[Elecraft] KIO3B USB Surge Suppressor

[hbjr at optilink.us]

Paul...
This is not exactly what you are describing, but it fails open.
https://hifimediy.com/usb-isolator

I've used one at a digipeater site and it took a static hit think - nearby
strike - it protected the TNC and PC.  It was open on every line.

I have used them for ground loops with sound cards.  5000v isolation
(advertised), but it did fail open!

Hank
K4HYJ

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
Behalf Of Paul Christensen
Sent: Friday, June 28, 2019 12:37 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KIO3B USB Surge Suppressor

Looking for input from anyone who has successfully installed a
surge-suppression device on a USB port.  I am in the process of repairing a
KIO3B board after a recent thunderstorm.  

The KIO3B uses an ST Microelectronics USBLC6-2 ESD protection device at the
front end of the K3's USB connector.  The protection device is a SOT chip
that contains five low-capacitance diodes to clamp voltage to acceptable
limits.  

In this case, the diodes have shorted, causing the USB connector to show a
dead short to the PC's USB port, which causes an overload to the PC's USB
power bus.  This has caused all USB ports to disappear in Windows Device
Manager.  The short goes on until I can get to the remote site, sometimes
days or even weeks later.    

Ideally, I would like to find a USB protection device that is designed to
fail open - open as in an open circuit into the USB driver that follows.
That way, I can still find a problem if Windows Device Manager doesn't show
a USB connection while not risking the destruction of the PC's USB power
bus.

Paul, W9AC
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