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Icom IC-745 Ram Board programming

Discussion in 'Radio Circuits, Repair & Performance' started by KC4UMO, Jan 3, 2018.

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  1. KC4UMO

    KC4UMO Ham Member QRZ Page

    Since there are so many of these vintage rigs on the market I thought I would share this here.
    The 745 is a great old rig and I love mine. As we all know there is a problem in the design that can cause the radio to become inoperable. That is the battery on the ram board. This battery not only holds user memory information but it also holds factory programming. This is called volatile memory. And when the battery dies the radio becomes a brick. Back years ago you send the rig or board back to Icom and they would replace the battery and reprogram the board. Icom no longer supports this.

    The good thing today is you can now purchase nonvolatile memory boards. Both are great and work well and you do not have to worry about replacing the battery to keep from bricking the radio. The batter only stores user information.
    The PIEXX board:

    Roberto Nardo, IK2RND board:

    Later down the road a couple of gentlemen developed software and a programmer to load the memory back to the ram board. This was a DOS based program.

    So what about originality? Keeping the radio as stock as possible for the nostalgia crowd.
    A few weeks back I decided to try and reprogram the boards myself.
    After spending 2 weeks using the N2CBU program and programmer it ended in a complete failure.

    I tried this on a 286 running Windows 3.1 and a 386 running Windows 98.
    The parallel port will just not let the program see the programmer.

    The next idea came from a guy over at the EEVBlog forum where we have a thread running there on programming these boards.

    Someone suggested programming via Arduino. Until this past week I have never put my hands on one. So knew nothing about them. I do have one now and working through it. Another guy recommended programming them with a more modern programmer. But the bin file had to be split. He uploaded a board design to build an adaptor and a zip file with modified files for the 745, 751 and the Icom receiver.

    The programmer arrived today, I built the adaptor board in a crude fashion. The programmer is the cheap Mini Pro TL866. I used the Dallas DS1220 chip setting. We are now able to read and write to the ram board.
    I will be putting together a PDF on the unit and posting it on my website for download.

    Here is part 2 of the video showing the adaptor board and programming a dead board.
    Much more to come on this soon.

    WD4ANA and 2E0TZX like this.
  2. KA5IPF

    KA5IPF Ham Member QRZ Page

    I'm glad someone figured it out. I gave up years ago and just used Roberto's boards or Chris's (Piexx).
    KC4UMO and 2E0TZX like this.
  3. KC4UMO

    KC4UMO Ham Member QRZ Page

    Hi Clif,
    I tried this many years ago myself and gave up. But this time I was determined to find a way to do it. The team came through. What really surprised me is after all was said and done the actual programming time is under 2 seconds.

    Again, nothing at all wrong with the new supplied boards that you mentioned. I have installed quite a few of them. And they work fine.
    Just wanted a different alternative for nostalgia.
    Thanks for the comment.
    2E0TZX likes this.

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