Roland FR-4X Owner's Manual page 18

Appendix
Left-hand button keyboard section
21
Left-hand register buttons
Select the register that is played by the left-hand keyboard.
22
Left-hand button keyboard
These 120 buttons are used to play bass notes and chords (they are
velocity-sensitive). They also allow you to play drum sounds.
Display
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25
Connection panel
27 28
29
18
26
30 31 32 33
21
22
23
Bellows resistance regulator and air button
The bellows resistance regulator allows you to specify the bellows'
inertia (the force needed to push and pull it).
By pressing the air button you can purge the air that still remains in
the bellows after playing (p. 6).
24
Display
Shows information related to your operations.
25
[USER PROGRAM] indicator
This is lit if a user program is selected.
26 [A: 1-7/B: 8-14] indicator
This is unlit if a bank A sound is selected for the right-hand register
buttons, and lit if a bank B sound is selected. Use the [A/B] button
to switch between banks A and B.
27 DC IN jack
Connect the included AC adaptor here.
By installing separately sold rechargeable nickel-metal hydride
batteries (10 batteries), you can use the instrument without an AC
adaptor.
28
MIDI OUT/IN jack
This connector transmits or receives MIDI data. You can switch it
between input and output.
& "Reference Manual" (PDF)
23