From: Sonny Hung (sonnyhung_at_gmail.com)
Date: Fri Apr 22 2005 - 04:55:48 PDT
Hi Everyone,
Here is an email I got as a reply for assistance from a Fellow
Newtonian. (Who has a MP120 speed upgrade on line at his website.)
In any case this is his response to my request for assistance.
I hope someone can explain to me what a optoisolator is and looks like...
<FORWARDED MSG>
Lewin A. R. W. Edwards =09
to me
=09 More options=09 7:39 pm (2=BD hours ago)
> The problem this unit has seems to be an issue with all of these
> models due to their age. The vernacular description is that the
> electronics that handle the phone registering that it's hung up is not
> working properly. There are no schematics and we have not been able to
> find one so no one is able to trouble shoot this.
I recall having a very similar problem with a certain breed of modem
(it was a Zoom Telephonics design). As I recall either a transistor or
an optoisolator blew. However your description of a heat-related fault
sounds not entirely consistent with that. I assume there is no relay on
this design, that it uses solid-state hook switching. I'd start by
replacing the optoisolator and if that doesn't work, simply start at
the jack backwards and replace all the semiconductors you can.
I'm afraid I'm just too committed on other projects to take a look at
this in detail, it sounds like a fairly major reverse-engineering
effort, and frankly right now all my out-of-hours time is 150%
allocated.
-- Lewin A.R.W. Edwards Consulting - http://www.zws.com/ Personal - http://www.larwe.com/ Check out my books on embedded engineering! <http://www.amazon.com/exec/obidos/ASIN/0750676094/zws-20/> <http://www.amazon.com/exec/obidos/ASIN/0750677783/zws-20/> <FORWARDED MSG> --=20 God bless, Sonny Hung the Hung Family -- This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries Official Newton FAQ: http://www.chuma.org/newton/faq/ WikiWikiNewt for all kinds of articles: http://tools.unna.org/wikiwikinewt/
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