[Elecraft] RS-232 Problem

[Bob Whitaker]

Started getting prepared for the CQ WW WPX and discovered that my K-2 would
not communicate with my PC.  I have K-2 with KIO2 and a separate EC-2 with
KPA-100 & KAT-100 installed in it.  Last time I checked, a week or so ago,
everything worked.  No problems communicating with the separate KPA-100 &
KAT-100, so problem has to be with cable or RS-232 circuitry.

 

I've checked the following:

 

1.	Changed ports on PC & control software.-------No Go
2.	Checked connectors & measured continuity on cable-----Found shield
wire on K-2 end loose, resoldered----No Go
3.	Moved KPA-100 back into K-2 & used RS-232 in KPA-100------No Go
4.	Checked voltages on P-4 on Control Board with eight pin cable
disconnected.  Everything normal except for Pin 1 (TXD->1.64 V vs req 5.0) &
Pin 3 (RXD--->.06V vs req 5.0) 
5.	Checked  voltage around MCU RXD & TXD inputs & outputs.   5+V on pin
3 of RP7 & 0.06V on pin 4 of RP7, Also 0.06V on pin 26 (RXD of MCU)
6.	Reset MCU & went through the woes of resetting filters and other
parameters.---Everything works except RS-232.

 

I had already ordered KV-60 upgrade with new MCU and it should be here next
week.  While control board is out should I check C20 & RP7 or could this be
an MCU problem?   

 

Suggestions please.    I worked a little bit of the contest, but without
radio control & readout, it's not fun!

 

Bob

W5RW