Smoked my K1

[Rick Tavan N6XI]

Hi, guys. I smoked my K1 by plugging in the wrong DC cable. It came from a
35V supply instead of 12V. The radio worked for about 15 seconds, then died
with an odor of burning components; no visible smoke. Realizing what I had
done, I connected it to 12V to troubleshoot. I see only 1Hz pops of (low)
voltage on the 12V line using an analog meter. I hear a weak 1 Hz click from
the speaker, see nothing on the display.  I removed all daughter boards. I
see no visibly burned components. I removed and checked C35 and it still
acts like a capacitor. I measured 4 ohms on the 12V line which seemed low to
me. I removed U5 and saw the same 4 ohms. I reinstalled C35 and U5 (although
I suppose U5 could be the victim/culprit itself) and, per the
troubleshooting suggestions in the manual, measured 5.5K on the 8V line and
670 ohms on the 6V line.  RF-Q7 tab measures 3.5 ohms to ground. No idea
what these resistances should be. Should I just replace U5? Look elsewhere?
Any suggestions would be appreciated.

Thanks & 73,

/Rick N6XI
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[Alexandra Carter]

I'd do my troubleshooting with an ohmmeter FIRST..... 73 de alex NS6Y

On Jul 23, 2006, at 4:58 PM, Rick Tavan N6XI wrote:

> Hi, guys. I smoked my K1 by plugging in the wrong DC cable. It came  
> from a
> 35V supply instead of 12V. The radio worked for about 15 seconds,  
> then died
> with an odor of burning components; no visible smoke. Realizing  
> what I had
> done, I connected it to 12V to troubleshoot. I see only 1Hz pops of  
> (low)
> voltage on the 12V line using an analog meter. I hear a weak 1 Hz  
> click from
> the speaker, see nothing on the display.  I removed all daughter  
> boards. I
> see no visibly burned components. I removed and checked C35 and it  
> still
> acts like a capacitor. I measured 4 ohms on the 12V line which  
> seemed low to
> me. I removed U5 and saw the same 4 ohms. I reinstalled C35 and U5  
> (although
> I suppose U5 could be the victim/culprit itself) and, per the
> troubleshooting suggestions in the manual, measured 5.5K on the 8V  
> line and
> 670 ohms on the 6V line.  RF-Q7 tab measures 3.5 ohms to ground. No  
> idea
> what these resistances should be. Should I just replace U5? Look  
> elsewhere?
> Any suggestions would be appreciated.
>
> Thanks & 73,
>
> /Rick N6XI
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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