Dr Newton,
Here are my replies to your recent email:
> In NewtonTalk V1 # 11, David Humphreys made the following
> comments.....
>
>
> >As I follow the threads on this subject, it seems that
> people are generally
> >experiencing this after an upgrade or screen replacement.
>
> >The board is certainly removed for screen replacement and
> may or may not be
> >removed for memory upgrade (depends who does it).
>
>
> Gee, thanks David for insinuating that the MP2000 Upgrade (
> I'm the only US
> source )
> causes the "jaggies problem".
'Generally' means in most cases (that have been reported here). It DOES NOT
imply that your upgrade has caused it. In actual fact, although you are
probably
the only source that does this as a service, there are some people who have
done
the upgrades themselves. (I am one of them)
>
> Apple hasn't provided the upgrade in 2 years so you must be
> talking about
> me.
No I wasn't See above.
> In the future, get your facts straight before broadcasting
> misinformation.
I am not in the habit of 'broadcasting misinformation' as you put it. The
facts are that:
1/ In a number of cases, people have experienced this after some disturbance
to the unit. (Although by no means everybody)
2/ Pressure on different parts of the screen (e.g. business card trick)
has, in a
number of cases, fixed the problem, indicating to me that the problem is
probably
Hardware related. A software problem, although possible, would manifest
itself in more units than are being reported to this forum.
> If you've spent any time reading the comments of people
> experiencing this
> especially on discussion boards ), you'll see that it has
> several possible
> causes. Upgrading the D-Ram is NOT one of them.
I understand your need to defend your position.
I am sure you take the utmost care when doing upgrades. Let me publicly
thank you for you service to the Newton community.
I think the caveat 'depends who does it' covers this.
> Possible Causes :
>
> 1. The Touchscreen "delaminates" in areas over time due to
> regular use.
> 2. Slight warping of the bezel edges puts light pressure on
> touchscreen
> edges.
> 3. Corrupted system "soups" have also been reported to cause it.
> 4. Grit or dirt particles wedged between the touchscreen and
> bezel exerting
> pressure on the touchscreen.
Three of your four 'possible causes' are hardware and one is software. I
don't hold you responsible for any of this but, just based on your data
given, 75% of the time it could be hardware related. ;-)
> >The flex connection, as has been observed, is a compression
> type and relies
> on
> >the intimate contact of two surfaces. Oxidation of the
> contacts on the flex
> >is a real possibility.(Don't do repairs while eating Doritos;-))
The 'Doritos' comment is for purely comic illustrative purposes only
regarding contaminants.
>
>
> The PCB pads to connect the touchscreen are gold plated. Gold does not
> oxidize.
Well, with 25 yrs in the PCB industry, I can tell you that this is not
exactly true.
It IS true to say that it is tarnish resistant,(hence its use in this
application) That does not mean that it can't or won't tarnish. It can form
sulfite-gold complexes.
> The "tail" contacts on the touchscreen are tin.
> Though tin can oxidize on the surface a little,
> cleaning away what little is there has no effect from my experience.
So you have tried it? Then, can one infer from your comment that you
thought, at least at one point, that this connection may be causing a
problem?
>
> Note :
>
> When Apple was performing upgrades, they flooded the boards
> with solvent.
This would presuppose that the board wasn't removed for the upgrade.
Is it your contention that Apples' manufacturing and repair practices were
suspect?
> There is a possibility ( in my opinion ) that some
> contamination could have
> settled in the touchscreen related region of the board. This is only
> speculation though. I would guess that humidity increases
> might reactivate
> the flux that remained and cause problems. Over the years I
> have seen some
> of the water soluble fluxes cause severe impedance problems
> with certain
> types of circuits.
I find it hard to believe that Apple would allow such a practice to happen.
> When I upgrade MP2000's, I do not touch anything outside the
> D-RAM area.
O.K.
So do you remove the board for this upgrade or not?
> In several hundred upgrades over the course of 2 years, I
> have NEVER had a
> customer comment that his/her unit now started exhibiting
> "jaggies" after
> the upgrade.
And I, did NOT insinuate that you, per-se, were the cause.
As I have stated earlier, I am sure you are doing a fine job. I am simply
stating
an opinion based on the information that I have.
Keep up the good work.
Regards,
David Humphreys
PCB Designer
Honeywell Inc.
mailto:david.humphreys@honeywell.com
******************************************
This NewtonTalk Message brought to you by:
EVOTE.COM, the ESPN of Politics on the
Internet. Visit EVOTE.COM for all the latest
news on Campaign 2000!
Visit http://www.evote.com today!
******************************************
Need Subscribe/Unsubscribe Info?
visit http://www.planetnewton.com
******************************************
This archive was generated by hypermail 2b29 : Wed May 03 2000 - 09:41:15 EDT