IC-7100 Clock Failure

Discussion in 'Radio Circuits, Repair & Performance' started by KM4KLB, Jan 2, 2019.

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  1. KM4KLB

    KM4KLB XML Subscriber QRZ Page


    I have a similar issue as the reported IC-7300 Clock Battery Failure.

    I have have had my IC-7100 for over three years. I mainly use my radio on the weekends and do not have it powered up continuously. I only power it when I use it. I recently took on a large project that limited my time on air and I have gone a few months without being able to use my IC-7100.

    Now, if I leave the IC-7100 powered off at the main power supply for more than a day, the date clears and the clock resets back to 00:00. As long as I leave the main power on, the clock remains corect. I do not notice a difference in any of the settings other than the clock.

    I contacted ICOM about the issue and even asked specifically if the problem could be caused by a dead clock battery. I was informed that the IC-7100 does not have an internal battery and that I would need to have the system serviced to repair the problem.

    Are there any ideas on a solution or a confirmation that the IC-7100 does/does not have a clock battery? It's hard to believe that a clock could keep time without some sort of power.

  2. AA5CT

    AA5CT Ham Member QRZ Page

    Sounds like they maybe use what's called a "supercap" for the power source ... and it's gone bad, or something is sapping current from it.
  3. G3ZBP

    G3ZBP Ham Member QRZ Page

    NOTE: The backup battery for the internal clock
    The IC-7100 has a rechargeable Lithium battery to backup the internal clock.
    If you connect the transceiver to a power source, the battery is charged and it keeps the correct clock setting. How-
    ever, if you do not connect the transceiver to a power source for a long period of time, the battery will discharge. In
    that case, the transceiver resets the internal clock.
    If you do not use the transceiver for a long period, we recommend that you connect the transceiver to a power
    source at least every three months. The charging period is two days, regardless of the whether the transceiver’s
    power is ON or OFF.

    From Icom IC-7100 workshop manual.

    K4AGO likes this.
  4. KM4KLB

    KM4KLB XML Subscriber QRZ Page

    Thanks Martin. I have left the system powered for up to one day in case there was a rechargeable battery with limited success (the time only stays for a few days). I will try leaving it powered for at least two days to see if it will fully charge.

  5. KM4KLB

    KM4KLB XML Subscriber QRZ Page

    Attempt #1 failed. I kept the unit powered for 4 days and the clock battery did not last a week. I am giving it another try to see if the charge will hold. If it doesn't, can I change the battery?

  6. W9GB

    W9GB Ham Member QRZ Page

    The Icom IC-7100 is a 21st century radio, hence the majority of its construction uses Surface Mount (SMT) components. While the Part is cheap (in price), it requires skills and tools like that of a jeweler (handling small parts and light touch) in removal and soldering of replacement.
    The IC-7100 radio has BOTH a Seiko Lithium Battery AND an Elna SuperCapacitor (DX-5R5H334U)

    ICOM IC-7100 Service Manual
    PARTS LIST, Section 6
    Page 5-14 and Page 6-1
    Reference Number: BT6201, Order number: 3020000390
    OEM supplier/part: Seiko ML414HIV01E

    Digi-Key # 728-1052-1-ND : $1.81 each.
    ML414H Datasheet
    https://media.digikey.com/PDF/Data Sheets/Seiko Instruments PDFs/ML414H_E.pdf
    Last edited: Jan 16, 2019
    N7IQZ likes this.
  7. KM4KLB

    KM4KLB XML Subscriber QRZ Page

    Thanks for providing the information. It has allowed me to review the situation and determine that the replacing the battery myself may require tools that I do not have and it would not be profitable for me to get just for this use. I think it is time to take the unit to the shop.

    The second attempt at charging the battery for 5 days has failed.

    Thanks for all of the information and advice! At least I can make an informed decision now.

  8. IW1AU

    IW1AU Ham Member QRZ Page

    Why not to repalce with a typical button battery for clocks? With 100k in series should be not damaged?
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    If you do that you should use a diode, Not a resistor.

    Then you have 1 diode voltage drop to deal with.

    No reason not to use the correct rechargeable battery.
  10. IW1AU

    IW1AU Ham Member QRZ Page

    In principle I agree, but because the recharge current pass throught 100k I don't expect issues even a diode is not inserted...
    I did a screenshot of the original IC-7100 diagram...

    Attached Files:

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