[Elecraft] New KX3 reverse voltage smoke

[David Haines]

I'm using the PowerWerx Power supply sold by Elecraft.  I mixed up the 
connections from the binding posts on the back of the power supply then 
plugged the other end into the KX3.  The KX3 was off. Next I turned on 
the power supply.  The wire melted, but I think I was able to disconnect 
the KX3 right away, so it's possible nothing got into the KX3.  Or maybe 
the melting wire broke the connection -- I forgot to do a continuity 
check on the wire.  The KX3 seemed OK, but service said to return it anyway.

David KC1DNY

On 9/5/2020 11:26 AM, Mike Morrow wrote:
> The failure reported by G4JQT and the response of KC1DNY do not reflect what should happen when reverse polarity DC is applied to the KX3 or any other Elecraft rig.  All have that series blocking diode (D6/CMS04 in KX3) that should prevent any significant reverse current flow and certainly should have prevented "smoke" and "melted wire" from developing.  If indeed that is an accurate report, then an explanation from Elecraft should have been requested.
>
> Something else aside from reverse polarity DC is being hidden in the picture being presented so far.
>
> Mike / KK5F
>
> -----Original Message-----
>> From: David Haines <dhaines at bates.edu>
>> Sent: Sep 5, 2020 9:17 AM
>>
>> Don't feel bad Ian.  I reversed the polarity from the power supply, too.
>>    After the smoke cleared and the smell went away, I called Elecraft
>> and after a few questions, service said send in my KX3. They called in a
>> couple days to thank me for sending the melted wire, but why did I send
>> the KX3, which was fine?   They apologized, checked out the KX3,  and
>> gave me a free replacement wire.  Great company!
>>
>> david,  KC1DNY
>>
>> On 9/5/2020 10:06 AM, Ian Liston-Smith wrote:
>>> Well I did it. Inadvertently got the +ve and -ve reversed. Loud buzz from PSU and smoke from KX3.
>>>
>>> Surely D6 in the volts input should just stop everything from working if the polarity is reversed? So I don't understand what has happened.
>>>
>>> I didn't actually switch it on so hopefully it isn't terminal and just enquires a new diode. If it is terminal, I'm really surprised it hasn't any protection.
>>>
>>> Ian, G4JQT
>>> ______________________________________________________________
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