[NTLK] REPOST: Jaggies and voltages

From: Doug Parker (dougparker_at_progressdata.com)
Date: Thu Dec 05 2002 - 13:54:23 EST


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Doug Parker

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>So I did some experimentation (wow, risk-taking). Turns
>out jaggies (at least mine) had to do with a data corruption
>somewhere. I couldn't tell where, but it was something on
>a memory card: no jaggies when the card wasn't in the
>Newton. In fact it could have been the card itself.
>
>So what I did was reinstall the software on a separate card,
>and move the data by re-filing from card to card (it took a
>while: some apps didn't have a 'select all' button). No
>jaggies since then.

Hardware folks, does this make sense? A voltage-sensitive screen being affected by a software reload?

Don't get me wrong--I accept your story, but I'm wondering if coincidence played a role.

I'm leaning toward voltage changes being the culprit--here's my thinking.

Sometimes my screen wigs out briefly with jaggies. When it does I repeat the exact steps to see if I can get jaggies again in the same place. There have been times I'm barely touching the case while I'm writing--barely putting force on it--and it still draws jaggies. But it doesn't seem to do it if I'm not touching the case. (Think about it as completing a circuit--if I don't touch the case, there's no circuit.) If it were pressure on the Newt's case causing the jaggies, how could a super light touch on the case them? It doesn't make sense.

1) As I mentioned above, I get jaggies when I'm barely touching the case. 2) When I switch from battery pack to AC adapter, I often have to realign the stylus. If I'm not mistaken, there's a slight voltage difference between the two power sources. 3) As the charge on my battery pack weakens, the alignment drifts. Think of this as a *really* slow jaggie.

#3 is the most curious to me at the moment.

I can't figure this one out: My jaggies are only along the short width of the screen and not along the long width. Wouldn't you expect jaggies in both directions? If I rotate my screen 90 degrees, my jaggies are still along the short width.

Everyone else, what say ye?

The debris under the edge of the case causing jaggies makes sense for two reasons. 1) physical force of the debris pushing down on the covered edge of the touch-sensitive screen, and 2) if my assumptions are correct the debris can also provides a path for current or static charge to pass from

user --> case --> debris --> screen --> circuitry

I included #1 because I know some people swear that it's a physical force that's causing jaggies, yet it's really #2 on which I'm focusing and which I'm suggesting is a possible alternative cause.

A list member recently wrote that using Deoxit, a liquid that you dab on ends of connectors, cured his jaggies. Deoxit cleans up dirty connections. It provides better circuit completion. Better grounds. Unrelated as it may first seem, bad grounds on a car will light up the reverse lights when you step on the brakes.

I wish I had some sensitive testing equipment at my disposal. I'm sure I could setup a conclusive test to see if varying voltages (through the user) are the cause of jaggies.

Doug Parker

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