From: Anthony Velasco (ecotone_at_mac.com)
Date: Sat Apr 05 2003 - 06:50:03 PST
Thank you for the in-depth review Mr. PCBman! And thanks to Joel M.
Sciamma, and Martin Joseph for their offline suggestions.=20
Wow! This probably happened the first time the eMate was plugged in for
charging. The eMate was in excellent condition, as if it were hardly
used. Now we know why! Can only guess that the wrong zener slipped into
the bin on the assembly table.=20
Now off to find a place that will sell me less than 2,500 units of the
1SMB5924BT3...more like 2 or 3 would do!
--=20
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
=A0 Anthony Velasco, USFWS-Ecologist/ecotoxicologist
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 mailto:ecotone_tv_at_hotmail.com
This Newt's trekking through cactusland and lov'n it!
Managing Sales and Licensing for Newton Software at:
=A0http://www.thisoldnewt.com/~tactilesales/index.html
or=A0 http://www.tactile.com - Tactile Systems, Inc.
Contact me via the above E-mail for more information
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
=20
Hi Anthony,
I looked at the problem and can see why it burnt up. It is the WRONG
zener.
In the 'bad' unit I can see the motorola logo and 708 on the top.
This is a 1N708. It's a 500mW, 5.6V zener. That's the problem.
The Apple PSU is 7.5V. As soon as the PSU was plugged in, the zener
would conduct. As it is connected across the supply - poof! instant
toast!
The 'good' emate has a 1N713 in it. This is a 9.1V zener. That's much
better. An Apple supply @7.5V nom. won't cause the zener to conduct
under normal conditions.
I suspect the wrong zener was put in the 'bad' unit because it looked
similar. But it's what's under the hood that counts.
The same size package could contain a zener with a voltage range from
2.4V - 200V. It's not enough to just be the same shape.
Anyway, Try 1SMB5924BT3 or equivalent.
Regards,
PCBman
=20
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