Reversed connections from KIO2 to KAT100

[Gil WA5YKK]

   I've hit a wall with one of the strangest situations, having simply
not taken time to recheck all my connections on the DB9 connector from
the KIO2 to the KAT100. I had the KIO2 pins reversed in color order,
from 6 to 9, plugged it in to smoke test the circuit to the KAT100, and
got "zero" results. When I checked with Gary, I was informed that some
seven parts, on three boards, have to be replaced, and I'm wondering if
anyone else has had this same miscue, can give me hints about what other
problems have been caused by the miswiring? I have to do a lot of major
surgery on the boards, and might have to realign the Control Board. Any
hints and kinks beyond the missives I've already gotten will be
appreciated. Murphy's Law strikes again, right at a critical time!!

73's
Gil WA5YKK
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[Stuart Rohre]

Gil, a good technique is to make a copy of the schematic, maybe even with
magnification, to see more easily where the leads of the connector go, (to
which components).  Then, with a colored pencil, trace out each pin to what
it is connected to (component), and evaluate what the reversed voltage
situation was, and then, if it could have failed the component connected to
the pin.

For example, consider that a capacitor might be connected to the pin you are
tracing.  If it is a ceramic disk, it is not polarity sensitive and likely
would also be rated at a voltage high enough to withstand anything
mis-connected to it.

But, if the capacitor had been electrolytic, and the wiring problem placed a
negative voltage on the positive side of  the capacitor, you likely would
want to change it, in case it has been compromised or stressed, even if it
is not showing short or open at this time.   In a like manner, you can find
what active components, (transistors or ICs) might need to be swapped if
they endured reversed voltages, or overvoltage, such as an input being
connected to a DC bus voltage.

GL and 73,
Stuart
K5KVH


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[Don Wilhelm-3]

Gil,

Actually things may not be all that bad and you may find that the only
components damaged are the KPA100 firmware chip and KPA100 U6.

However, you should be prepared with all the parts that Gary listed just
in case.

Reversing the color sequence would have placed 12 volts on the KPA100
VRFDET line which goes to U6 and would likely cause its early demise.
The same combination would have placed the KPA100 12CTRL line onto the
K2 VRFDET line, but there is no source in the KPA100 for the 12CTRL line
and the K2 microprocessor may have survived.
Similarly the K2 8R line would have been placed onto the KPA100 AUXBUS
line, and surely would have killed the KPA100 firmware chip, but going
the other way and placing the 8R line from the KPA100 onto the K2 auxbus
line may have caused no damage since there is no source in the KPA100
for voltage on the 8R line.

Does the base K2 still work?  If so, you may have been fortunate.

73,
Don W3FPR

Gil Gibbs wrote:

>   I've hit a wall with one of the strangest situations, having simply
> not taken time to recheck all my connections on the DB9 connector from
> the KIO2 to the KAT100. I had the KIO2 pins reversed in color order,
> from 6 to 9, plugged it in to smoke test the circuit to the KAT100, and
> got "zero" results. When I checked with Gary, I was informed that some
> seven parts, on three boards, have to be replaced, and I'm wondering if
> anyone else has had this same miscue, can give me hints about what other
> problems have been caused by the miswiring? I have to do a lot of major
> surgery on the boards, and might have to realign the Control Board. Any
> hints and kinks beyond the missives I've already gotten will be
> appreciated. Murphy's Law strikes again, right at a critical time!!

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