[Elecraft] Second call: K2 broken after KPA100 mod

[Steve Kallal]

Don,

Where is my more complete reply:

The problem appears to be related to something loose aroud the MCU chip on
the Control Board. If I put a lot of pressure on the top of the MCU chip,
the ELECrAFTt message progresses to the frequency readout. This is with the
Control Panel fully mounted and the KAF2 board installed. The connector
cable to the KAT2 and KIO2 are disconnected for now. There are still some
strange things, but at least the unit responds to front panel input.

The pressure I refer to is with my fingers pressing down vertically.
Remember the Control Board is installed vertically. The pressure is along
the top row of pins. I also can use the foam handle of a pair of pliers, in
case any electrical connection is made from my fingers touching the MCU
chip.

So far I've remove the MCU chip, with my wrist grounded, and touched up all
of the solder connections on the socket. I also touched up all of the solder
connections on the pins on that connect to the RF board.

Again my K2 is serial number 2289. It has the mods from the document titled:
"UPGRADING THE ELECRAFT K2 TO REVISION B". Also has mods from documents
titled "ELECRAFT K2 REVISION 2 FIRMWARE" and "Elecraft K2 Keying
Modifications Instructions". Those documents are with the paper included
with this K2.

73,

Steve N6VL

-----Original Message-----
From: Don Wilhelm [mailto:w3fpr at earthlink.net] 
Sent: Friday, July 27, 2007 11:00 AM
To: Steve Kallal
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Second call: K2 broken after KPA100 mod

Steve,

There is no direct relationship between your symptoms and what you intended
to accomplish.  So this is something that inadvertently happened along the
way.

The first thing to do is inspect the control board visually - in most cases
an unsoldered or poorly soldered connection is to blame for behavior like
that.  Move things around a bit to see if you can make it change from
working to not working.  Also check the soldering of the connectors at the
front of the RF Board - they provide a path between the front panel and the
control board.  Be certain the microprocessor (Control Board U6) is properly
seated in its socket and no pins are bent under the chip (you may have to
remove it to check for bent under pins - use good anti-static measures if
you remove it).

If the problem does not reveal itself visually, the next step is to do DC
voltage measurements on the control board and possibly the Front Panel
board. Compare to the DC Voltage chart in the back of the manual.

Since you purchased a used K2, the level may be important - please let us
know the serial number and state of updating that it may have had.
I am sorry I cannot provide a more concrete answer, but it does have nothing
to do with the KPA100 installation at the point where you are now.

73,
Don W3FPR