[Elecraft] K2 freeze at startup... need advice

Fri Sep 19 09:58:29 EDT 2008

You are right!! After U6 removed.... RP4 pin 5 and 6 are now at 81k  
ohm!!

U6 must be replaced

Thanks for your help..... But one question remains..... What did  
happen  to U6 ??

Jean-François Ménard

Le 08-09-19 à 09:52, Don Wilhelm <w3fpr at embarqmail.com> a écrit :

> Jean-Francois,
>
> Sounds like you are homing in on the problem.  Try removing the  
> microprocessor and measuring the resistance between RP4 pins 5 and  
> 6.  If it is normal (81K), then you have a bad microprocessor input  
> at pin 30.  If so, replacement of U6 is the only solution I know  
> about.
>
> 73,
> Don W3FPR
>
> Jean-François Ménard wrote:
>> I also found another thing.....
>>
>> Resistance check of Pin 7 and 8 of RP4 on the control board give me  
>> 81K ohm, but PIN 5 and 6 give me 19K ohm... should be 81K ohm too !!!
>>
>> Le 08-09-19 à 09:29, Jean-François Ménard a écrit :
>>
>>> It seems that a resistence check on the control board give me a  
>>> hint..... U6 PIN 29 are inside spec, but PIN 30 give me only 16K  
>>> ohm and should be higher... around 80K ohm to 90k
>>>
>>> The key jack seems to be good, R1 and R2 are OK.
>>>
>>> Re-insert controler on RF board, nothing change
>>>
>>>
>>> Le 08-09-19 à 08:11, Don Wilhelm a écrit :
>>>
>>>> Jean-Francois,
>>>>
>>>> It certainly could be a faulty key jack, but it could be a  
>>>> microprocessor problem too.
>>>> Turn the power down to zero for further testing.
>>>> Then check the voltage at the end of R1 and R2  near the key jack  
>>>> - they are easy to reach if you remove the left side panel.  The  
>>>> voltage should be near 5 volts if there is nothing pulling those  
>>>> inputs down.
>>>> Remember that the DOT line and the PTT line are one and the same  
>>>> on the K2, so if that line is low the problem nay be in the key  
>>>> jack or on the Front Panel board.
>>>>
>>>> Should you find either the DOT or DASH lines near zero volts,  
>>>> turn power off and make resistance checks to find out if there is  
>>>> a short (maybe a solder bridge that has been dormant for a long  
>>>> time).  Those signal lines run direct to the microprocessor, so  
>>>> there is only the jacks, PC traces, and the microprocessor  
>>>> involved.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
>>>>
>>>> Jean-François Ménard wrote:
>>>>> It seems that something let my K2 stuck in TX mode. I removed  
>>>>> all module and put appropriate jumpers (unmod kit). Still in TX  
>>>>> when powered ON. I checked this using my DL2 dummy load with my  
>>>>> multimeter.... I always have output power !!
>>>>>
>>>>> Could it be a defective KEY jack that is jammed? I have nothing  
>>>>> plugged......
>>>>>
>>>>>
>>>>> Le 08-09-18 à 23:33, Don Wilhelm a écrit :
>>>>>
>>>>>> Jean,
>>>>>>
>>>>>> This is strange - the second case of similar behavior reported  
>>>>>> on the reflector today.  Could it be a case of the 'phase of  
>>>>>> the moon'?
>>>>>>
>>>>>> When the K2 is in transmit state, the behavior will be as you  
>>>>>> describe - no buttons operate but the K2 displays the frequency.
>>>>>>
>>>>>> Check to see if your K2 is somehow stuck in transmit.  The  
>>>>>> easiest way is to check the state of the 8R and 8T voltages.   
>>>>>> You can checkby measuring the DC voltage at the anodes of D6  
>>>>>> and D7.  During receive, the voltage at D6 anode should be  
>>>>>> about 8 volts and the voltage at D7 should be near zero volts.   
>>>>>> If the K2 is 'stuck in transmit', those voltages will be  
>>>>>> reversed.
>>>>>>
>>>>>> If your K2 is indeed 'stuck in transmit', try removing the key  
>>>>>> plug and the microphone - if something external is creating  
>>>>>> that transmit condition, it should be OK with those cables  
>>>>>> unplugged.
>>>>>>
>>>>>> 73,
>>>>>> Don W3FPR
>>>>>>
>>>>>> Jean-François Ménard wrote:
>>>>>>>
>>>>>>>
>>>>>>> Hi everybody,
>>>>>>>
>>>>>>> I have my first major trouble since my building experience  
>>>>>>> back in 2004. Now, everytime i power up my K2, I can see  
>>>>>>> ELECRAFT and then the frequency..... but everything is frozen  
>>>>>>> after...... still get the frequency displayed, but no button,  
>>>>>>> no function work. I also tried to reset the K2 to the factory  
>>>>>>> default by holding 4-5-6 buttons..... Got the 201 message then  
>>>>>>> back to the ELECRAFT and the frequency..... but still  
>>>>>>> frozen !!!!
>>>>>>>
>>>>>>> Is it possible the the control board PIC got a static  
>>>>>>> discharge or something like this !?!?!?!
>>>>>>>
>>>>>
>>>>> ============================
>>>>> De Jean-François Ménard / VA2SS
>>>>>
>>>>>
>>>>> --- 
>>>>> --- 
>>>>> ------------------------------------------------------------------
>>>>>
>>>>>
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>>>>>
>>>>>
>>>
>>> ============================
>>> De Jean-François Ménard / VA2SS
>>>
>>>
>>>
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>>
>> ============================
>> De Jean-François Ménard / VA2SS
>>
>>
>>
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>>
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>>