[Elecraft] More Troubleshooting Help

[Roy Vickers]

Ok, the ongoing saga of the "blown K2/plugged wrong serial cable" continues.
I replaced U3 and I now have my 5v back. FYI, I've replaced U1, U4 & U3 on
the KPA/100 and the MCU on the K2 so far. My next path is to find why the K2
doesn't know the KPA/100 is a attached, same symptoms whether 12v is applied
to the K2 or the KPA/100. Here's my symptoms:
1. All voltages ok except the following:
2. U1 p7 0v
3. U1 p9 & p10 .13v
4. U1 p11 0v
5. U1 p18 5.04v
6. U1 p27 .05v
7. U4 p10 5.14v
8. fan runs all the time
9. a lot of noise coming from speaker as if I had a noise generator
connected
It appears to me the most obvious symptoms are the incorrect voltages at U1
p9,10,11. Could Q12 be the culprit? Also how does the KPA100 signal the K2
it is attached?
Thanks guys, I couldn't do without you...
Roy KF5YU