[Elecraft] K2 PA and 232 problem

[Don Wilhelm]

Bob,

Other than cutting traces or removing chips, there is no easy way to 
check for such a shorted condition.

I do suspect that the MAX1406 chip (U4) is the one to remove first 
because it is the most likely culprit.  The EL5146 chip (U6) is also on 
the suspect list.

Before desoldering, remove U1 from its socket and see if the 5 volt 
output is restored to normal.

If you do not have adequate desoldering tools, I suggest that you order 
both ICs and a regulator, clip the leads on both ICs and remove the 
leads one at a time - remove the excess solder with solder wick and 
clear the hole with a round toothpick or a stainless steel needle.  The 
replacement ICs are much more inexpensive than the entire board, so it 
is prudent to just replace the ICs wholesale rather than tearing up the 
board in an attempt to preserve the suspect components.

73,
Don W3FPR

Bob G3PJT wrote:
> Hi
>
> My CAT just stopped working and I have found that there appears to be 
> a low resistance on the 5v rail which supplies the PIC / 232 interface 
> chips. This pulls the 5V rail down to 1 v with the result that the PIC 
> and 232 interface chips are not operating and the 78L05 at U3 is 
> rather hot and bothered.
> Before I get the PA board off the heatsink and start desoldering chips 
> has anyone any idea of checks I could do to localise the problem
>
> 73 and thanks for any info
>
> Bob G3PJT
>