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
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