Re: KIO2

Posted by Jack Brindle on Nov 09, 2005; 6:54pm
URL: http://elecraft.85.s1.nabble.com/Fw-KIO2-tp383562p383563.html

Might there be a short on the output of U1 pin 5? This is a TX output  
from the driver chip, and even with the negative supply being low, it  
should not be that close to zero, especially with the input at the  
high rail. I would suggest looking for a short across C3,  L2 to  
ground, or even from U1 pin 5 to ground.

L2 may be suspect after you find the short, but it normally fails  
open, which means the connector side is probably OK. It is also  
possible that U1 is problematic, but I would look for the short  
first. When you correct the short, the negative supply should return  
to a more reasonable value since it will have a smaller load to drive.

On Nov 9, 2005, at 8:29 AM, Gilbert J Cross wrote:

>
>
>         Hi fellows. Can't manage to communicate between computer  
> and K2.
> Through control program or HyperTerminal verified that serial port is
> functional on the computer ( Win XP ).
>         Can hear Q1s signal loud.
>         Here are some voltage measurements made this morning.
>         U1-1 14.12 shud be 14
>         U1-2 -1.3mv    "        .1
>         U1-3 13.65     "        14
>         U1-4 -5.4mv    "       .1
>         U1-5 -.017mv   "      -8
>         U1-6 -2.38        "      .1
>         U1-7  13.66      "      14
>         U1-8 -3.13        "      -9
>         U1-9  0            "       0
>         U1-10   0          "      0
>         U1-11  4.89      "       5
>         U1-12   4.98      "      5
>         U1-13  4.89      "       4.5
>         U1-14   0          "       0
>         U1-15   4.89      "      4.5
>         U1-16   4.89      "      5
>         Wonder if getting voltage on pin 8 would to proper level would
> cure the problem?
>         J1-1   0        shud be    0
>             2   -.011       "         -8
>             3   -2.36       "         .1
>             4    6.27        "        4.5
>             5    0             "         0
>             6    5.62        "         5.5
>             7    0             "         0
>             8    14.12       "        14
>             9    8.18         "        8
>         Voltages on J2 are in limits.
>         Any help would be greatly appreciated.
>                         Thanks   Gil   K8EAG
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-Jack Brindle, W6FB
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