[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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