Hi JWB,
First you have to find out where the filament is.
Take your multimeter, a cup of coffee and a box
of chocolate biscuits and start testing.
You should have a reading between 5 and 20 ohms.
Then you apply a voltage to these terminals, start
with 3 volt, AC or DC is of no importance at this
stage. Look at the display, the filaments, the seven (?)
horizontal lines accross the display, should NOT glow.
If they are not visible, increase the filament voltage
to 5 volt. If they are still not visible the filament
voltage is probably right. I measured 5 volt/300mA.
However all other displays I measured were 3 volt types.
With one exception, a small five digit display which
seemed to be happy with only 1,5 volt/200 mA.
These vfd's have direct heated cathodes which means
that the filament is also the cathode.
Connect the negative terminal of a 12 volt power supply to one
of the filament connections and connect two wires with
alligator clips to the positive terminal of the power supply.
Connect these test leads "somewhere" on the display and move
them around and observe what happens. You might get some
faint glows but continue until you get a segment that glows
bright. One of the two connections is a grid, now you only
have to determine which one. Start moving one test lead
from one connection to another and observe the display.
If you can light different segments of a digit these are
the anodes. If you can light the same segment in different
digits then you have found the grids . . . .
If you are going to use this displays remember that it is
a multiplexed display and 12 volts will certainly be too
low to get a bright display, therefore you will have to
increase the supply voltage to . . . . something between
30 and 40 volt (50 volt is the maximum anode to cathode voltage).
This voltage will depend on the size of the characters and the
number of grids, your guess is as good as any.
Another important detail is the filament voltage.
The cathodes are directly heated therefore there will be
a voltage drop accross the filament/cathode and all digits
will have a different anode to cathode voltage and therefore
a different brightness. You can overcome this problem by
using an AC voltage for the filament. A center tapped
transformer would be ideal but not strictly necessary.
I tested several displays, the one from the CD player has
only 6 grids. REPEAT 1, TITLE, CH and the segments of the
two large digits below are addressed by grid 2, everything
to the left is addressed by grid 1 . . .
The second 11 digit display has 11 grids, I only tested
a few digits and segments to confirm what I already knew
because the grids are clearly visible and they look like
grids too.
Check also the Futaba site for datasheets and application notes.
Futaba Corporation of America
Have much fun !
on1aag.