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Futaba 9-bt-26

Discussion in 'Troubleshooting and Repair' started by RICHARD STETSON, Aug 13, 2017.

  1. RICHARD STETSON

    RICHARD STETSON

    5
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    Aug 13, 2017
    I need a comparable display for this vfd. Any help appreciated.
     
  2. kellys_eye

    kellys_eye

    4,286
    1,146
    Jun 25, 2010
    What equipment is it from?

    You will only likely find one in some old equipment anyway - rare as rocking horse droppings.
     
  3. Bluejets

    Bluejets

    3,432
    697
    Oct 5, 2014
    Digi Key have vfd's but you'll have to troll though the specs. to find one that suits.
     
  4. 73's de Edd

    73's de Edd

    2,616
    1,067
    Aug 21, 2015
    http://www.ebay.com/itm/9-BT-28ZA-F...9BT28ZA-NEW-/253082186410?hash=item3aecdfb2aa

    We know that the 9-BT- prefix for the number of digits agree,but, how about that 28ZA aspect now?
    These / this may be the only OEM unit(s)left on this planet.
    I would venture an educated guess that the 28 might be relevant to a 2 decimal 8V serpentine filament string voltage .
    I wasn't big on VFD's . . . . . so my 70 yr old documents library is totally void of any Futaba.data sheets/books.

    73's de Edd
     
  5. RICHARD STETSON

    RICHARD STETSON

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    Aug 13, 2017
    vfd is from mettler AE balance
     
  6. 73's de Edd

    73's de Edd

    2,616
    1,067
    Aug 21, 2015
    What is being the fault found on the display on the unit?
    • No display at all ?
    • A missing digit?
    • Missing segments?
    • Dimmness of display?
    Since some or all of these could be attributable to a circuitry fault feeding into the display proper.

    Mettler AE balance
    Model number of that unit ?

    73's de Edd
     
  7. luciof

    luciof

    3
    1
    Mar 16, 2019
    Hi all,

    I know this is an old thread, but maybe my findings can still be useful.

    I own an old but perfectly working Mettler AE240 balance; like all the AE series balances (which share the same display board), its main problem is the VFDisplay getting dim with age.
    Currently, it's virtually impossible to find a new replacement VFD unit, so I bought a couple of 9-BT-28 displays on eBay to give a try.
    There are quite a number available for sale at low prices.

    Compared with the original Futaba 9-BT-26 VFD, the 9-BT-28 shares the same pinout and length; its case is a little bit narrower, but the digits are identical - so a one-to-one replacemente is easily feasible. It looks like the only significant difference is in the filament: the 9-BT-26 measures a cold resistence around 55 ohms, while the 9-BT-28 is only 12 ohms (this is between the extreme pins).
    I replaced the VFD on the balance's display board and - after a little fiddling, I found that a 47 ohms 1W resistor in series with the filament does the trick (this is about the minimum series resistance under which the digits' brightness does not increase noticeably).
    Now the balance shows off a beatiful, bright and uniform turquoise reading, like it has to be.
    P.S.: the 47R has to be placed in series with the first (leftmost) or last (rightmost) pin of the VFD. No PCB modifications are required, and plenty of space is available underneath the VFD body.

    Hope this helps.
     
    73's de Edd likes this.
  8. RICHARD STETSON

    RICHARD STETSON

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    Aug 13, 2017
     
  9. RICHARD STETSON

    RICHARD STETSON

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    Aug 13, 2017
    Great information, is it possible to email me a picture of the resistor placement to [email protected]?
    Thank you
     
  10. luciof

    luciof

    3
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    Mar 16, 2019
  11. luciof

    luciof

    3
    1
    Mar 16, 2019
    Basicly, the procedure for display replacement is the following one:
    - remove the tare bar (be extremely careful, it's very easy to broke it while unscrewing; use proper pliers to keep the square plastic bases from rotating while screwing/unscrewing)
    - cut the disply wires about 1 cm from the PCB to ease subsequent desoldering
    - desolder the pins using a good soldering iron and pliers
    - clear the holes using a good vacuum desoldering tool (this might be a little difficult; adding a little bit of fresh solder before sucking will help)
    - clean the PCB using isopropil alcohol or other flux thinner
    - insert the new display: the leftmost (or rightmost) pin must be left alone (floating); the pins should protrude about 1-2 mm from the PCB underside
    - solder the display pins and adjust the display so it lies against the plastic holders; please note the new display is narrower than the old one, so it won't catch into the brackets. Be careful to not overbend or break the wires
    - insert the resistor into the empty PCB hole, solder it and cut the excess wire
    - shape and cut the other resistor wire so it can be soldered to the floating display pin; solder it
    - temporarily install the display board into the balance to test it (the balance will power on by pressing the right front microswitch)
    - remove the board and replace the tare bar (again, be extra careful!)
    - finally, replace the display board, replace the cover and enjoy!
     
  12. RICHARD STETSON

    RICHARD STETSON

    5
    0
    Aug 13, 2017
    Thank you I will try. Retired from Mettler Toledo and have many bad displays. Have never found a fix.
     
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