[Elecraft] New KX3 reverse voltage smoke

[Fred Jensen]

K2/100, not KX3, and not a reverse polarity problem but just a 
reminder:  There are two 2-conductor cables in a KPA100 that reach down 
and connect to the main K2 board.  The connectors are identical and the 
cables are long enough that either will reach to either RF board 
connector. If you cross them, you will short the 12V bus on the RF board 
and will likely burn through a trace.

Reporting for a friend, [:=)

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 9/5/2020 10:20 AM, Ian Liston-Smith wrote:
> In my haste to disconnect everything I didn't notice that the antenna was connected, and thus the chassis had a good earth. On close inspection there is a tiny burnt patch around the power supply plug and presumably that's what created the smoke. So I guess the reverse current went through the plug mountings on the board to earth and the reverse diode did its job.
>
> There doesn't seem to be any serious damage to the board at the solder point to the plug, just a black spot that joint took the full force of the shorted current! I gently reheated that spot. Just hope there's not any overheated damage to any internal tracks.
>
> Anyway, seems no obvious harm was done. This KX3 still received and transmits.
>
> I have now replaced most of the original lead with a proper, clearly coloured red/black lead.
>
> 73,
>
> Ian, G4JQT
>