From: Anthony Velasco (ecotone_at_mac.com)
Date: Sat Apr 19 2003 - 14:51:54 PDT
Thanks again to all electronics gurus who replied on the zener diode
replacement. I did find replacements via internet orders, but they are
available only in quantities of 2500 or more. I may have found one (the
NTE5018A - 9.1v 0.5w) at a local electronics store, but I cannot find a
cross reference with specifications stating that this is equivalent to
the one PCBman suggests below. One site lists the NTE5018A with another
number: DO-35 - which is also used with the same listing that PCBman
suggests. Is this a category listing that would allow me to consider it
an adequate replacement? Thanks in advance.
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Anthony Velasco, USFWS-Ecologist/ecotoxicologist
ecotone_tv_at_hotmail.com
This Newt's trekking through cactusland and lov'n it!
Managing Sales and Licensing for Newton Software at:
http://www.thisoldnewt.com/~tactilesales/index.html
or http://www.tactile.com - Tactile Systems, Inc.
Contact me via the above E-mail for more information
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
================
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
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