Elecraft › [K2]

K2 No Menu Problem

Classic

List

Threaded

3 messages Options

James Brown-4

K2 No Menu Problem

K2 #2535 has no menus even though all other functions appear to work.
I did resistance and voltage checks on control board and found U6 pin
29 (/DASH) at .10v instead of the expected 5.0v. The 8v and 5v
regulators are good. The key jack is not shorted and measures 220ohms
to ground from P3 pin 17 when the dash circuit is closed. RP4 measures
82Kohms from pins 7 to 8. When powered up, RP4 pin 7 measures 5v, but
pin 8 is at .10v. Pin 8 voltage does not change when U6 is removed
from socket. Any hints would be appreciated on where to go from here.
______________________________________________________________
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

Don Wilhelm-4

Re: K2 No Menu Problem

James,

With 0.1 volts at CB U6 pin 29, I would expect that the K2 may be trying
to transmit - and that would not allow access to the menu.
So -- KEEP A DUMMY LOAD ATTACHED TO THE ANT JACK until you have the
situation resolved.

With power off, what is the resistance reading from CB U6 pin 29 to
ground (measure both on the socket and at the chip pin, they should be
the same, but check anyway) - with the paddles open (should be a high
resistance)? How about when the dash paddle is closed (should be about
220 ohms)?
If you read a high resistance with the paddles open (or with nothing
plugged into the key jack) and approximately 220 ohms with the dash
paddle closed, I would look carefully at the soldering of CB RP4 pins 7
and 8 - this resistor is the pull-up for the dash line and should bring
the dash line to 5 volts with the paddle open. But if those resistance
readings are not within the realm of sanity, check CB P3 pin 17 and CB
U6 socket pin 29. Make certain U6 pin 29 is not bent under the socket
nor sticking out to the side of the socket. Also check RF Board J8 pin
17 and the inboard end of R2.

Let us know where you find something that does not make sense.

73,
Don W3FPR

James Brown wrote:

> K2 #2535 has no menus even though all other functions appear to work.
> I did resistance and voltage checks on control board and found U6 pin
> 29 (/DASH) at .10v instead of the expected 5.0v. The 8v and 5v
> regulators are good. The key jack is not shorted and measures 220ohms
> to ground from P3 pin 17 when the dash circuit is closed. RP4 measures
> 82Kohms from pins 7 to 8. When powered up, RP4 pin 7 measures 5v, but
> pin 8 is at .10v. Pin 8 voltage does not change when U6 is removed
> from socket. Any hints would be appreciated on where to go from here.
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.325 / Virus Database: 270.12.18/2098 - Release Date: 05/05/09 08:05:00
>
>

______________________________________________________________
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

K5JAZ

Re: K2 No Menu Problem

Don, thanks for your help. Problem solved by replacing R2.

Regards,
Jim Brown, K5JAZ

========================================================
On 5/5/09, Don Wilhelm wrote:

> James,
>
> With 0.1 volts at CB U6 pin 29, I would expect that the K2 may be trying
> to transmit - and that would not allow access to the menu.
> So -- KEEP A DUMMY LOAD ATTACHED TO THE ANT JACK until you have the
> situation resolved.
>
> With power off, what is the resistance reading from CB U6 pin 29 to
> ground (measure both on the socket and at the chip pin, they should be
> the same, but check anyway) - with the paddles open (should be a high
> resistance)? How about when the dash paddle is closed (should be about
> 220 ohms)?
> If you read a high resistance with the paddles open (or with nothing
> plugged into the key jack) and approximately 220 ohms with the dash
> paddle closed, I would look carefully at the soldering of CB RP4 pins 7
> and 8 - this resistor is the pull-up for the dash line and should bring
> the dash line to 5 volts with the paddle open. But if those resistance
> readings are not within the realm of sanity, check CB P3 pin 17 and CB
> U6 socket pin 29. Make certain U6 pin 29 is not bent under the socket
> nor sticking out to the side of the socket. Also check RF Board J8 pin
> 17 and the inboard end of R2.
>
> Let us know where you find something that does not make sense.
>
> 73,
> Don W3FPR
>
>
> James Brown wrote:
>> K2 #2535 has no menus even though all other functions appear to work.
>> I did resistance and voltage checks on control board and found U6 pin
>> 29 (/DASH) at .10v instead of the expected 5.0v. The 8v and 5v
>> regulators are good.