wrote:
>
> eric
>
> what does your loop schematic look like?  sketch it out and enclose photo.
> what is the loop power supply voltage.
> what is the series resistance to make the 60ms.
> are you sure it is running at 60 ms?
> where is the scope probe grounded and where is the loop supply grounded?
> i doubt it is the contacts.
>
> gerry
>
> Sent from my iPhone
>
> On Aug 5, 2023, at 5:49 PM, Eric Moore <mooreericnyc at gmail.com> wrote:
>
> 
> I have cleaned with contact cleaner and paper tape pretty extensively, but
> can always go another round.
>
> I do not think that is a good waveform, but similarly, no idea.
>
> -Eric
>
> On Sat, Aug 5, 2023, 7:23 PM Jeffrey Golas <jeffg at junknet.net> wrote:
>
>> Correct me if Im wrong but could just be "dirty"; as the cam rubs against
>> the switch youre seeing noise like a dirty volume pot.
>>
>> Id use some alcohol and a business card and scrub the contacts (plus Im
>> not sure thats even a terrible signal for a 1940s device. Going machine to
>> machine I dont think that tiny bit of leakage woulda mattered.
>>
>> Again, correct if wrong, Im here learning too.
>>
>> Jeff KC3GJX
>>
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