Roland Acoustic Chorus AC-33 Operating and maintenance manual

SERVICE NOTES
Issued by RJA
Copyright © 2010 Roland Corporation
All rights reserved. No part of this publication may be reproduced in any form without the written permission
of Roland Corporation.
CC-KWS17058652E0
Feb. 2010 AC-33
Table of Contents
Cautionary Notes ..............................................................2
Specifications .....................................................................3
Location of Controls .........................................................4
Location of Controls Parts List........................................5
Exploded View (All) .........................................................6
Exploded View (All) Parts List........................................7
Plain View (1).....................................................................8
Plain View (1) Parts List...................................................9
Plain View (2)...................................................................10
Plain View (2) Parts List.................................................11
Exploded View (Fig.A)...................................................12
Exploded View (Fig.A) Parts List .................................13
Plane View (Fig.A) ..........................................................14
Plane View (Fig.A) Parts List.........................................15
Parts List ...........................................................................16
Verifying the Version Number......................................18
Test Mode .........................................................................18
Block Diagram/Wiring Diagram..................................20
Circuit Board (Main Board) ...........................................22
Circuit Diagram (Main Board: Power).........................24
Circuit Diagram (Main Board: Digital) ........................26
Circuit Diagram (Main Board: Analog) .......................28
Circuit Board (Guitar Input, Mic Input, Panel, Jack B,
Phones Board)..................................................................30
Circuit Diagram (Guitar Input Board) .........................32
Circuit Diagram (Mic Input Board) ..............................32
Circuit Diagram (Panel Board)......................................34
Circuit Diagram (Jack B Board).....................................36
Circuit Diagram (Phones Board)...................................37

2
Feb. 2010 AC-33
Cautionary Notes
Before beginning the procedure, please read
through this document. The matters described may
differ according to the model.
No User Data
This product cannot save user data. Backing up user data during servicing is
not required.
Parts List
A component whose part code is ******** will not be supplied as a service part
because one of the following reasons applies.
• Because it is supplied as an assembled part (under a different part code).
• Because a number of circuit boards are grouped together and supplied as
a single circuit board (under a different part code).
• Because supply is prohibited due to copyright restrictions.
• Because reissuance is restricted.
• Because the part is made to order (at current market price).
• Because it is carried in electronic data on the Roland web site.
• Because it is a package or an accessory irrelevant to the function
maintenance of the main body.
• Because it can be replaced with an article on the market. (battery or etc.)
Circuit Diagram
In the circuit diagram, “NIU” is an abbreviation for “Not in Use,” and
“UnPop” is an abbreviation for “Unpopulated.” They both mean non-mounted
components. The circuit board and circuit board diagram show silk-screened
indications, but no components are mounted.
Updating the System
Updating the system is accomplished by replacing the Main Board.

3
Feb. 2010 AC-33
Specifications
AC-33: ACOUSTIC CHORUS
Rated Power Output
15 W + 15 W (when using the AC adaptor)
10 W + 10 W (when using the Alkaline batteries)
Nominal Input Level (1 kHz)
GUITAR Channel: -10 dBu
MIC/LINE Channel: -50 dBu/-20 dBu
AUX IN: -10 dBu
Nominal Output Level (1 kHz)
LINE OUT: -10 dBu
* 0 dBu = 0.775 Vrms
Speakers
12 cm (5 inches) x 2
Controls
(GUITAR Channel)
VOLUME Knob
Equalizer Knobs (BASS, MIDDLE, TREBLE)
CHORUS Switch
(MIC/LINE Channel)
VOLUME Knob
Equalizer Knobs (BASS, TREBLE)
CHORUS Switch
REVERB/AMBIENCE Knob
(ANTI-FEEDBACK)
ON/OFF Switch
(LOOPER)
REC/PLAY/OVERDUB Button
STOP/CLEAR Button
(AUX IN Controls)
LEVEL knob
MASTER knob
POWER Switch
Indicators
REC/PLAY/OVERDUB
POWER
Connectors
GUITAR Channel Input Jack (1/4” phone type)
MIC/LINE Channel Input Jacks (XLR type, 1/4” TRS phone type)
AUX IN Jacks (RCA phono type, Stereo miniature phone type)
LINE OUT (L/MONO, R) Jacks (1/4” phone type)
PHONES Jack (Stereo 1/4” phone type)
FOOT SWITCH Jacks (1/4” TRS phone type)
DC IN Jack
Power Supply
AC Adaptor (included, DC 13 V),
Dry battery LR6 (AA) type (alkaline) x 8, or
Rechargeable battery HR6 (AA) type (nickel metal hydride) x 8
Current Draw
490 mA
Expected battery life under continuous
use:
Alkaline: about 8 hours
Nickel-metal hydride: about 9 hours
* These figures will vary depending on the actual conditions of use.
Dimensions
318 (W) x 223 (D) x 243 (H) mm
12-9/16 (W) x 8-13/16 (D) x 9-5/8 (H) inches
Weight (excluding batteries)
4.7 kg / 10 lbs 6 oz
Accessories
Owner’s Manual (#5100010616)
AC Adaptor (#5100010587)
AC Cord (#5100009482, #5100012740, #5100009486, #5100009483, #5100009484,
#5100009485)
Options
Foot Switch: BOSS FS-5U, BOSS FS-6
Connection Cable: PCS-31
* Printed matters will not be supplied after the end of the production. Then,
download the electronic file from the Roland web site.
* In the interest of product improvement, the specifications and/or appearance of
this unit are subject to change without prior notice.

4
Feb. 2010 AC-33
Location of Controls
fig.panel.eps

5
Feb. 2010 AC-33
Location of Controls Parts List
No. Part Code Part Name Description Q’ty
1 13449146 6.5MM JACK YKB21-5012 (W/SW) 3
5100004356 JACK NUT 3
2 5100011024 R-KNOB 08203-500 2
5100007826 ROTARY POTENTIOMETER RD901F-20E1-125F-1B100K-00D10A 2
* This unit includes the following parts.
******** VR NUT M9 2
******** VR WASHER 2
3 5100011024 R-KNOB 08203-500 7
5100007829 ROTARY POTENTIOMETER RD901F-40E1-125F-0B10K-00D10A 7
* This unit includes the following parts.
******** VR NUT M9 7
******** VR WASHER 7
4 13449252 6.5MM JACK YKB21-5006 (STEREO W/SW) 4
5100004356 JACK NUT 4
5 03459223 XLR CONNECTOR JY-5033A 1
5100011617 EVA PACKING 40X25X1T W/ADH 1
6 5100007725 SWITCH SS71020F-0103-6T-025-NP-017 2
5100010458 HIMELON FOR SLIDE SW 2
7 5100007726 SWITCH SS71010F-0102-6T-015-NP 1
5100010458 HIMELON FOR SLIDE SW 1
8 05017534 LED (YELLOW) L-34YDSL 1
5100004216 LED SPACER LEDH-7 1
9 03349989 LED (GREEN) L-34GDSL-FPB 1
5100004216 LED SPACER LEDH-7 1
10 5100004353 KEYTOP 40285-501(#SD000906) 2
5100010538 EVA PACKING 35X15XT0.5 W/ADH 1
01780101 TACT SWITCH SKQKABD010 2
11 03349978 LED(RED) L-34HDSL-FPB 2
5100004216 LED SPACER LEDH-7 2
12 02897801 SEESAW SWITCH SDDJE13200 94V-0 1
5100010579 WIRING 192-AP011-W4 1
13 5100010457 DC PLUG SUPPORTER 1
14 03562412 DC JACK HEC3900-010110 1
5100009659 DC JACK HOLDER 1
5100010540 EVA PACKING FOR DC JACK HOLDER A 1
15 5100007731 ROTARY POTENTIOMETER R1131GOXH1B203TG0027 1
16 05019512 3.5MM JACK 203-HTJ03509ABT 1
17 5100007830 CONNECTOR RCA KM04048A-01 1

6
Feb. 2010 AC-33
Exploded View (All)
fig.bunkaizu-all.eps
fig.speaker-e.eps
View 2
View 1
View 4
View 3
Refer to Fig.A
6
8
1
9
4
2
7
10
5
3
BLACK
(5100010584)
RED
(5100010583)
BROWN
(5100010586)
ORANGE
(5100010585)
* Terminals are underneath.
When detaching the chassis (Fig. A),
remove the following screws.
• In Plain View (1) (p. 8), the 4 screws at jin View 2
• In Plain View (2) (p. 10), the 2 screws at fin View 3

7
Feb. 2010 AC-33
Exploded View (All) Parts List
No. Part Code Part Name Description Q’ty
1 5100009315 CABINET ASSY 1
* This unit includes the following parts.
******** CABINET 1
******** CATCH 4
******** ABSORPTIVE FOAM 1
2 5100006069 RUBBER FOOT D25XT18 40484-512(#SD001005) 4
3 ******** STAND 1
4 5100009863 STAND HOLDER 40484-518 (#SD001007) 2
5 5100014460 NET BOARD ASSY W/ROLAND BADGE 1
* This unit includes the following parts.
******** ROLAND BADGE 1
******** NET BOARD 1
6 5100010591 BATTERY CASE ASSY 1
7 5100010998 SPEAKER W0504-011 A 2
8 5100011381 HANDLE 1
9 5100011382 HANDLE PLATE 1
10 5100011383 HANDLE HOLDER 2

8
Feb. 2010 AC-33
Plain View (1)
fig.bunkaizu-1.eps
a a
bc
b
j
e
View 1
View 2

9
Feb. 2010 AC-33
Plain View (1) Parts List
View 1
View 2
No. Part Code Part Name Description Q’ty
a 40019023 SCREW 4X20 BINDING TAPPING A BZC 8
No. Part Code Part Name Description Q’ty
b 40237101 SCREW M3X8 PAN MACHINE W/SW+SMALL PW BZC 3
c 40011312 SCREW 3X8 BINDING TAPTITE P FE BZC 1
j 40010689 SCREW 4X25 TRUSS TAPPING A FE BZC 4
e 5100005098 SCREW 3X16 TRUSS TAPPING A BZC 8

10
Feb. 2010 AC-33
Plain View (2)
fig.bunkaizu-2.eps
c
f
d d
g
View 3
View 4

11
Feb. 2010 AC-33
Plain View (2) Parts List
View 3
View 4
No. Part Code Part Name Description Q’ty
c 40011312 SCREW 3X8 BINDING TAPTITE P FE BZC 2
f 40564601 SCREW M5X35 OVALHEAD MACHINE BZC 2
No. Part Code Part Name Description Q’ty
d 40010678 SCREW 4X20 TRUSS TAPPING A FE BZC 4
5100005100 WASHER FLAT 4.2X10X0.5 BZC 4
g 40128012 SCREW M4X16 PAN MACHINE W/SW+PW BZC 4

12
Feb. 2010 AC-33
Exploded View (Fig.A)
fig.bunkaizu-A-e.eps
27
24
Secure the wiring in place using a clamp.
15 mm or less
* Contact between the coil and the wiring is prohibited.
White
11
17
Orientation of the wiring
Wind the wiring (#5100010579)
around the power switch and solder.
Solder
2 locations
(wound)
* The end of the wire must not extend below the connector.
Solder
2 locations (wound)
White spot
Black
View A4
View A1 View A2
View A3
20
20
22
12
25
i
17
14
15
l
23
30
16
18
13
28
26
21
22
22
29
19
27

13
Feb. 2010 AC-33
Exploded View (Fig.A) Parts List
Application Sites for EVA Packing Cushions
Mic Input Board
As shown in the figure, tightly attach the EVA Packing (#5100011617) onto the XLR connector.
fig.EVA-XLR-e.eps
Main Board
Affix the EVA Packing (#5100012099) at the locations shown in the figure.
fig.EVA-Main.eps
Jack-B Board
As shown in the figure, affix the EVA packing (#5100010540) onto the DC Jack
Holder.
fig.EVA-JackB.eps
No. Part Code Part Name Description Q’ty
11 5100010579 WIRING 192-AP011-W4 1
12 5100010457 DC PLUG SUPPORTER 1
13 5100009366 MAIN PWB BOARD ASSY 1
5100009323 PANEL PWB SHEET ASSY 1
* This unit includes the following parts.
14 ******** PHONES BOARD 1
25 ******** GT INPUT BOARD includes a Nut and a Washer (No.29) 1
26 ******** MIC INPUT BOARD includes a Nut and a Washer (No.29) 1
27 ******** JACK-B BOARD 1
28 ******** PANEL BOARD includes Nuts and Washers (No.29) 1
29 ******** Nut 9
******** Washer 9
15 5100010453 CHASSIS 1
16 5100004353 KEYTOP 40285-501(#SD000906) 2
17 02897801 SEESAW SWITCH SDDJE13200 94V-0 1
18 5100010458 HIMELON FOR SLIDE SW 3
19 5100011024 R-KNOB 08203-500 9
20 5100011022 EVA PACKING 110X15X1T W/ADH 2
21 5100010539 EVA PACKING 255X30X1T W/ADH 1
22 5100004356 JACK NUT 7
23 5100010538 EVA PACKING 35X15XT0.5 W/ADH 1
24 5100005099 LOCKING CABLE TIE 120X2.5X1T DAIHWA 1
30 5100012099 EVA PACKING 25X25X1T W/ADH 1
31 5100011617 EVA PACKING 40X25X1T W/ADH 1
32 5100010540 EVA PACKING FOR DC JACK HOLDER A 1
i 5100011021 STANDOFF M3-L6-H20 (311-BG436LF) 2
l 5100011020 STANDOFF M3-L6-H15 (311-BG108LF) 1
26
31
Side:
Attach tightly.
Side:
Attach tightly.
Flat surface:
Attach tightly.
Step:
Attach tightly.
Flat surface:
Attach tightly.
13
13mm
34mm
30
27
32

14
Feb. 2010 AC-33
Plane View (Fig.A)
fig.bunkaizu-3.eps
h
h
h
i
h
hl
View A1
View A2
View A3 View A4

15
Feb. 2010 AC-33
Plane View (Fig.A) Parts List
View A1
View A2
View A3
View A4
No. Part Code Part Name Description Q’ty
h 40012867 SCREW M3X8 PAN MACHINE W/SW+PW ZC 5
No. Part Code Part Name Description Q’ty
h 40012867 SCREW M3X8 PAN MACHINE W/SW+PW ZC 2
i 5100011021 STANDOFF M3-L6-H20 (311-BG436LF) 2
No. Part Code Part Name Description Q’ty
h 40012867 SCREW M3X8 PAN MACHINE W/SW+PW ZC 2
No. Part Code Part Name Description Q’ty
h 40012867 SCREW M3X8 PAN MACHINE W/SW+PW ZC 1
l 5100011020 STANDOFF M3-L6-H15 (311-BG108LF) 1

16
Feb. 2010 AC-33
Parts List
fig.-part1-e.eps
Safety Precautions:
The parts marked have
safety-related characteristics. Use
only listed parts for replacement.
Note: The parts marked # are new. (initial parts) The description “Q’ty” means a necessary number of the parts per one product.
Due to one or more of the following reasons,
parts with parts code ******** cannot be supplied as service parts.
• Part supplied only as a component in a complete assembly
• Copyright does not permit the part to be supplied
• Part is sold commercially
CASING
# 5100009315 CABINET ASSY 1
# 5100010591 BATTERY CASE ASSY 1
# 5100014460 NET BOARD ASSY W/ROLAND BADGE 1
CHASSIS
# 5100010453 CHASSIS 1
KNOB, BUTTON
5100004353 KEYTOP 40285-501(#SD000906) 2
# 5100011024 R-KNOB 08203-500 9
SWITCH
01780101 TACT SWITCH SKQKABD010 2
02897801 SEESAW SWITCH SDDJE13200 94V-0 1
# 5100007725 SWITCH SS71020F-0103-6T-025-NP-017 2
# 5100007726 SWITCH SS71010F-0102-6T-015-NP 1
JACK, EXT TERMINAL
03459223 XLR CONNECTOR JY-5033A 1
# 03562412 DC JACK HEC3900-010110 1
05019512 3.5MM JACK 203-HTJ03509ABT 1
13449146 6.5MM JACK YKB21-5012 (W/SW) 3
13449252 6.5MM JACK YKB21-5006 (STEREO W/SW) 4
5100007830 CONNECTOR RCA KM04048A-01 1
SPEAKER, BUZZER
# 5100010998 SPEAKER W0504-011 A 2
PWB ASSY
# 5100009366 MAIN PWB BOARD ASSY 1
# 5100009323 PANEL PWB SHEET ASSY 1
* This unit includes the following parts.
# ******** PANEL BOARD 1
# ******** GT INPUT BOARD 1
# ******** MIC INPUT BOARD 1
# ******** PHONES BOARD 1
# ******** JACK-B BOARD 1
DIODE
03349978 LED (RED) L-34HDSL-FPB 2
03349989 LED (GREEN) L-34GDSL-FPB 1
05017534 LED (YELLOW) L-34YDSL 1
POTENTIOMETER
5100007731 ROTARY POTENTIOMETER R1131GOXH1B203TG0027 1
# 5100007826 ROTARY POTENTIOMETER RD901F-20E1-125F-1B100K-00D10 2
# 5100007829 ROTARY POTENTIOMETER RD901F-40E1-125F-0B10K-00D10A 7
FUSE, FUSE HOLDER
# 5100011069 FUSE MET 0.250 1
# 5100011086 FUSE MET 002 1
# 5100011065 FUSE MET 3.150 1

17
Feb. 2010 AC-33
WIRING, CABLE
# 5100010578 WIRING 192-AP011-W3 1
# 5100010579 WIRING 192-AP011-W4 1
# 5100010583 WIRING 196-AP011-W8 1
# 5100010584 WIRING 196-AP011-W9 1
# 5100010585 WIRING 196-AP011-W10 1
# 5100010586 WIRING 196-AP011-W11 1
SCREWS
40012867 SCREW M3X8 PAN MACHINE W/SW+PW ZC 10
40237101 SCREW M3X8 PAN MACHINE W/SW+SMALL PW BZC 3
40128012 SCREW M4X16 PAN MACHINE W/SW+PW BZC 4
40564601 SCREW M5X35 OVALHEAD MACHINE BZC 2
5100005098 SCREW 3X16 TRUSS TAPPING A BZC 8
40011312 SCREW 3X8 BINDING TAPTITE P FE BZC 3
# 40019023 SCREW 4X20 BINDING TAPPING A BZC 8
40010678 SCREW 4X20 TRUSS TAPPING A FE BZC 4
40010689 SCREW 4X25 TRUSS TAPPING A FE BZC 4
# 5100004356 JACK NUT 7
5100005100 WASHER FLAT 4.2X10X0.5 BZC 4
# 5100011020 STANDOFF M3-L6-H15 (311-BG108LF) 1
# 5100011021 STANDOFF M3-L6-H20 (311-BG436LF) 2
MISCELLANEOUT
# 5100011381 HANDLE 1
# 5100011382 HANDLE PLATE 1
# 5100011383 HANDLE HOLDER 2
5100004216 LED SPACER LEDH-7 4
5100009863 STAND HOLDER 40484-518 (#SD001007) 2
5100006069 RUBBER FOOT D25XT18 40484-512(#SD001005) 4
# 5100009659 DC JACK HOLDER 1
# 5100010457 DC PLUG SUPPORTER 1
5100005099 LOCKING CABLE TIE 120X2.5X1T DAIHWA 1
# 5100010458 HIMELON FOR SLIDE SW 3
# 5100012099 EVA PACKING 25X25X1T W/ADH 1
# 5100010538 EVA PACKING 35X15XT0.5 W/ADH 1
# 5100010539 EVA PACKING 255X30X1T W/ADH 1
# 5100010540 EVA PACKING FOR DC JACK HOLDER A 1
# 5100010541 EVA PACKING FOR DC JACK HOLDER 1
# 5100011022 EVA PACKING 110X15X1T W/ADH 2
# 5100011617 EVA PACKING 40X25X1T W/ADH 1
ACCESSORIES (Standard)
# 5100010587 AC ADAPTOR PSB-12U 1
5100009481 AC CORD 181-AP009-J 100V 1.0M 1
5100009482 AC CORD 181-AP009-UC 117V 1.0M 1
# 5100012740 AC CORD 181-AP009-BL 117VBL 1.0M 1
5100009486 AC CORD 181-AP009-CN 220VCN 1.0M 1
5100009483 AC CORD 181-AP009-G 230V EU 1.0M 1
5100009484 AC CORD 181-AP009-B 230VE 1
5100009485 AC CORD 181-AP009-A 240VA 1.0M 1
# 5100010615 OWNER’S MANUAL JAPANESE 1
# 5100010616 OWNER’S MANUAL MULTILANGUAGE 1

18
Feb. 2010 AC-33
Verifying the Version
Number
Items Required
• Foot switches (BOSS FS-5U) x 2
• Foot-switch connection cable (PCS-31) x 1
Procedure
1. Connect a foot switch to the FOOT SW EFFECTS jack.
The PCS-31 foot-switch connection cable is an adapter cable from stereo
to mono x 2.
The white end of the mono standard plug is for TIP:CHORUS, and the
red end is for RING:REVERB/AMBIENCE.
2. Connect the monaural standard plugs to the respective FS-5U foot
switches.
You can connect the white and red ends to either FS-5U unit.
Set the polarity switches on the FS-5U units to the “jack” side.
3. Make the following settings on the main unit.
• POWER switch: OFF
• GUITAR CHANNEL CHORUS: OFF
• MIC/LINE CHANNEL CHORUS: OFF
• ANTI-FEEDBACK: OFF
• All controls: Minimum
4. Hold down the TIP:CHORUS (white) foot switch and switch on the
power.
Immediately after the power is switched on, all LEDs light up.
* Continue to hold down the foot switch.
5. All LEDs light up, then flash once. Within 3 seconds of this, press the
TIP:CHORUS (white) foot switch twice.
All LEDs flash rapidly several times, then flash to indicate the software
version.
The POWER LED lights up in an intermittent pattern that indicates the
software version as shown below.
6. Switch off the power to the unit.
Test Mode
Items Required
• Foot switches (BOSS FS-5U) x 2
• Foot-switch connection cable (PCS-31) x 1
• Level meter (used only during signal-level testing)
• Signal generator (only when inspecting the signal level)
• Dummy load resistor tool (only during signal-level testing)
Resistor (4Ω, 100 W or more)
Stereo standard plug with 100Ω(1/2 W or more) load resistor connected
between L, R, and GND
Standard plug with 47 kΩload resistor connected between HOT and
GND
Entering the Test Mode
Go to Verifying the Version Number (p. 18) and carry out steps 1through 5.
After verifying the version number, depress the TIP:CHORUS (white) foot
switch connected to the FOOT SW EFFECTS jack to enable the first test item,
1. DSP Test.
Quitting the Test Mode
Switch off the power.
Skipping
Test items cannot be skipped.
1. DSP/SDRAM Test
When testing starts, all LEDs go dark.
The LOOPER LEDs light up in the sequence of REC -> PLAY -> OVERDUB to
indicate the progress of the testing.
If the Test Is Passed (OK)
Execution automatically advances to the next test.
If the Test Is Failed (Not OK)
The POWER LED flashes rapidly. Execution does not advance to the next test.
Version POWER LED illumination pattern
1.00 One long and no short
1.01 One long and one short
1.02 One long and two short
1.03 One long and three short
: :
2.00 Two long and no short

19
Feb. 2010 AC-33
2. Switch Test
Carry out operations in the sequence shown below, and check the status of the corresponding LEDs.
o: illuminated, -: dark, *: flashing
When the operations up through No. 18 have been completed, the POWER LED flashes.
Inserting the foot-switch plug into the EFFECTS jack and depressing TIP:CHORUS (white) makes execution advance to the next test.
3. Volume Test (1)
When the volume test starts, all LEDs light up.
Working in the sequence shown below, change the settings of the controls
from minimum to intermediate and to maximum and vice versa, and verify
that the LEDs light up and the speaker plays sound.
1. GUITAR CHANNEL BASS
2. GUITAR CHANNEL MIDDLE
3. GUITAR CHANNEL TREBLE
4. REVERB/AMBIENCE
5. MASTER
6. MIC/LINE CHANNEL TREBLE
7. MIC/LINE CHANNEL BASS
On detection of minimum value: The OVERDUB LED lights up.
On detection of intermediate value: The PLAY LED lights up.
On detection of maximum value: The REC LED lights up.
The volume level of the speaker sound increases as the control is operated
toward the maximum position, and from the intermediate position on, the
pitch rises.
When all volume testing has been completed, all LEDs flash.
This concludes the testing.
4. Signal-level Test (for Reference)
After 3. Volume Test (1) has been completed, depress TIP:CHORUS (white)
to enter the Signal-level Test mode.
1. When verifying speaker output, connect a 4Ωload resistor to the speaker
lines. When verifying headphones output, connect a 1/4-inch stereo
phone plug with 100Ωload resistors (x 2) to the PHONES jack.
2. Connect a 1/4-inch phone plug with a 47 kΩload resistor to the LINE
OUT jack.
3. Connect a signal generator to the INPUT or AUX IN jack and input the
signal described below.
GUITAR CHANNEL INPUT: -10 dBu, 1 kHz, sine wave
MIC/LINE CHANNEL INPUT(balanced): -42 dBu, 1 kHz, sine wave
(unbalanced): -36 dBu, 1 kHz, sine wave
AUX IN L and R: -23 dBu, 1 kHz, sine wave
* 0 dBu = 0.775 Vrms
4. Set the panel controls as shown below.
CHORUS: OFF
ANTI-FEEDBACK: OFF
GUITAR CHANNEL VOLUME: Maximum
MIC/LINE CHANNEL VOLUME: Maximum
AUX IN LEVEL: Maximum
Other controls: Minimum
5. Verify the values at the measurement points shown in the Circuit
Diagram (Main Board: Analog) (p. 28).
The allowed range for measured values is ±1.5 dBu.
5. Volume Test (2)
1. Reset the power and start the unit in the normal usage state.
2. Input a signal to GUITAR CHANNEL INPUT, turn the GUITAR
CHANNEL VOLUME control, and verify that the volume level changes
normally and that no noise occurs.
3. Carry out verification in the same way for MIC/LINE CHANNEL as well.
No. Operation REC LED PLAY LED OVERDUB LED POWER LED
(Initial state) - - - o
1 Set MIC/LINE CHANNEL CHORUS to SPACE. o o o o
2 Set MIC/LINE CHANNEL CHORUS to WIDE. o o - o
3 Set GUITAR CHANNEL CHORUS to SPACE. o - - o
4 Set GUITAR CHANNEL CHORUS to WIDE. - - - o
5 Set ANTI-FEEDBACK to ON. o o o o
6 Press LOOPER STOP/CLEAR. o o - o
7 Press LOOPER REC/PLAY/OVERDUB. o - - o
↓****
8 Disconnect the foot-switch plug from EFFECTS. - - - o
9 Insert the foot-switch plug into EFFECTS. o o o o
10 Depress the TIP (white) side of the foot switch. o o - o
11 Depress the RING (red) side of the foot switch. o - - o
12 Disconnect the foot-switch plug from EFFECTS. - - - o
13 Insert the foot-switch plug into LOOPER. o o o o
14 Depress the TIP (white) side of the foot switch. o o - o
15 Depress the RING (red) side of the foot switch. o - - o
16 Disconnect the foot-switch plug from LOOPER. - - - o
17 Insert the 1/4-inch stereo phone plug into PHONES. o o o o
18 Disconnect the 1/4 stereo phone plug from PHONES. - - - *

20
Feb. 2010 AC-33
Block Diagram/Wiring Diagram
fig.block.eps@L
A
B
I
J
K
GH
LM