[Elecraft] K2 - sudden death

[Don Wilhelm]

Hans,

With the P7 jumper in the EXT position, you are guaranteed to get LO 
BATT warnings, so set it back to the INT position.

Your symptoms sound like you may have a connection in the internal 
battery wiring that is faulty.
OTOH, there could be a fault in the Control Board circuit that feeds the 
Vsense input to the MCU - U3 pins 5, 6, and 7 should all be at 20% of 
the voltage applied to pin 2 of the P7 header.  The same voltage should 
be found at U6 pin 5

If all that checks out, you could have a faulty input pin at U6 pin 5 - 
in which case, replacement of the MCU is the only cure.

Keep in mind that a low supply voltage (or a significant voltage drop in 
the power circuits) will increase the current required. Check with your 
DMM along the power supply rail inside the K2 to see if you can detect 
any significant voltage drops.

73,
Don W3FPR

On 2/1/2015 10:53 AM, Hans Bonnesen wrote:
> K2 - sudden death
> My K2  # 7359 running firmware 2.04 , with internal battery and KAT2 has been behaving wonderfully for more than a year now.
> This morning I switched it on, and heard familiar chatter from other hams -  And after the normal tuning procedure (on approximately 2-3 watt output) I sat down ready for a general SSB rag-chew.
> Suddenly its front panel display said : Low battery, the general hiss of the loudspeaker faded down, the display went dead and the entire K2 went dead.
> Immediate restart wasn’t possible, but after a 10 minutes I could repeat the procedure.
> I then removed the battery and the adjoining cables and placed the K2 battery switch in the battery OFF position, relying now on a small external PS
> The battery seems never the less to  be ok and up to standard.
> At a new attempt the K2 shuts itself of after app. 30 seconds saying : LOW BATTERY (  with no battery connected ????)
> Changed the P7 jumper to ext, and tried once more.
> Still:  LOW BATTERY
> Took another well known 12,5 v gel battery, and checked the amperage when the on button is pressed.
> The K2 is consuming well above 1,5 amps. A loud relay clatter was heard inside the K2.
> Shut it off immediately
> What is suddenly happening ?
>
>
>