[Elecraft] Question about K2 continuously keying

[Don Wilhelm]

Lars,

First, turn the power all the way down and attach a dummy load to 
protect your K2.
It will have to be a process of elimination to determine where the 
problem source may be.

You are looking for a short on the dot line.  Keep the K2 in CW mode.

First, remove the KSB2 board (no jumpers required for this test, you 
will still hear sidetone), then see if the problem continues.  If it 
stops, the problem is on the KSB2 board - check resistance to ground at 
P1 pin 4 - if close to zero, remove the KSB2 firmware.  If the 
resistance increases, replace the firmware chip.

If the problem continues with the KSB2 removed, power off, then check 
the resistance to ground at both ends of R1 (you may want to remove the 
left side panel for easier access to R1).
Is there a lower resistance on the side toward the key jack?  If so, 
replace the key jack.
If the resistance is lower on the side of R1 away from the key jack, try 
removing the control board and see if the resistance goes up. If it 
does, you may have a shorted MCU pin - remove the MCU and put the 
Control board back in.  If the resistance stays high, replace the MCU 
firmware IC.

Now if  the resistance stayed low with the Control Panel removed, you 
have one more step to do - remove the Front Panel and check the 
resistance again.  If it is now high (greater than 1k), you have a 
problem on the Front Panel.  Check for solder bridges or other things 
that may have bridged a connection - look especially at the microphone 
configuration header and the mic jack (the PTT line is the same as the 
DOT line).

73,
Don W3FPR


On 7/3/2014 4:35 PM, larse at ardmore.net wrote:
> I’m hoping for some advice on where to start troubleshooting a problem that started this afternoon.
>
> Before I start digging into the K2 perhaps someone on the list has had a similar problem and can help save some time in troubleshooting and repair.
>
> Here is what I’m experiencing.
>
> While listening to cw on my K2 (s/n 2711, 15 W) the unit suddenly started keying dots.  I shut the unit down and removed the key but when I powered the unit on the problem remained the same.
> I shut the K2 off, removed the microphone so there was no microphone or key attached, turned the unit back on and the problem is still there.
>
>