The nylon screw is the ultimate answer...The reason the short occurs is that in some instances the tapered head of the screw comes into contact with the sides of the hole in the tab of Q6...Counter sinking the hole in the tab of Q6 works as a temporary measure, but I would not recommend it as a permanent fix...It will get you on the air while you wait for the nylon screw to arrive...
Jerry, wa2dkg
>
Hello all:
I had disassembled my previously operational KX1 (SN854) in anticipation of
adding the KXB3080 option. However I realized that it would be some time
before I could get around to it, and I felt like operating. So I put it
back together, powered it up, and released the smoke. Examination showed
that a short section of V+ PCB trace just after the power switch had
vaporized. PCB traces make excellent fusible links. I measured the
resistance to ground from the far end of the trace. It was 1025 Ohms. By
now I had a pretty good idea what was going on. I repaired the trace, and
measured the same resistance at the power connector. So far so good. I
powered it up outside of the case and all is well. Now I'm real sure what's
going on. I reassembled it into the case, and measured the resistance at
the power connector; 0.4 Ohms. Q6 was shorted to the case. I backed off the
screw for Q6 1/8 of a turn and the short goes away. I examined the plastic
spacer and it does not seem deformed. The insulating pad also seems fine.
I did not torque the screw to 20 foot pounds. I don't know what to do next.
All suggestions appreciated.<
>Thanks,<
>Paul N8NOV<
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