[Elecraft] Re: KX1: power on, no LED readout, then a burning smell

Don Wilhelm w3fpr at earthlink.net
Wed Jul 18 07:50:20 EDT 2007


John,

It would appear that your KX1 is OK except for the burned/vaporized 
board trace.

One possible cause is a short from Q6 to the case when it is assembled. 
  Check for burrs around the countersunk hole in the case and if you do 
not have a nylon screw for securing Q6 to the case/heat-sink, you may 
request one from Elecraft.

To repair the burned trace, scrape out all the burned part and clean the 
solder-masking off the remaining ends of the trace.  Lay in a wire and 
solder the ends.  If you want to make it 'pretty', use a bare wire 
carefully dressed to fit the original path of the board trace and embed 
it in a small amount of epoxy.  A green Sharpie marking pen can color 
the epoxy and make the repair almost invisible.

73,
Don W3FPR

John Shadle wrote:
> One more reply (to myself). I'm looking for some assistance now, I think.
> 
> I checked resistance on the tab of Q6 and get 1k ohm.
> Resistance at pin 1 of U1 is 3.13k ohm.
> Both are supposed to be over 500 ohm, according to p. 58 of the most 
> current manual.
> 
> D7 checks out at .742 one way and .538 the other way, so I think it's 
> alright (forgive my lack of technical jargon; I'm tired).
> 
> I think the only thing I may need to repair is the trace between RP5 and 
> U8.
> 
> So, the question of the evening is...
> 
> Anyone have any idea why this happened? Was it just the fact that more 
> current was flowing through than necessary and my DC wasn't fused at 1A 
> or so? Everything else seems to be in order.
> 
> I just don't want worse damage next time, or to have to do this repair 
> more than once. Thanks for your help, all.
> 
> Off to bed!
> 
> -john W4PAH
> 
> 
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