K2 Build Problem - No sidetone

[Sean Cavanaugh-4]

Hi all,

I'm building my K2. I've just got to the step where everything gets
assembled and tested for the first time, and when testing the sidetone
I'm getting nothing.

I've set the K2 to edit St L and varied the value from 0 to 255,
checking the voltages on U8. Pin 1 is 0v for all settings, and pin 4 is
also always 0v. The Vdd pin has 5.04v, and all ground pins show
connected to ground. It looks to me like U8 is bad.

Any other ideas?

Thanks es 73,

Sean - VA5LF
______________________________________________________________
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]

Sean,

U8 is seldom faulty.  Check your soldering - refer to the Soldering
tutorial on the Builder's resource page at the Elecraft website if you
have questions.  If suspicious, re-flow the soldering with a hot iron
(750 to 800 deg F).  The solder should flow out to an almost invisible
edge on both the solder pad and the component lead.  If it looks more
like a ball on the solder lead, that is a sure sign that the solder pad
did not receive enough heat.  If there is a lot of solder on the
connection, that can be just as bad because it masks a poor solder
joint.  Wick away the excess and re-solder.  Strive to have only a small
fillet of solder on each solder pad.  Using a small diameter solder
helps to control how much is applied.  I use .015 diameter, but the .020
diameter is usually OK with care.  With larger solder diameters, by the
time the solder flows, you already have too much solder on the connection.

73,
Don W3FPR

Sean Cavanaugh wrote:

> Hi all,
>
> I'm building my K2. I've just got to the step where everything gets
> assembled and tested for the first time, and when testing the sidetone
> I'm getting nothing.
>
> I've set the K2 to edit St L and varied the value from 0 to 255,
> checking the voltages on U8. Pin 1 is 0v for all settings, and pin 4 is
> also always 0v. The Vdd pin has 5.04v, and all ground pins show
> connected to ground. It looks to me like U8 is bad.
>
> Any other ideas?
>
> Thanks es 73,
>
> Sean - VA5LF
> ______________________________________________________________
> 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: 9.0.733 / Virus Database: 271.1.1/2741 - Release Date: 03/12/10 04:42:00
>
>  

______________________________________________________________
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

[Sean Cavanaugh-4]

Thanks Don,

U8 was faulty only in that I missed soldering a pin, and missed it again
while checking it with the lighted magnifier about 5 times. Clearly, I
should be in bed. It's working now.


73,

Sean - VA5LF

On 12/03/2010 11:23 PM, Don Wilhelm wrote:

> Sean,
>
> U8 is seldom faulty. Check your soldering - refer to the Soldering
> tutorial on the Builder's resource page at the Elecraft website if you
> have questions. If suspicious, re-flow the soldering with a hot iron
> (750 to 800 deg F). The solder should flow out to an almost invisible
> edge on both the solder pad and the component lead. If it looks more
> like a ball on the solder lead, that is a sure sign that the solder pad
> did not receive enough heat. If there is a lot of solder on the
> connection, that can be just as bad because it masks a poor solder
> joint. Wick away the excess and re-solder. Strive to have only a small
> fillet of solder on each solder pad. Using a small diameter solder helps
> to control how much is applied. I use .015 diameter, but the .020
> diameter is usually OK with care. With larger solder diameters, by the
> time the solder flows, you already have too much solder on the connection.
>
> 73,
> Don W3FPR
>
> Sean Cavanaugh wrote:
>> Hi all,
>>
>> I'm building my K2. I've just got to the step where everything gets
>> assembled and tested for the first time, and when testing the sidetone
>> I'm getting nothing.
>>
>> I've set the K2 to edit St L and varied the value from 0 to 255,
>> checking the voltages on U8. Pin 1 is 0v for all settings, and pin 4
>> is also always 0v. The Vdd pin has 5.04v, and all ground pins show
>> connected to ground. It looks to me like U8 is bad.
>>
>> Any other ideas?
>>
>> Thanks es 73,
>>
>> Sean - VA5LF
>> ______________________________________________________________
>> 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: 9.0.733 / Virus Database:
>> 271.1.1/2741 - Release Date: 03/12/10 04:42:00
>>

______________________________________________________________
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