Are you sure you have the model number correct?

The only FB-01 info I have found for Yamaha says it is just a sound module with no controls at all. No pitch bend, no mod wheel.
https://www.vintagesynth.com/yamaha/fb01.php

OP is using an external keyboard as a MIDI controller. It's fairly apparent in the text of his query.

My wild guess... it's something to do with MIDI configuration.

Agreed, it probably is a MIDI issue. The FB-01 had 8-note polyphony, and could be as many as 8-way multi-timbral. Make sure you are setting the PB range for the channel you are triggering (as strange as that sounds).
You allocated polyphony among the Parts. Be sure the “Voice Function” for Pitch Bend range is set for the correct Voice 1-8 and Channel.

Say you set it for 8-note polyphony for Voice 1, on Channel 1, then make sure the “Voice Function” setting for Pitch Bender is set to a value other than 0 (1-12 sets the range for both positive and negative bend). There are eight different PB range settings (one for each potential Voice in a program).

36 years ago, yikes!

My wild guess... it's something to do with MIDI configuration.

I've never really understood why people are so reluctant to actually say what equipment and configuration they are using!

OP did say this:

I have it set in the Voice (17/3) for PB = 12 but no pitch bend. Notes play, the modulation wheel works, volume changes, all that you would expect, but no pitch bend.

But the device I see illustrated doesn't have any external devices (PB, Mod wheel) of it's own and OP hasn't said what external keyboard or devices they actually are trying to use.

Maybe they should check p 27 of the manual where it says:

In order to hear the effects of the modulation wheel, the breath controller,
the foot controller, or after tuch, the PMD (pitch modulation device) must
be selected for each of the 8 instruments in the FB-01.

https://www.opl3.com/wp-content/uploads/2018/11/FB01E.pdf

Get ChatGPT to look up "SHS-500"

Yes it is an old synth module. As I said " I have it
set in the Voice (17/3) for PB = 12 but no pitch bend. "
The unit uses these setups, the #17 is a preset setup
that provides 8 voices on one midi channel and it is
not something that can be edited (the 3 is bank #3 of
the preset voices) and the PB = 12 is a one octave of
bend. I am guessing I am an "OP" here and those who
don't remember this unit are commenting here.

I think the preset setup #17 has been changed in some
way so that the pitch bend has been turned off, even
though that is not supposed to be possible. Maybe a
gamma ray changed one bit in the memory?

So strange that it works properly otherwise, you know
as I said it plays notes, the modulation works, the volume
can be changed, all the standard midi commands except
the pitch bend.

I think the preset setup #17 has been changed in some
way so that the pitch bend has been turned off, even
though that is not supposed to be possible. Maybe a
gamma ray changed one bit in the memory?

To the contrary, it is possible; the Voice Functions can be altered by a Configuration (and specifically #17)

Page 22 of the FB-01 Manual specifically states,

“For example, when Configuration memory number 17 is selected, the following items are called up automatically:
……
……
*10. Bender amount is set to 2 (full step)
…..
…..

The asterisk next to item 10… is explained below
”These Voice Function data parameters may be assigned new values that are stored as part of the Configuration data. These values are exactly the same as the Voice Function values that are stored with a Voice, except that they are stored as part of a Configuration. When a Configuration is selected, the Voice Function data stored in the Configuration will override the Voice Function data that is stored with the Voice… “” etc.

I have it set in the Voice (17/3) for PB = 12 but no pitch bend.

Based on the above, the doc, and this from Bad Mister

To the contrary, the Voice Functions can be altered by a Configuration (and specifically #17)

1. your voice has pitch bend set to 12
2. config 17 has pitch bend set to 2
3. you loaded the voice first
4. then loading config 17 overwrote the pitch bend value in the voice so it is now 2

If that is correct, and you like config 17 except for the pitch bend setting: you need to create a custom config. Start with config 17, modify pitch bend to 12 and then store that as a user config.

Then when you load the voice followed by config #7 (if that is your user config with PB=12) that voice will have the correct pitch bend.

As usual, BM can jump all over me if I am wrong!

As usual, BM can jump all over me if I am wrong!

Not because you’re wrong necessarily, (I really don’t know if your info is right or wrong) but because you state as fact, things you couldn’t possibly know. (Your first reply was questioning if the product model even existed…)!

Back in the day of early FM synths, a separate set of parameters, called Functions, was used. By pointing out where in the Owner’s Manual a possible solution could be found, I was hoping to lead the original poster to something they might explore.

When the FB-01 was a current product 1986… predates my time with Yamaha, so I don’t have any in depth first hand knowledge of the unit. But I do know Voice Functions could be handled differently, separate from the rest of the FM program. So there was a set of parameters that could be offset when you created a Configuration…

By the time I put on the Yamaha hat, the whole “Function” thing was changing. So I wouldn’t dare attempt to itemize steps in a solution because that is best verified by pressing buttons and navigating inside the product.
I assume you are just trying to be helpful but… if you are basing your suggestions on how synths work now… well, let’s just say, it would be best to actually have the product in front of you (or at least know it exists). Don’t mean to “jump” on you but

When I turn on the device, it is on configuration #17 with bank 3 #1
and at that time the PB is set to 2. Then I change PB to 12. But it doesn't
matter, there is never any bending of the pitch, not a step and not an
octave. This is just very strange. I had one FB-01 before and know how
to use it. As I said I tried two midi keytar, both of which bend pitch fine
on any other module, or when driving my MODX. Super strange that it
responds to all the other controllers but not pitch bend.

If you are old enough (perhaps Phil is?) the original midi spec did not
use a separate status byte for pitch bend, it was controller 0 instead.
But the FB-01 is not old enough for that, is it? I guess this unit could
have come from a foreign market where the original midi spec was
still in use? Midi 0.1 maybe? Well, probably not but that is what this
situation is like. I still think there must be something strange in the
memory. I would need to find a factory memory reset file and figure
out a way to upload it into the FB-01. I do remember this ancient
module has a very impressive midi implementation.

Forget this particular program for a moment… do any of the programs respond to Pitch Bend?
If no, the unit is broken
If yes, then you should call Customer Service, they can research it for you (because if other factory programs respond, then you are not editing the Configuration properly).