RE: (ET) Problem with E20

["Kleinbrahm, Bob" <rkleinbrahm firstrepublic com>]

Perry, - thanks for the reply on my problem child.  What kind of diodes
did you use to replace the bad ones on the #4 card?

Bob

-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Perry Cain
Sent: Friday, July 08, 2005 9:16 AM
To: elec-trak cosmos phy tufts edu
Subject: (ET) Problem with E20


I just went through this with an E20 I was working on.  I believe the
problem is bad diodes, bad traces, or a really poor connection on card
#4. This is the card that does not have the varistor.  Take that card
out.  Look at each component and traces very carefully.  VERY carefully!
Some of the
diodes were no good on mine, but they looked ok at first glance.   Also,
the
traces were broken in one little place.  (Reading glasses helped for my
old
eyes)

Look down into the edge connector.  An arc had actually melted one
connector of mine.

Symptoms were exactly the same.  Varistor cooked.  When jumpered, it
cooked the jumper.  (I replaced the varistor, then pulled out Card #4.)
Three speeds only.  I ended up spending a week trying to find an edge
connector that would work, finally I just soldered the wires to the
card.

What the varistor does is protect voltage spikes.  It "captures" them.
At some point, over time, it just cannot take it anymore and cooks.  A
card #4 problem just speeds this up.



_______________________________________________
Elec-trak mailing list
Elec-trak cosmos phy tufts edu
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak



The information transmitted is intended only for the person or entity to 
which it is addressed and may contain confidential and/or privileged 
material. Any review, retransmission, dissemination or other use of, or 
taking of any action in reliance upon, this information by persons or 
entities other than the intended recipient is  prohibited.  If you 
received this in error, please contact the sender and delete the material 
from any computer. 

First Republic Bank and its subsidiaries do not take responsibility for, 
or accept time-sensitive instructions sent by email including orders, 
funds transfer instructions or stop payments on checks. All instructions 
of this nature must be handled by direct communication, not email.

We reserve the right to monitor and review the content of all email 
communications sent or received. Emails sent to or from this address may 
be stored in accordance with regulatory requirements.