[Elecraft] all I wanted to do was give PSK31 a try, and now I've got real trouble

[Don Wilhelm]

Jef,

Sorry to be the bearer of bad news, but if you dumped 13.5 volts onto 
the 5 volt rail in the K2, it is likely that you have either damaged or 
stressed all the components that operate on the 5 volt rail.
That would be Front Panel U1, U2, U3, and U4.  It is also possible that 
the encoder could be damaged too.  Then on the Control Board, U6, U7 and 
U8 could be damaged, and possibly the 5 volt regulator U5.

These parts are logic components and do not do well when subjected to an 
overvoltage condition.

If you want to do the best repair, I suggest simply replacing all those 
components (except the encoder until it is proven faulty - encoder is an 
expensive part).  Replacing all of the suspect components is likely 
easier than attempting to debug the digital signals to determine which 
ones are possibly damaged.  Even if some of those components work now, 
their life is surely shortened, and may fail later.  The parts cost is 
not excessive, and I recommend replacing them all.

73,
Don W3FPR

KC9GBX at aol.com wrote:
> So I purchased a NUE-PSK modem kit ( I had them do the surface-mount 
> component soldering), and after I had completed my portion of the 
> soldering, things checked out fine.
>  
> I also ordered the cable that connects the modem to my K2, but I was 
> informed that the cable would be shipped separately.  After waiting 
> for nearly a month without receiving the cable, I decided to make my 
> own.  I followed the generic cable-wiring diagram that NUE-PSK 
> provided in the kit assembly manual.
>  
> My crash-scene investigation revealed that I had pumped 13.5 volts 
> from the modem into the K2's microphone jack, pin 6, which is marked 
> on the K2 schematic as a 5 volt line.
>  
> Now, when I push the K2's POWER ON button, I hear an initial relay 
> click, but that's it!!!
> No LCD display, no bar graph, no audio, no band or mode change occurs. 
>  
> I'm hoping that I only fried the 5 volt regulator, U5, on the Control 
> Board, but I'm pessimistic by nature!  I didn't see or smell any 
> smoke.  Any ideas would be most appreciated!
>  
> It's been a great low-power rig for more than 4 years, and I'd sure 
> like to save it!
>  
>                                                                         Here's 
> hoping, and 73, Jef Fox kc9gbx
>
>
>
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