Elecraft

Question about K2 continuously keying

Classic

List

Threaded

3 messages Options

larse

Question about K2 continuously keying

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.

Thanks in advance for any ideas on where to start.

73’s
Lars
KA4U

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

vk2rq

Re: Question about K2 continuously keying

Sounds like C1 may be short circuit, jack J1 may have failed, or there could be a short somewhere between jack J1, the trace that runs along the RF board from J1 to J8 pin 18, or where the corresponding track on the control board runs to the MCU pin 30. There's not much to go wrong, so I'd suggest first check carefully for shorts/solder bridges, then try removing C1, and if it still fails then replace jack J1.

73,
Matt VK2RQ

> On 4 Jul 2014, at 6:35 am, <[hidden email]> 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.
>
> Thanks in advance for any ideas on where to start.
>
> 73’s
> Lars
> KA4U
>
>
>
>
>
>
>
>
>
> ---
> This email is free from viruses and malware because avast! Antivirus protection is active.
> http://www.avast.com
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm-4

Re: Question about K2 continuously keying

In reply to this post by larse

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, [hidden email] 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.
>
>