Specifications - Fender ACOUSTASONIC JUNIOR Service Manual

ACOUSTASONIC JUNIOR
Product Release No.: PR 334 (This is not a model number)
Part Number: 120V Version 22-1302
240V Aust
230V UK
230V EUR
100V
Power Requirements: 100V Version: 100 VAC, 50/60 Hz, 300W
120V Version: 120 VAC, 60 Hz, 300W
230V
240V Version: 240 VAC, 50 Hz, 300W
Power Amplifier Section
Power output: 40 Watts RMS per channel, (80W RMS Total)
into 8 ohms @ < .12% THD, both channels driven
Sensitivity: 640 mV @ stereo effects return (both channels)
Preamp Section
Input Impedance: 10 MΩ (inst), 3.6 kΩ (Mic), 36.4 kΩ (Line/Inst)
Sensitivity For
Full Power: 12.75 mV (Inst), 5 mV (Mic), 50 mV (Line/Inst)
Tone Controls: Treble +/- 15dB @ 15kHz (Inst) & (Mic/Line/Inst)
Mid +/- 12dB @ 1 kHz (Inst)
Bass +/- 12dB @ 100Hz (Inst), +/- 12dB @ 50Hz (Mic/Line/Inst)
Feedback Notch: -10dB from 80Hz to 700Hz (Instrument Channel)
String Dynamics: 0 to -15dB @ 6.3kHz (Instrument Channel)
Phantom Power: +15VDC (Mic)
Speaker Complement: Two 8 Ohm Special Design 8" Speakers (P/N 051016)
Single Piezo Horn (P/N 049260)
Dimensions: Height:15.5"
Width: 22.4"
Depth: 10.2"
Weight: 43 lbs.
Product specifications are subject to change without notice

SPECIFICATIONS

22-1332
22-1342
22-1362
22-1372
: 230 VAC, 50 Hz, 300W
(39 cm)
(57 cm)
(26 cm)
(19.5 kg)
Bass
Ch. 1
Inst
EQ Mid
Preamp
Treble
Gain
(+)
Line/Inst Ch. 2
(-)
Preamp
Mic
Gain
Mic
Reverb
Send
Footswitch
Rate
Chorus
(Note 2)
in/out
Note 1: S1=Ch. 1 Reverb out/in
S3=Ch. 2 Chorus out/in
Note 2: S4= Master chorus out/in is over-ridden
by the footswitch being plugged in.
The Acoustasonic Jr. is a very different kind of guitar amplifier. The following discussion will introduce the service
technician to it's unusual organization and features (refer to Fig. 1):
INSTRUMENT CHANNEL
The Instrument Channel (Ch. 1) is implemented with operational amplifiers, and has some very useful features:
a) The Feedback Notch Filter provides a 10 dB reduction at the center frequency (which is sweepable
from 80 Hz to 700 Hz.) This easily controls the most common feedback frequency of 240 Hz.
b) The String Dynamics circuit provides a way of varying the amplitude of the 6.3 kHz region of the
overall frequency response (to compensate for a sometimes-present harshness of the piezo pickups.)
2
ACOUSTASONIC JUNIOR
THEORY OF OPERATION
Feedback
String Mono
Effects
Notch
Dynamics
Loop
Filter
String
Notch
Dynamics
Treble
Phase
EQ
Select
(S2)
Bass
Reverb Master
Reverb
(+)
Stereo Stereo
(L)
EFX EFX
U10A
(-)
Send
Return
Switching
Phase
Logic
(S5)
Select
(Note 1)
(+)
Stereo
Stereo
(R)
EFX
U10B EFX
(-)
Send Return
Depth
Chorus
Fig. 1 Block Diagram
Return
Send
L
Pwr L.Spkr
Amp
R
R.Spkr
Pwr
Amp