[Elecraft] KAT 2 Woes

[Tom Field]

I was reaching the final stages of installing the KAT2 to my K2. When I
added power, I heard some sizzling and smelled smoke, This didn't happen
with previous power up testing and the build and testing seemed to go
without problems. I noticed that U1 was warm.
Careful inspection showed that when I plugged J8 into the Control Board of
the k2, I inadvertently shifted the plug up one space, causing the wrong
signals/voltage to go down the wire. Corrected that and proceeded to test.
The menu for the ATU appeared without problems and the Ant1/2 cycled on and
off appropriately. When Checking voltage on U4, during TUNE at 5 , I only
get 0.3 to 0.4 volts.
The manual suggests that there is a problem with the build of the SWR
bridge. Will check that, but my question is did I fry U1 and could that be
the cause of what I see?

Tom Field
KI6NRD
K2 # 7432

Note: The K2 was working fine as a QRP CW machine prior  to this.