[Elecraft] #3421 MCU problems?

[Daniel Reynolds]

Hi John (and the group),
  
  Nope - I've already checked both dit/dah lines and neither is shorted  to ground. Interestingly - I can insert dahs inbetween the dits, but  that doesn't stop the dits from continuing.
  
  I'm really thinking that a small portion of the MCU may be having  trouble since I looked over the schematic design and I can't see  anything that might buffer the MCU from the dit/mic PTT connection.  Someone please correct me if I am wrong here. It appears that there's a  direct connection between the PTT/DIT connection on the MCU and the  key/mic connections - and if that is the case - the only solution would  be swapping out the MCU.
  
  Thanks for your quick reply, and hopefully someone can confirm my suspicions.
  
  73,
  Daniel AA0NI
  

"John R. Lonigro" <johnlon at sbcglobal.net> wrote:  Dan:
Just got our power back after about 12 hours, due to the same storm (but 
no lightning fortunately).  I'm not the expert on this, but I would say 
to make sure it isn't something simple first, like the dit line being 
shorted out.  I think the key jack is the same design as the headphone 
jack, which has seemed prone to failure.  You can check that with the 
power off and a DMM.  If the line isn't shorted out, wait for one of the 
big guns to reply with further suggestions.

Good luck.  We are expecting another freezing rain episode later this 
evening, but it's above freezing right now and the trees are shedding a 
lot of their ice.  They shedded a lot of their branches last night.

73's,
John AA0VE

Daniel Reynolds wrote:
> Dear Elecrafters,
>
>  I had left my rig on over night, and this mornings ice 'storm' brought  a few strokes of unexpected lightning to the area. Now my K2 (with  KSB2, KNB2, KAT2) is constantly transmitting dits with both mic and key  removed. I'm afraid it might be the MCU. Is this problem 'resetable',  (I can't seem to make any buttons work while it is transmitting - and  it IS transmitting - verified by nearby receiver feeding K2 into dummy  load), OR will I need to replace the MCU?
>
> Thanks,
> Daniel
> AA0NI in icy Oklahoma City
>
>
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