Sources for FT-747GX Battery Replacement?

Discussion in 'Radio Circuits, Repair & Performance' started by AC0UK, Jun 3, 2013.

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  1. AC0UK

    AC0UK XML Subscriber

    Hi all,

    I need to replace the memory-backup lithium battery that is soldered onto the display board inside the FT-747GX. Initial google searches haven't turned up anything obvious.

    I am comfortable with the de-soldering and resoldering process, but I have a question about finding the replacement battery. I'm looking at US sources FWIW.

    What is a modern equivalent part number? Is there a specific kind of battery or can I just use an off-the-shelf battery like a CR2032?

    Second question is on mounting...

    It looks like the existing battery is similar to a readily available coin cell but it had pre-attached mounting tabs that were used to attached it to the radio. Do those come off so I can reuse them? I bet the replacement Yaesu battery probably came with those tabs. Do I need to make my own replacements? Or can I buy something off the shelf? Any sources for such?

    If anyone has prior success replacing this battery please let me know.

    73's, Willie / AC0UK
     
  2. K9YLI

    K9YLI Ham Member

    www.batteriesamerica.com middleton wisc.
    they have about every type of button battery there is.
    just get the type off the battery and order. Catalog is on line.
    batteries with or without solder tabs installed.
    no minimum order.

    I have had very good luck with their warranty too..

    don
     
  3. W9GB

    W9GB Ham Member

    Willie -

    This part is readily available from Digi-Key, IN STOCK (thousands in stock). $1.10 each !!
    http://www.digikey.com/catalog/en/partgroup/cr-coin-series/3437?col=battery-cell-size&print=1

    SOLDER-TAB Lithium Coin cells are used in millions of RFID and Toll-road vehicle transponders!
    ===
    GET the Yaesu FT-747GX (Technical Supplement) Service Manual, Fox Tango (Yaesu Int'l Users Group)
    http://www.foxtango.kc9foz.com/Eighties/Eighties.htm

    PAGES 12-14 have the PC board layout, parts list, schematic.
    Your specific part is: BAT01 -- Yaesu part number: Q9000106, CR2025-HM1
    You can use a CR20xx or BR20xx with the correct solder tab configuration,
    the CR2032 is more popular (higher capacity).

    1. TODAY, Panasonic is major mfg. (~ 75% market) of these coin cells.
    They bought out Sanyo, a few years ago.

    2. Panasonic makes both BR and CR coin cells.
    Lithium Coin Cell Handbook -- Coin Cells, Diagrams, Solder Tab suffix diagrams.
    http://www.digchip.com/datasheets/d...id=1833019&part-number=CR2025/1F2&show=inline

    3. Failure of D8 or D9 can cause pre-mature or fast discharge of the memory battery.
    ==
    While you are there, 3 Lamps (PL3001-PL3003), Yaesu # 1000010, BQ041-22803A
     
    Last edited: Jun 3, 2013
  4. KE3WD

    KE3WD Ham Member

    *Desolder the old cell and make a written picture first as to the connections plus and minus so there will be no mistakes when installing the new one.*

    *There are Battery Stores that can spot weld terminals onto a cell to match the ones on yours, just take them the old battery to use as a template.*

    Use the website locators to see if there isn't one near you, they are proliferating now.

    http://www.batteriesplus.com/

    http://www.batteryout.com/page.home

    Do NOT try to solder leads onto a Lithium Cell battery, despite what some hams may tell you on the internet, just not a wise move.

    Some hams go to Radio Shack and pick up a button cell battery holder to fit a cell, then solder its wires to the connection points on the board, check polarity twice before inserting the new coin cell into that holder. Radio Shack also sells double sided sticky foam tape that is handy for placing that cellholder somewhere close inside the radio where it will fit without shorting into anything. With the button cell holder, next time you need to replace the cell, it will be a pop out and pop in situation.


    73
     
  5. W9GB

    W9GB Ham Member

  6. AC0UK

    AC0UK XML Subscriber

    Awesome! Thanks. I just desoldered the battery and it is indeed a CR2025, made by Sony. There was WAY too much solder used by the last replacement and it took a lot of cleanup to get it off. I would like to go with a higher capacity model if it is not any thicker. The 2025 was a snug fit into the slot in the PCB. I'm going to take a drive up to Batteries Plus to see what they have in stock.

    Regarding the lamps, yes, actually all 3 were burned out and I just replaced them. I know it's a simple thing but it was still so satisfying to see the display light up! SO much fun. This is a cool little radio.
     
  7. W9GB

    W9GB Ham Member

    Yaesu must have preferred Sony as their coin cell battery supplier in 1980s.

    The Yaesu FT-736R also used a Sony battery, but mounted vertically on the front panel/display board.
    CR-2032/VCN, Digi-Key P660-ND works as replacement, for that radio.

    WY3A sells a suitable replacement lamp for Yaesu part #: BQ041-228038V 100 MA Lamp Fuse Bulb
    http://www.qsl.net/wy3a/Lamp_Fuse.htm

    The Yaesu part number BQ041-22803 for these lamps, was discontinued long ago. The 757GXII owners manual specifies the part as an 8V 100 ma lamp fuse. While any low current, grain of wheat type lamp, from 6 to 8 volts, is a suitable replacement, its current rating must not exceed 100 mA.

    WY3A found some grain of wheat 6.5V / 68mA bulbs that are just the right size (T1 size).
     
    Last edited: Jun 4, 2013
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