[GreenKeys] Model 14 keyboard adjustment

[Eric Moore]

Thank you, I ended up getting perfect waveforms off the keyboard :)

Now I am battling the printer. Once I have tried and dialed in the
adjustments again I will post what I am seeing.

-Eric

On Wed, Aug 9, 2023, 10:04 PM georgeengeman at aol.com <georgeengeman at aol.com>
wrote:

> Eric--
> If you are using an ordinary ohmmeter to measure the contact resistance of
> your keyboard contacts, be aware that usually these sorts of meters put out
> only a few mA of current in the resistance measurement mode. You need to
> have a sufficient sealing current through these types of contacts. If you
> want to measure the contact resistance, apply your 60 mA current loop
> through the keyboard contacts and measure the voltage across the closed
> contact(s).  Using Ohm's law, deduce what the resistance is. From a
> practical standpoint, your measured voltage should be significantly less
> than 0.5 V
>
> Also, under no circumstances please do not apply any solder to the contact
> surfaces to build up the "thickness" since this will likely permanently
> ruin the contacts and will only last a very short while. In this
> application, solder is worse than useless as a contact material.
>
> I hope that the above helps you in getting your 14 in tip-top shape. You
> are to be admired for embarking on this educational journey.
>
> 73, George W6BN
>
> On Wednesday, August 9, 2023 at 07:22:53 PM PDT, Eric Moore <
> mooreericnyc at gmail.com> wrote:
>
>
> See attached slow-mo video, I hand cranked and cleaned, but resistance is
> still high. I almost want to tin the contacts with solder.
>
> I have been using contact cleaner, perhaps I should move to metal polish?
> I was told it may do a better job removing surface oxides, or maybe I
> should go at it with some fine sandpaper...
>
> -Eric
>
>
> On Sat, Aug 5, 2023, 8:45 PM Mike Douglas <deramp5113 at yahoo.com> wrote:
>
> If this is an R, you should see two high periods of about 22ms within the
> character frame. These high periods occur when those bit position switches
> close, but you’re only getting a brief spike at the instant those switches
> close and open. You need to work on those contacts more. Hand crank the
> keyboard through the bits and verify closed resistance on each bit/switch
> position is an ohm or less.
>
> Mike
>
> > On Aug 5, 2023, at 7:32 PM, Eric Moore <mooreericnyc at gmail.com> wrote:
> > 
> > Hello all!
> >
> > I am working on my 14s keyboard. I have attached a photo and a trace
> from my scope.
> >
> > It looks like it is bouncing? Any ideas how to improve the signal? This
> is R, so 01010
> >
> > Thank you for any help! I have my printer kinda working, I am going to
> use the keyboard to dial in the timing on the governed motor.
> >
> > -Eric
> > <20230805_190327.jpg>
> > <20230721_121647.jpg>
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