[Elecraft] K2 / 10 - Freeze Up

[Don Wilhelm]

Chuck,

 From your description of the failure indications, I would say that for 
some reason or another, the microprocessor is simply stopping.

A reset to factory defaults should be done only as a last resort and 
*only* after recording all your menu settings, including your filter 
setup data.  You will need to restore those settings after a reset.

Behavior like that is related to the microprocessor.  Since it is an 
intermittent, one never knows when it is cured.  *I hate 
intermittents!*.  When you try to cathc the problem 'in the act', you 
will touch something that makes it work again, so you can only guess as 
to the source.
For the 'low cost fix', I would recommend doing these steps - in order, 
and after each one, use it for a while to see if the problem has 
disappeared.
1) Remove and reseat the microprocessor to wipe oxides away from the pins.
2) Reflow the solder on the microprocessor socket.  You may want to 
consider removing the existing solder and re-soldering it.
3) Replace the 4 MHz crystal - you might have a balky crystal that just 
quits.
4) Replace the microprocessor socket
5) Replace the microprocessor itself.

If you want a quick cure, replace the crystal, the microprocessor and 
its socket all in one fell swoop - but there is still the off chance 
that there is a bad solder connection somewhere else on the Control 
Board that is causing the failure.

As Geoff pointed out, use of a machine turned pin socket at U6 would be 
a good idea especially if you are in an environment where oxide buildup 
is accelerated.  Machine turned pin sockets provide a gas-tight fit to 
the chip leads where other type sockets do not.

73,
Don W3FPR

Chuck wrote:
> Earlier this summer picked up a very nicely built K2
> to replace the one I had built and foolishly sold. S/N
> is 4715 and the build date is 2/05. Firmware is 2.04P
> 1.09. Installed accessories are K160RX, KAF2, KAT2,
> KI02, KSB2, and KNB2. Additional modifications are the
> W3FPR AF Level Output and Cliffton Laboratories Z10000
> Broadband Buffer Amplifier (used with a SDR-IQ to
> provice external pan-adapter). The K2 has been used in
> the CW mode only.
>
> In the last several weeks have experienced a freeze-up
> almost every time used. Will have completed my side of
> QSO and received without any problem the other party. 
> Upon their turnover discover that I have no transmit. 
>
>
> The display will generally be showing power but,
> sometimes keyer speed and no amount of control
> twisting or button purshing will effect any change. 
> Recycling power will yield "ELE" in the display but,
> otherwise the rig is totally non-functional. 
>
> After several hours, can turn K2 back on and all is
> apparently normal. 
>
> Any ideas would be much appreciated. Have not yet
> reset EEPROM to factory defaults.
>
> 72, Chuck AF4PP  
>
>  
>
>
>       
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