Fred,
Only U6 is socketed, all the rest of the Control board ICs are to be
soldered.
If the builder followed instructions, the EEPROM U7 would be soldered
directly.
You are quite correct, sockets sometimes give trouble. Usually removing
U6 from the socket and re-inserting it will wipe the contacts
sufficiently to clear any oxidation that may have occurred during storage.
73,
Don W3FPR
On 4/17/2013 1:03 PM, Fred Townsend wrote:
Don: I do not own a K2 so I am shooting in the dark. On the other hand I
have designed and trouble shot circuits of this kind. Your analysis seems
dead on. Following your lead, are U6 & U7 socketed? If so the symptoms sound
very familiar. It's caused by soldering flux residues migrating to the
contact area of the socket. Time and temperature cycling can make this
happen. If true the sockets may need replacement. If removing and reseating
the chips changes calibration it is a dead giveaway. The chips can be saved
by cleaning in alcohol but cleaning the sockets is almost impossible. Just a
guess.
73
Fred, AE6QL
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