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K3 button problem question

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PaulF

K3 button problem question

Seven of my front panel buttons do not function on K3 #757. I also used the
Switch Test to see that they give no scan codes. All other buttons work OK.

Looking at the the schematic for the "Front Panel - Switches" I see these seven
buttons are all connected to the SCANADC0 line into U3. I took off the front
panel and put an ohmmeter from ground to the SCANADC0 line, and it gives a few
ohms. The other lines (SCANADC1-7) show as open.

I looks like either U3, C30, or R27 is bad. Does anyone see any other
possibilities?

I don't relish replacing U3 since it is a 16-pin IC. Maybe some Chip-Quik or
tiny cutters to snip the leads would ease the job.

73,
Paul
K5ESW
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Don Wilhelm-4

Re: K3 button problem question

Paul,

I would suggest an email to [hidden email]. Gary or Dale can
likely give you more information on the most likely cause of this
behavior than anyone else. Unfortunately, it is a weekend right now,
and I know that both do not work on Saturday or Sunday, so wait until
Tuesday to get a response - they have to wade through a lot of email
that builds up over a weekend.

73,
Don W3FPR

73,
Don W3FPR

Paul Ferguson wrote:

> Seven of my front panel buttons do not function on K3 #757. I also used the
> Switch Test to see that they give no scan codes. All other buttons work OK.
>
> Looking at the the schematic for the "Front Panel - Switches" I see these seven
> buttons are all connected to the SCANADC0 line into U3. I took off the front
> panel and put an ohmmeter from ground to the SCANADC0 line, and it gives a few
> ohms. The other lines (SCANADC1-7) show as open.
>
> I looks like either U3, C30, or R27 is bad. Does anyone see any other
> possibilities?
>
> I don't relish replacing U3 since it is a 16-pin IC. Maybe some Chip-Quik or
> tiny cutters to snip the leads would ease the job.
>
> 73,
> Paul
> K5ESW
> ______________________________________________________________
> 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
>
>

______________________________________________________________
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Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Post: mailto:[hidden email]

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Dave Hachadorian

Re: K3 button problem question

In reply to this post by PaulF

Interesting. I also have several buttons that don't work on my
K3:
band up
mode up
ant
shift/lo/norm
rate/lock
NR

The radio is still usable, and I'm waiting for a break in the
contests to send it in for repair.

Dave Hachadorian, K6LL
Yuma, AZ

--------------------------------------------------
From: "Paul Ferguson" <[hidden email]>
Sent: Saturday, April 17, 2010 7:28 PM
To: <[hidden email]>
Subject: [Elecraft] K3 button problem question

> Seven of my front panel buttons do not function on K3 #757. I
> also used the
> Switch Test to see that they give no scan codes. All other
> buttons work OK.
>
> Looking at the the schematic for the "Front Panel - Switches" I
> see these seven
> buttons are all connected to the SCANADC0 line into U3. I took
> off the front
> panel and put an ohmmeter from ground to the SCANADC0 line, and
> it gives a few
> ohms. The other lines (SCANADC1-7) show as open.
>
> I looks like either U3, C30, or R27 is bad. Does anyone see any
> other
> possibilities?
>
> I don't relish replacing U3 since it is a 16-pin IC. Maybe some
> Chip-Quik or
> tiny cutters to snip the leads would ease the job.
>
> 73,
> Paul
> K5ESW
> ______________________________________________________________
> 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

Bob Cunnings NW8L

Re: K3 button problem question

Yep, according to the schematic, these are all associated with the
SCANADC1 line. SPOT is also on that line, do you have trouble with
that button?

A while back I had trouble with some of the buttons on the SCANACD3
line in K3 #495 - Width and AFX in particular, but after a few days
the problem went away suddenly - I have no idea why.

Bob NW8L

On Sat, Apr 17, 2010 at 11:55 PM, Dave Hachadorian <[hidden email]> wrote:

> Interesting. I also have several buttons that don't work on my
> K3:
> band up
> mode up
> ant
> shift/lo/norm
> rate/lock
> NR
>
> The radio is still usable, and I'm waiting for a break in the
> contests to send it in for repair.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
> --------------------------------------------------
> From: "Paul Ferguson" <[hidden email]>
> Sent: Saturday, April 17, 2010 7:28 PM
> To: <[hidden email]>
> Subject: [Elecraft] K3 button problem question
>
>> Seven of my front panel buttons do not function on K3 #757. I
>> also used the
>> Switch Test to see that they give no scan codes. All other
>> buttons work OK.
>>
>> Looking at the the schematic for the "Front Panel - Switches" I
>> see these seven
>> buttons are all connected to the SCANADC0 line into U3. I took
>> off the front
>> panel and put an ohmmeter from ground to the SCANADC0 line, and
>> it gives a few
>> ohms. The other lines (SCANADC1-7) show as open.
>>
>> I looks like either U3, C30, or R27 is bad. Does anyone see any
>> other
>> possibilities?
>>
>> I don't relish replacing U3 since it is a 16-pin IC. Maybe some
>> Chip-Quik or
>> tiny cutters to snip the leads would ease the job.
>>
>> 73,
>> Paul
>> K5ESW
>> ______________________________________________________________
>> 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
>
> ______________________________________________________________
> 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
>

PaulF

Re: K3 button problem question

In reply to this post by PaulF

Thanks to Harry, WE1X, for letting me know of a similar button problem he had.
It is most likely my problem is not caused by the components I suspected, but
rather by the failure of the switch inside the encoder for Speed/Mic.

I was thinking only of the rubber-covered buttons, which cannot result in a
ground out. However the four encoders containing push switches can fail by
putting a ground out to a scan line. There were a few failures on early
encoders, and Elecraft now uses encoders from a different source. I sent my
front panel board back for repair.

73,
Paul
K5ESW