[Elecraft] K2 No Menu Problem

[Don Wilhelm]

James,

With 0.1 volts at CB U6 pin 29, I would expect that the K2 may be trying 
to transmit - and that would not allow access to the menu.
So -- KEEP A DUMMY LOAD ATTACHED TO THE ANT JACK until you have the 
situation resolved.

With power off, what is the resistance reading from CB U6 pin 29 to 
ground (measure both on the socket and at the chip pin, they should be 
the same, but check anyway) - with the paddles open (should be a high 
resistance)?  How about when the dash paddle is closed (should be about 
220 ohms)?
If you read a high resistance with the paddles open (or with nothing 
plugged into the key jack) and approximately 220 ohms with the dash 
paddle closed, I would look carefully at the soldering of CB RP4 pins 7 
and 8 - this resistor is the pull-up for the dash line and should bring 
the dash line to 5 volts with the paddle open.  But if those resistance 
readings are not within the realm of sanity, check CB P3 pin 17 and CB 
U6 socket pin 29.  Make certain U6 pin 29 is not bent under the socket 
nor sticking out to the side of the socket.  Also check RF Board J8 pin 
17 and the inboard end of R2.

Let us know where you find something that does not make sense.

73,
Don W3FPR


James Brown wrote:
> K2 #2535 has no menus even though all other functions appear to work.
> I did resistance and voltage checks on control board and found U6 pin
> 29 (/DASH) at .10v instead of the expected 5.0v. The 8v and 5v
> regulators are good. The key jack is not shorted and measures 220ohms
> to ground from P3 pin 17 when the dash circuit is closed. RP4 measures
> 82Kohms from pins 7 to 8. When powered up, RP4 pin 7 measures 5v, but
> pin 8 is at .10v. Pin 8 voltage does not change when U6 is removed
> from socket. Any hints would be appreciated on where to go from here.
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