[Elecraft] Help Please KIO2 L4 Burnt Out

[VK1OO]

Hi,

My K2 rig control via a KIO2 stopped.  I discovered that RF sub 
miniature choke L4, 100 micro Henry,  on the main KIO2 board was open 
circuit - no evidence of excessive heat etc.  L4 is in the RS232 ground 
path.  Shorting out L4 restored rig control.  I replaced L4 with a 
larger version (all that I could find locally) but rig control didn't 
work.  I tested the new L4 and it was open circuit, again no evidence of 
excessive heat.  So the question is, what would cause excessive current 
through L4?

I feed the KIO2 via a USB to RS232 converter which plugs into a four 
port USB hub which plugs into a lap top.  This combination has worked OK 
for several years.

Mike VK1OO