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Dead KPC-3+

Discussion in 'General Technical Questions and Answers' started by K5GT, Jul 12, 2019.

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  1. K5GT

    K5GT Ham Member QRZ Page

    Had an issue 2 weeks back that caused my laptop to die while my KPC-3+ was connected. Plugged in an USB soundcard to see if WinLink with HF worked after testing it on VHF and something shorted and laptop turned off with a loud click.
    Have the laptop back but now it turns out that my TNC is unresponsive. Get no contact with Putty, performed hard reset and saw nothing on the screen.
    Found an old thread that it might be the MC68HC11F1. Looking at the unit it looks like it is seated in a socket.
    Have contacted Kantronics, so waiting on an answer from them as well.
    But is it indeed seated and would this be indeed the source of my problem? Is it 'easy' to replace as the IC is available on eBay for about $18 shipping included.


  2. VE7KNL

    VE7KNL Ham Member QRZ Page

    I don't know if this will help, but I have a Kantronics KAMPlus that was dead. Turned out it was the battery. They aren't happy with a low or dead battery.
  3. K5GT

    K5GT Ham Member QRZ Page

    Thanks will check the battery, to see what state it is in.
    But the thread I read was about disconnecting while not powered off. Because my laptop shut off uncontrolled when I plugged in the USB device I thought that might be a plausible cause.

  4. W9GB

    W9GB Ham Member QRZ Page

    Print Out the Kantronics KPC-3 Plus schematic diagrams and
    parts layout on printed circuit board (PCB).

    Trace the COMPUTER to KPC-3+ circuit lines (5-wire Serial, RxD, TxD, RTS, CTS, GND)
    RS-232-C standard expects +/-12 VDC.

    The micro-processor serial pins operate at TTL voltage levels (5 volt).
    You will find intermediate parts (like 1488 or 14C88) serving as Line Drivers/Voltage Level Converters). These parts can and do fail ... due to External Events (ESD, Operator Errors/Mishandling). Focus on that Area FIRST.

    In my case (that you previous read about), the KPC-3+ TNCs came from First Responders/Law Enforcement - a Box of defective TNCs, for a variety of reasons.
    It is possible that a good processor was harvested (and bad one swapped) — variety of bench techs out there (some never formally trained)
    Tough Field Environments (and Abuse) ... the Service Shops removed defective TNC unit and installed New TNC for Fast turn-around and get the vehicle “back in service”.
    KB0MNM likes this.
  5. K5GT

    K5GT Ham Member QRZ Page

    Thanks, was indeed your post that I was talking about. Meanwhile ordered the 1488 they should arrive in 4 days.
    Meanwhile Kantronics also replied with some things that I could try, but that was more checking voltages and trying a different computer.
    Meanwhile connected it to an other w10 laptop, macbook air and a raspberry pi.
    Kantronics also said that the USB serial would also form some protection if a voltage spike should have traveled over the ground.
    All I know is, it happened when I plugged a USB soundcard into my USB3 port and my Kantronics was still connected to my USB2 port.
    I can use the usb-to-serial to communicate with my rig(s) so that one survived the ordeal


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