Erratic tuning on K2

[Elecraft mailing list]

One of my K2's has developed a problem where it is (somewhat intermittently) unresponsive to turning the tuning knob.  Turning the knob may or may not, at different times, cause the radio to change frequency.  Pushing on the case/panels and tapping the tuning knob sometimes seem to help, so I am suspicious of the board-mating connectors and solder joints for the encoder. This happens regardless of tuning step size or VFO A/B choice and does not affect the RIT.

A few questions before I tear into it:

Do the encoders ever wear out?

Has this happened to others, and if so, what have the fixes involved?

This K2 has seen a lot of use in the field and mobile as well as at home so humidity- or vibration/shock-induced problems are quite possible.

73,
Steve VE3SMA
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[Don Wilhelm]

Steve,

It is rare to find a faulty encoder.  Those encoders are the optical
type and almost never fail.  I have seen only one failure in the time I
was repairing K2s and I have dealt with over 1000 repairs.

I would first reflow the soldering on the encoder wires and Front panel
U3 as well as P1, RF Board J7 and Control Board P2.  Also reflow Control
Board U6 pins 8 and 16.

73,
Don W3FPR

On 6/10/2019 9:09 AM, Steve Kavanagh via Elecraft wrote:
> One of my K2's has developed a problem where it is (somewhat intermittently) unresponsive to turning the tuning knob.  Turning the knob may or may not, at different times, cause the radio to change frequency.  Pushing on the case/panels and tapping the tuning knob sometimes seem to help, so I am suspicious of the board-mating connectors and solder joints for the encoder. This happens regardless of tuning step size or VFO A/B choice and does not affect the RIT.
>
> A few questions before I tear into it:
>
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[Elecraft mailing list]

 Thanks for pointing out the likely culprits, Don. That's quite a record of repair jobs...it's no wonder you know your way around the K2!

I figured it was unlikely to be the encoder but I thought I'd check just in case.

73,
Steve VE3SMA
     On Monday, June 10, 2019, 10:21:10 a.m. EDT, Don Wilhelm <[hidden email]> wrote:  
 
 Steve,

It is rare to find a faulty encoder.  Those encoders are the optical
type and almost never fail.  I have seen only one failure in the time I
was repairing K2s and I have dealt with over 1000 repairs.

I would first reflow the soldering on the encoder wires and Front panel
U3 as well as P1, RF Board J7 and Control Board P2.  Also reflow Control
Board U6 pins 8 and 16.

73,
Don W3FPR

On 6/10/2019 9:09 AM, Steve Kavanagh via Elecraft wrote:
> One of my K2's has developed a problem where it is (somewhat intermittently) unresponsive to turning the tuning knob.  Turning the knob may or may not, at different times, cause the radio to change frequency.  Pushing on the case/panels and tapping the tuning knob sometimes seem to help, so I am suspicious of the board-mating connectors and solder joints for the encoder. This happens regardless of tuning step size or VFO A/B choice and does not affect the RIT.
>
> A few questions before I tear into it:
>
 
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