[Elecraft] Dead K2 After nearby power surge

[KC9QQ]

Don Wilhelm-4 wrote:
> 
> Fred,
> 
> In cases like yours, first step is to connect a dummy load to the K2 
> just in case it is trying to transmit - it is not good to enter transmit 
> state without a load on the PA transistors.  If it is a K2/100, remove 
> the KPA100 and connect the dummy load to the BNC antenna jack on the 
> lower rear panel.
> 
> First thing is to check the state of the 8T and 8R voltage rails. Those 
> are easily checked at the anodes of D6 and D7.  If D7 anode has 8 volts 
> on it while D6 anode has zero volts, then the K2 is in a transmit 
> state.  If both D7 and D6 anodes have 8 volts present, power it only 
> briefly while making further checks lest some components overheat.
> 
> If both 8T and 8R are present, you need to check the state of the RX 
> signal at the gate of control board Q4 as well as the TX signal at the 
> gate of CB Q3 - one should be on (about 5 volts) while the other should 
> be off (near zero volts).  If both of these are on, the microprocessor 
> was zapped with the power surge, but if only one is on, the problem is a 
> shorted Q3 or Q4 on the control board.
> 
> 73,
> Don W3FPR
> 
> Fred Keller wrote:
>> I also just noticed that the power output transistors Q7 and Q8 are 
>> getting warm when the power is on.  I did not say  before but, their 
>> is no display or any other activity on the control board or front panel.
>>
>> Fred, KC9QQ
>>
>>
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> 

Don,

I pulled the control board again to reset the relays and then reinstalled it
to make the measurements on D6 and D7.  When I powered the unit, Elecraft
was again shown and the frequency of 7100 was briefly displayed.  When then
display went out I measured the anodes and cathodes of both d6 and d7 and
measured nearly zero volts on both.

Fred

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