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Re: K2 Build #7552

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Kev Schache

Re: K2 Build #7552

Many thanks to Don and others who responded.
The problem has been fixed, I found a suspect dry joint on the PTT/ATT
switch.
I also checked the new encoder which appeared ok but I did insert a very
thin piece of insulation between the new encoder and the control board
to make sure.

All tests now appear ok UNTIL I re-insert and tighten the two holding
screws in the Control Board. When these are tightened, the control board
is pulled about 1/8th inch toward front panel, probably stressing both
boards, causing the display to be erratic (ELICRAFT instead of ELECRAFT
for example), and erratic other test results. Stressing the boards may
be causing movement in sockets where they are used.

Does it matter if I leave those two screws out?
Another option would be to put in longer screws and not tighten them so
much, or perhaps a better suggestion maybe to increase the spacer length
marginally, so that there is no stressing.

73,
Kev VK5KS

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vk2rq

Re: K2 Build #7552

Te kit should fit together without needing to use longer screws, etc.. If it doesn't, then it indicates you may have done something wrong.

Are the PCB headers sitting properly flush wi the board, or are they sticking up a bit, possibly causing misalignment? Are you sure you used the right size standoffs? If you used ones that are too short, then this could put stress on the board when you tighten the screws.

If all the connectors and securing hardware is correctly installed, then erratic behaviour could be an indication of further dry joints. It is worth to inspect all the joints with a magnifying glass and a strong light, although poor joints are not always obvious to the eye.

73,
Matt VK2RQ

> On 29 Sep 2014, at 12:14 pm, Kevin Schache <[hidden email]> wrote:
>
>
> Many thanks to Don and others who responded.
> The problem has been fixed, I found a suspect dry joint on the PTT/ATT switch.
> I also checked the new encoder which appeared ok but I did insert a very thin piece of insulation between the new encoder and the control board to make sure.
>
> All tests now appear ok UNTIL I re-insert and tighten the two holding screws in the Control Board. When these are tightened, the control board is pulled about 1/8th inch toward front panel, probably stressing both boards, causing the display to be erratic (ELICRAFT instead of ELECRAFT for example), and erratic other test results. Stressing the boards may be causing movement in sockets where they are used.
>
> Does it matter if I leave those two screws out?
> Another option would be to put in longer screws and not tighten them so much, or perhaps a better suggestion maybe to increase the spacer length marginally, so that there is no stressing.
>
> 73,
> Kev VK5KS
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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Don Wilhelm-4

Re: K2 Build #7552

In reply to this post by Kev Schache

Kevin,

That is "telling" that you have not truly flush trimmed the lead on the
encoder board and the area of the control board where it makes potential
contact. There is not a lot of space for error there.

Flush trimmed means really flush with the board thickness. Solder that
protrudes from the board surface is too much.

you may do well by putting an insulating substance such as a layer of
electrical tape over the encoder board after flush trimming it.

73,
Don W3FPR

On 9/28/2014 10:14 PM, Kevin Schache wrote:

>
> Many thanks to Don and others who responded.
> The problem has been fixed, I found a suspect dry joint on the PTT/ATT
> switch.
> I also checked the new encoder which appeared ok but I did insert a
> very thin piece of insulation between the new encoder and the control
> board to make sure.
>
> All tests now appear ok UNTIL I re-insert and tighten the two holding
> screws in the Control Board. When these are tightened, the control
> board is pulled about 1/8th inch toward front panel, probably
> stressing both boards, causing the display to be erratic (ELICRAFT
> instead of ELECRAFT for example), and erratic other test results.
> Stressing the boards may be causing movement in sockets where they are
> used.
>
> Does it matter if I leave those two screws out?
> Another option would be to put in longer screws and not tighten them
> so much, or perhaps a better suggestion maybe to increase the spacer
> length marginally, so that there is no stressing.
>

Vic Rosenthal

Re: K2 Build #7552

In reply to this post by Kev Schache

I think you should go over all the solder joints on the control board.
Just heat them up and apply a tiny bit of solder. Wait till it flows. It
is not a good solution to leave out the screws, because oxidation may
ultimately make the bad solder joints fail even when the board is not
stressed.

If you don't have a good temperature-controlled soldering station, it's
worth considering.

On 9/29/2014 05:14, Kevin Schache wrote:

>
> Many thanks to Don and others who responded.
> The problem has been fixed, I found a suspect dry joint on the PTT/ATT
> switch.
> I also checked the new encoder which appeared ok but I did insert a very
> thin piece of insulation between the new encoder and the control board
> to make sure.
>
> All tests now appear ok UNTIL I re-insert and tighten the two holding
> screws in the Control Board. When these are tightened, the control board
> is pulled about 1/8th inch toward front panel, probably stressing both
> boards, causing the display to be erratic (ELICRAFT instead of ELECRAFT
> for example), and erratic other test results. Stressing the boards may
> be causing movement in sockets where they are used.
>
> Does it matter if I leave those two screws out?
> Another option would be to put in longer screws and not tighten them so
> much, or perhaps a better suggestion maybe to increase the spacer length
> marginally, so that there is no stressing.
>
> 73,
> Kev VK5KS

--
73,
Vic, K2VCO/4X6GP
Rehovot, Israel
http://www.qsl.net/k2vco/
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Kev Schache

Re: K2 Build #7552

In reply to this post by Don Wilhelm-4

Don,

YAAAYYY!!!
The answer turned out to be very simple. I loosened all the chassis
screws in the assembly to date. which gave enough movement in the boards
particularly the RF board, to allow the screws fixing the Control Board
to be tightened easily. I then tightened all the remaining chassis
screws again and everything tests ok.

Yes, I did check all boards again for any suspect joints.

Thanks to Don, Matt, Vic, and all..
On with the next stage !!

73,
Kev VK5KS

On 29/09/2014 1:51 PM, Don Wilhelm wrote:

> Kevin,
>
> That is "telling" that you have not truly flush trimmed the lead on
> the encoder board and the area of the control board where it makes
> potential contact. There is not a lot of space for error there.
>
> Flush trimmed means really flush with the board thickness. Solder
> that protrudes from the board surface is too much.
>
> you may do well by putting an insulating substance such as a layer of
> electrical tape over the encoder board after flush trimming it.
>
> 73,
> Don W3FPR
>
>
> On 9/28/2014 10:14 PM, Kevin Schache wrote:
>>
>> Many thanks to Don and others who responded.
>> The problem has been fixed, I found a suspect dry joint on the
>> PTT/ATT switch.
>> I also checked the new encoder which appeared ok but I did insert a
>> very thin piece of insulation between the new encoder and the control
>> board to make sure.
>>
>> All tests now appear ok UNTIL I re-insert and tighten the two holding
>> screws in the Control Board. When these are tightened, the control
>> board is pulled about 1/8th inch toward front panel, probably
>> stressing both boards, causing the display to be erratic (ELICRAFT
>> instead of ELECRAFT for example), and erratic other test results.
>> Stressing the boards may be causing movement in sockets where they
>> are used.
>>
>> Does it matter if I leave those two screws out?
>> Another option would be to put in longer screws and not tighten them
>> so much, or perhaps a better suggestion maybe to increase the spacer
>> length marginally, so that there is no stressing.
>>
>
>
>