BOSSCO gt-8 Operating and maintenance manual

SERVICE NOTES
Issued by RJA
Copyright © 2004 ROLAND CORPORATION
All rights reserved. No part of this publication may be reproduced in any form without the written permission
of ROLAND CORPORATION.
Printed in Japan (0500) (AS)17058309E0
Dec.2004 GT-8
TABLE OF CONTENTS
CAUTIONARY NOTES........................................................ 2
SPECIFICATIONS................................................................. 2
LOCATION OF CONTROLS............................................... 4
LOCATION OF CONTROLS PARTS LIST ....................... 6
EXPLODED VIEW ................................................................ 8
EXPLODED VIEW PARTS LIST ....................................... 10
WIRING DIAGRAM........................................................... 11
WIRING DIAGRAM PARTS LIST.................................... 11
PARTS LIST.......................................................................... 12
CHECKING THE VERSION NUMBER........................... 17
USERS DATA SAVE AND LOAD.................................... 17
FACTORY RESET INSTRUCTIONS .................................18
SYSTEM SOFTWARE UPDATING INSTRUCTIONS....19
TEST MODE.......................................................................... 19
BLOCK DIAGRAM .............................................................24
CIRCUIT BOARD (MAIN SHEET) ...................................26
CIRCUIT DIAGRAM (MAIN SHEET 1/3) (Power) .......30
CIRCUIT DIAGRAM (MAIN SHEET 2/3) (Jack) ...........32
CIRCUIT DIAGRAM (MAIN SHEET 2/3) (Digital) ......34
CIRCUIT BOARD (SW SHEET).........................................36
CIRCUIT DIAGRAM (SW SHEET) ...................................38
ERROR MESSAGES............................................................. 40

2
Dec.2004
CAUTIONARY NOTES
User data status
User data status after each of the following processes is described below.
Whenever carrying out procedures that involve deleting or erasing user data,
always be sure to back up the user data to some form of external media (refer
to Saving and Loading Data).
* Executing Test Mode during Factory Reset deletes the user data.
PARTS LIST
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
CIRCUIT BOARD
NIU meant that "NOT IN USE " there don't set any contents in the Circuit
Diagram.
There has silk-screen only in the Circuit Board.
SPECIFICATIONS
GT-8: Guitar Effects Processor
AD Conversion
24 bit + AF method
DA Conversion
24 bit
Sampling Frequency
44.1 kHz
Program Memories
340: 140 (User) + 200 (Preset)
Nominal Input Level
INPUT: -10 dBu
RETURN: -10 dBu
Input Impedance
ΙΝΠΥΤ: 1 Μ Ω
RETURN: 220 Ω
Nominal Output Level
OUTPUT: 0 dBu
SEND: -10 dBu
Output Impedance
OUTPUT: 2 k Ω
SEND: 2 k Ω
Digital Output
EIAJ CP1201, S/P DIF
Dynamic Range
100 dB or greater (IHF-A)
Controls
< Front Panel >
PATCH LEVEL knob
(PREAMP/SPEAKER)
TYPE knob
GAIN knob
BASS knob
MIDDLE knob
TREBLE knob
PRESENCE knob
LEVEL knob
On/Off button
TYPE VARIATION button
CHANNEL button
SOLO button
SPEAKER button
(OVERDRIVE/DISTORTION)
TYPE knob
DRIVE knob
LEVEL knob
On/Off button
TYPE VARIATION button
(DELAY)
FEEDBACK knob
LEVEL knob
On/Off button
TAP button
(CHORUS)
LEVEL knob
On/Off button
(REVERB)
LEVEL knob
On/Off button
(COMP)
On/Off button
(EQ)
On/Off button
(WAH)
On/Off button
(LOOP)
On/Off button
(FX-1)
On/Off button
(AMP CTL)
On/Off button
(FX-2)
On/Off button
(MASTER)
MASTER button
PATCH/VALUE dial
PARAMETER buttons
OUTPUT SELECT button
EXIT button
WRITE button
SYSTEM button
EFFECT CHAIN button
NAME button
Process User Data
Checking Version number Preserved
Factory Reset Deleted
System Update Preserved
Test Mode Preserved

3
GT-8
TUNER/BYPASS button
CTL/EXP button
VARIABLE button
MANUAL button
BANK pedals
Number pedals
CTL pedal
Expression pedal
Expression pedal switch
<Rear Panel>
OUTPUT LEVEL knob
POWER switch
Display
16 characters, 2 lines (backlit LCD)
2 characters, 7 segment LED
Connectors
INPUT jack
OUTPUT jacks L (MONO)/R
PHONES jack
SEND jack
RETURN jack
AMP CONTROL jack
SUB EXP PEDAL/SUB CTL PEDAL1,2 jack
DIGITAL OUT connector (coaxial)
MIDI connectors IN/OUT
AC Adaptor jack
Power Supply
AC 14 V; Supply AC adaptor (BOSS BRC series)
Current Draw
650 mA
Dimensions
515 (W) x 261 (D) x 75 (H) mm
20-5/16 (W) x 10-5/16 (D) x 3 (H) inches
Maximum height:
515 (W) x 261 (D) x 107 (H) mm
20-5/16 (W) x 10-5/16 (D) x 4-1/4 (H) inches
Weight
4.8 kg/10 lbs 10 oz (excluding AC Adaptor)
Accessories
AC Adaptor BRC-240AT (#G2457142)
BRC-230T (#G245714101)
BRC-120T (#G2457144)
BRC-100T (#G2457143)
Owner's Manual English:(#G6047002)
Japanese:(#G6047001)
Read This First (leaflet) (#G6047005)
USER Patch List (#G6027108)
PRESET PATCH LIST (#G6027107)
Roland Service (information sheet) (#********)
Options
Foot Switch: FS-5U, FS-5L
Dual Foot Switch: FS-6
Expression Pedal:
EV-5 (Roland), FV-300L
Foot Switch Cable: PCS-31 (Roland)
(1/4 inches Phone Plug (stereo) - 1/4 inches Phone Plug (mono) x 2)
MIDI IMPLEMENTATION ENGLISH: (#17041558)
JAPANESE: (#17041557)
*0dBu = 0.775Vrms
* In the interest of product improvement, the specifications and/or appearance of
this unit are subject to change without prior notice.
* AF Method (Adaptive Focus method)
This is a proprietary method from Roland & BOSS that vastly improves the
signal-to-noise (S/N) ratio of the A/D and D/A converters.

5
Dec.2004 GT-8
LOCATION OF CONTROLS
fig.haichi.eps
1.2. 1.3.4. 5. 6. 7. 8. 9.
10.11.12.
13.14.
15.16.14.
17.18. 20. 21.22.
23. 24. 25. 26. 27.
30.31.32.33.
34. 35.36.37.38.
39.40.41.
42.43.
44.
45.46. 47.
48.
49.
50.51.
52.
53.
28. 29. 17.19.

6
Dec.2004
LOCATION OF CONTROLS
PARTS LIST
No. PART CODE CATEGORY PART NAME DESCRIPTION Q'TY
1 G2477122 KNOB,BUTTON R-KNOB 15
2 F3279803 POTENTIOMETER POTENTIOMETER 11 CLICKS 50KB RD901-40-125F-B54-11D 2
3 F3279802 POTENTIOMETER POTENTIOMETER NO CLICK 50KB RD901-40-125F-B54-00D 13
4 G2237113 MISCELLANEOUS GUARD PLATE 1
5 G2237112 MISCELLANEOUS GUARD 1
6 75D912C000 CASING TOP COVER 1
7 F5029412 DISPLAY UNIT 7SEG LED A-552SR BW 1
8 G2567119 MISCELLANEOUS DISPLAY COVER 1
9 F5029405 DISPLAY UNIT LCD LMC-SSC2K16DLNY-H01 1
10 F2477101 KNOB,BUTTON DR-KNOB 1
11 01905467 ENCODER ROTARY ENCODER EVE GC1 F20 24B 1
12 G2567118 MISCELLANEOUS ESCUTCEON 1
13 G247751301 KNOB,BUTTON VGA KEYTOP S WITHOUT LENS 12
14 F3129306 SWITCH SWITCH SKQKAB 32
15 G247751001 KNOB,BUTTON VGA KEYTOP S BLACK WITH LENS 20
16 F5029117 DIODE LED L-312LRD 20
17 1502928100 DIODE LED (RED) L-34HDSL 8
18 H2369401 MISCELLANEOUS SPACER 3X6X10 7
19 H2369431 MISCELLANEOUS LED SPACER 3-2 1
20 G2357112 MISCELLANEOUS VR PLATE 1
21 G2637107 MISCELLANEOUS RUBBER SW 1
22 G2567121 MISCELLANEOUS RUBBER SW ESCUTCHEON 1
23 G2217138 MISCELLANEOUS PEDAL LABEL(1) 1
24 G2217139 MISCELLANEOUS PEDAL LABEL(2) 1
25 G2217140 MISCELLANEOUS PEDAL LABEL(3) 1
26 G2217143 MISCELLANEOUS PEDAL LABEL(4) 1
27 G2217144 MISCELLANEOUS PEDAL LABEL(CTL) 1
28 G2217142 MISCELLANEOUS PEDAL LABEL(DOWN) 1
29 G2217141 MISCELLANEOUS PEDAL LABEL(UP) 1
30 G2187602 CASING SWITCH PEDAL 7
31 G2357109 CASING PEDAL FOOT 7
32 G2177103 MISCELLANEOUS SUPPORT SPRING 7
33 03344723 SWITCH TACT SWITCH SKQKAKD010 7
34 G2227301 CASING PEDAL ESCUTCHEON 7
35 75D9122S00 CASING VR PEDAL UNIT INC. VR PLATE 1
36 G2187904 MISCELLANEOUS PEDAL HOLDER 1
37 F3279782 POTENTIOMETER POTENTIOMETER RK11K1140(10K SPECIAL B-CURVE) 1
38 G2357111 MISCELLANEOUS CUSHION R 1
39 G1889117 MISCELLANEOUS PIN STAY 1
40 G2147806 MISCELLANEOUS STAY 1
41 G2147874 MISCELLANEOUS BOLT HOLDER 2
42 G2357120 CASING FOOT H=5 5
43 75D912E000 CASING BOTTOM COVER 1
44 13449155MF JACK,EXT TERMINAL PHONE JACK (MONO) HTJ-064-12I 5
45 01340412 KNOB,BUTTON P R-KNOB SF-A BLK/LCG 1
46 F3229161 POTENTIOMETER 9M/M ROTARY POT. RK09K12A0 (50KAX2) 1
47 13449150MF JACK,EXT TERMINAL JACK (STEREO) HTJ-064-12D 3
48 F3449121 JACK,EXT TERMINAL YKC21-3117 RCA (PIN) JACK 1
49 13429825 JACK,EXT TERMINAL MIDI CONNECTOR YKF51-5054 2PZ 1
50 12499175 KNOB,BUTTON BUTTON JSPUE001A 1
51 F3129307 SWITCH PUSH SWITCH SDKLA1-B 1
52 13449728 JACK,EXT TERMINAL ADAPTOR JACK HEC0740-010010 1
53 F2367103 MISCELLANEOUS CORD HOOK 1

7
GT-8

9
Dec.2004 GT-8
EXPLODED VIEW
fig.bunkai.eps
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
22
23
24
25
26
27
28
29
34
35
36 37
38
40
39
a
b
c
d
e
f
g
h
I
I
I
I
j
k
kk
m
k
k
30
n
31 32
33
41
30
o
p
q
r
s
33
42
2120 20 20 21 20
21
21

10
Dec.2004
EXPLODED VIEW PARTS LIST
[Parts]
[Screw]
No. PART CODE PART NAME DESCRIPTION Q’TY
1 75D912C000 TOP COVER 1
2 75D912E000 BOTTOM COVER 1
3 G2237112 GUARD 1
4 G2237113 GUARD PLATE 1
5 G2637107 RUBBER SW 1
6 G2567121 RUBBER SW ESCUTCHEON 1
7 G2357120 FOOT H=5 5
8 G2567119 DISPLAY COVER 1
9 12499175 BUTTON JSPUE001A 1
10 F2477101 DR-KNOB 1
11 01340412 P R-KNOB SF-A BLK/LCG 1
12 F2367103 CORD HOOK 1
13 G2217138 PEDAL LABEL(1) 1
14 G2217139 PEDAL LABEL(2) 1
15 G2217140 PEDAL LABEL(3) 1
16 G2217143 PEDAL LABEL(4) 1
17 G2217144 PEDAL LABEL(CTL) 1
18 G2217141 PEDAL LABEL(UP) 1
19 G2217142 PEDAL LABEL(DOWN) 1
20 G247751001 VGA KEYTOP S BLACK WITH LENS 20
21 G247751301 VGA KEYTOP S WITHOUT LENS 12
22 G2147806 STAY 1
23 G2477122 R-KNOB 15
24 G2567118 ESCUTCEON 1
25 G2227301 PEDAL ESCUTCHEON 7
26 G2187602 SWITCH PEDAL 7
27 G2177103 SUPPORT SPRING 7
28 G2357109 PEDAL FOOT 7
29 G2187904 PEDAL HOLDER 1
31 G2357111 CUSHION R 1
32 G1889117 PIN STAY 1
34 F5029405 LCD LMC-SSC2K16DLNY-H01 1
35 75D913M000 MAIN SHEET ASSY 1
36 75D913S000 SW SHEET ASSY 1
37 75D913S000 SW SHEET ASSY 1
38 75D913S000 SW SHEET ASSY 1
39 75D913S000 SW SHEET ASSY 1
40 75D913S000 SW SHEET ASSY 1
41 G2147874 BOLT HOLDER 2
42 75D9122S00 VR PEDAL UNIT INC. VR PLATE 1
NOTE: `VR PEDAL UNIT' includes the following parts.
30 ******** VR PEDAL 1
33 G2357112 VR PLATE 1
No. PART CODE PART NAME DESCRIPTION Q’TY
a H5029854 BOLT M3X12 HEX BUTTON FENI 6
b ******** NUT M9 (with ENCODER) 1
c ******** WASHER M9 (with ENCODER) 1
d ******** NUT M9 (with POT.) 1
e ******** WASHER M9 (with POT.) 1
f H5039510 NUT M9X12X2 (with PHONE JACK) FENI 8
g H5039112 WASHER M9 (with PHONE JACK) 8
h H5029843 SCREW 2.3X8 BINDING TAPTITE P ZC 1
I H5019803 SCREW 3X8 BINDING P-TIGHT FECM 20
j H5019130 SCREW M3X6 PAN MACHINE W/SW+PW ZC 5
k H5029331 SCREW 3X8 BINDING S-TIGHT FEBZC 21
m H5029330 SCREW M3X8 BINDING TAPTITE P BZC 3
n H5019428 SCREW M3X6 PAN MACHINE W/SW+SMALL PW BZC 10
o H5039520 M9 NUT 15
p H5030008 HEX BOLT M6X85 BZC 1
q H5039122 PLAIN WASHER 6X13X1 BZC 2
r H5039515 NUT M6 U BZC 1
s H5019434 SCREW M2.6X8 BINDING TAPTITE P BZC 1

11
GT-8
WIRING DIAGRAM
fig.haisen.eps
WIRING DIAGRAM PARTS
LIST
SW1 BOARD
ASSY
SW2 BOARD ASSY
SW3 BOARD
ASSY
EXP BOARD
ASSY
MAIN SHEET ASSY
CN6 CN4 CN3 CN2 CN5
CN1
CN9 CN8 CN7 CN3
CN5
CN6
ENC BOARD
ASSY
CN4
CN1
CN2
RIBBON 7P
RIBBON 3P
WIRING 3P
LCD
WIRING 12P
WIRING 8PWIRING 13PWIRING 7P
8
4
3
2
1
5
6
7
NO PART CODE PART NAME DESCRIPTION Q'TY
1 G3467180 LCD WIRING 16P L=160MM 1
2 G3467176 WIRING 7P P=2MM L=115MM 1
3 F3467039 WIRING 13P P=2MM L=65MM 1
4 G3467178 WIRING 8P P=2MM L=65MM 1
5 F3467038 WIRING 12P P=2MM L=120MM 1
6 G3477156 RIBBON CABLE 7P P=2MM L=140MM 1
7 G3467175 WIRING 3P P=2MM L=115MM 1
8 G3477146 RIBBON CABLE 3P L=40X5X5 MM P=2MM 1

12
Dec.2004
PARTS LIST
fig.part1e
SAFETY PRECAUTIONS:
The parts marked have
safety-related characteristics. Use
only listed parts for replacement.
NOTE: The parts marked # are new. (initial parts)
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
The description "Q'TY" means a necessary number of the parts per one product.
CASING
G2357120 FOOT H=5 5
# 75D912E000 BOTTOM COVER 1
G2227301 PEDAL ESCUTCHEON 7
G2357109 PEDAL FOOT 7
G2187602 SWITCH PEDAL 7
# 75D912C000 TOP COVER 1
75D9122S00 VR PEDAL UNIT INC. VR PLATE 1
NOTE: `VR PEDAL UNIT' includes the following parts.
# ******** VR PEDAL 1
G2357112 VR PLATE 1
KNOB,BUTTON
01340412 P R-KNOB SF-A BLK/LCG 1
12499175 BUTTON JSPUE001A 1
F2477101 DR-KNOB 1
G2477122 R-KNOB 15
G247751001 VGA KEYTOP S BLACK WITH LENS 20
G247751301 VGA KEYTOP S WITHOUT LENS 12
SWITCH
03344723 TACT SWITCH SKQKAKD010 SW1,SW2,SW3,SW4,SW5,SW6,SW7 on SW 7
F3129306 SWITCH SKQKAB SW8,SW9,SW10,SW11,SW12,SW13,SW14,S
W15,SW16,SW17,SW18,SW19,SW20,SW21,
SW22,SW23,SW24,SW25,SW26,SW27,SW28
,SW29,SW30,SW31,SW32,SW33,SW34,SW3
5,SW36,SW37,SW38,SW39 on SW
32
F3129307 PUSH SWITCH SDKLA1-B SW1 on MAIN 1
JACK,EXT TERMINAL
13429825 MIDI CONNECTOR YKF51-5054 2PZ JK7 on MAIN 1
# F3449121 YKC21-3117 RCA (PIN) JACK JK9 on MAIN 1
13449155MF PHONE JACK (MONO) HTJ-064-12I JK1,JK3,JK4,JK5,JK6 on MAIN 5
13449150MF JACK (STEREO) HTJ-064-12D JK2,JK8,JK10 on MAIN 3
13449728 ADAPTOR JACK HEC0740-010010 JK11 on MAIN 1
DISPLAY UNIT
F5029405 LMC-SSC2K16DLNY-H01 LCD 1
F5029412 A-552SR BW 7SEG LED LED31 on SW 1
PWB ASSY
# 75D913M000 MAIN SHEET ASSY 1
# 75D913S000 SW SHEET ASSY 1
IC
F5199520 S-812C33AY-Z-G REGULATOR IC31 on MAIN 1
F5199108 NJM2374AM-TE1 IC(SWITCHING REGULATOR) IC32 on MAIN 1
# 03785378 UPD442012AGY-BB85X-MJH IC (SRAM) IC19 on MAIN 1
15289123 M51953AFP-600C IC (RESET) IC34 on MAIN 1
# F5199109 BA17805FP IC (REGULATOR) IC30 on MAIN 1
# 03785134 TLP172A IC (PHOTO RELAY) IC37 on MAIN 1
# F5229704 PC400T IC (PHOTO COUPLER) IC16 on MAIN 1
F5289102 NJM2100M 8P SOP IC (OP.AMP) IC2,IC8 on MAIN 2
# F5189105 TC75S51F IC (OP AMP) IC23 on MAIN 1
# F5289104 M5238FP IC (JFET OP AMP) IC1 on MAIN 1
# ******** BM29LV800BA-70PFTN-SFKE1 IC (FLASH MEMORY/BLANK) IC25 on MAIN 1
02231767 RA0A-101 (TC223C080AF-101) IC (DSP) IC21,IC20 on MAIN 2
03347056 LC32V4265CT-25-TLM-E IC (DRAM) IC24 on MAIN 1
# 03784256 CS8406-CZ ZR IC (DIF/TRANSMITTER) IC27 on MAIN 1

13
GT-8
# F5249101 HD74HC4051P IC (CMOS) IC4,IC6 2
# F5249134 TC74HC08AF IC (CMOS) IC26 on MAIN 1
# F5279720 TC74VHC138F IC (CMOS) IC13 on MAIN 1
# F5249128 TC74VHC574FT(EL) IC (CMOS) IC11,IC14 on MAIN 2
# F5249129 TC74VHCT574AF IC (CMOS) IC12,IC15 on MAIN 2
# F5279311 TC7SH04F IC (CMOS) IC28 on MAIN 1
# F5249135 TC7SH04FU IC (CMOS) IC35,IC39 on MAIN 2
# F5279315 TC7SH32FU IC (CMOS) IC33,IC36 on MAIN 2
# F5279307 TC7W04F IC (CMOS) IC18 on MAIN 1
# F5289106 M5216FP IC (BIPOLAR OP AMP) IC6 on MAIN 1
15189261 M5218AFP-600E IC (BIPOLAR OP AMP) IC7,IC5 on MAIN 2
02451434 AK4552VT IC (AD/DA) IC3,IC9 on MAIN 2
03342312 HD6412312SVF IC (16BIT CPU) IC22 on MAIN 1
02678945 BU2090 IC IC1,IC2,IC3,IC5 4
IC
TRANSISTOR
G3467176 7P P=2MM L=115MM WIRING CN9 on SW 1
F5309115 2SA1241-Y TRANSISTOR Q10 on MAIN 1
15309104 2SA1586-GR(TE85R) TRANSISTOR Q6,Q5 on MAIN 2
F5309602 2SB1182 TRANSISTOR Q12 on MAIN 1
15319107 2SC4116-GR(TE85R) TRANSISTOR Q8 on MAIN 1
# F5129405 2SC4738GR TRANSISTOR Q9 on MAIN 1
F5319602 2SD1758 TRANSISTOR Q11 on MAIN 1
F5329529 RN1441 TRANSISTOR Q1,Q2,Q3,Q4,Q7,Q13,Q14,Q15 on MAIN 8
DIODE
F5339318 RD13ESAB2 ZENER DIODE D12,D11 on MAIN 2
15019126 1SS133 T-77 SWITCHING DIODE D1,D2,D3,D4,D5,D6,D7,D8,D9,D10,D11,D1
2,D13,D14,D15,D16,D17,D18,D19,D20,D21,
D22,D23,D24,D25,D26,D27,D28,D29,D30,D
31,D32,D33,D34,D35,D36,D37,D38,D39 on
SW
39
1502928100 L-34HDSL LED (RED) LED1,LED2,LED3,LED4,LED5,LED6,LED7,
LED8
8
F5029117 L-312LRD LED LED10,LED11,LED12,LED13,LED14,LED15
,LED16,LED18,LED19,LED20,LED21,LED2
2,LED23,LED24,LED25,LED26,LED27,LED
28,LED29,LED30
20
F5019203 1N4004 DIODE D7,D8,D10,D13 on MAIN 4
15339119 1SS-352 DIODE D1,D2,D3,D4,D6,D14 on MAIN 6
15339120 1SS302 DIODE DA4,DA5 on MAIN 2
02783023 RB500V-40 DIODE D5 on MAIN 1
F5339137 SS14 VF=0.45V DIODE D9 on MAIN 1
RESISTOR
F5419707 CRN34101J RESISTOR ARRAY RA3,RA4,RA6,RA9,RA15,RA18 on MAIN 6
F5419705 CRN34103J RESISTOR ARRAY RA1,RA2,RA7,RA14,RA17,RA21,RA22,RA2
6 on MAIN
8
F5419706 CRN34104J RESISTOR ARRAY RA5,RA8 on MAIN 2
# F5399909 0.68 (1/2W) RL2010JR-070R68 RESISTOR R122 (1.00 ~ 1.99Lot),R120 (2.00Lot ~) 1
F5399127 1.2K J RESISTOR R43,R1 on MAIN 2
F5399912 1.8K (F-RANK) RESISTOR R125 on MAIN 1
# F5429395 10 (0805SIZE 1/10W) RESISTOR R118,R126,R129 on MAIN 3
F5399115 100 J RESISTOR R73,R86 on MAIN 2
# F5399916 100K (F-RANK) RESISTOR R5,R48 on MAIN 2
# F5399918 12K (F-RANK) RESISTOR R4,R8,R47,R55 on MAIN 4
F5399150 18K J RESISTOR R46,R3 on MAIN 2
F5399919 1M(F-RANK) RESISTOR R90 on MAIN 1
F5399917 22 (1/2W) RESISTOR R77 on MAIN 1
F5399111 22 J RESISTOR R79 on MAIN 1
F5399913 3K (F-RANK) RESISTOR R124 on MAIN 1
F5399133 4.7K J RESISTOR R78,R81,R95,R96,R100,R101,R102 on MAIN 7
F5399920 4.7M(F-RANK) RESISTOR R91 on MAIN 1
F5399119 470J RESISTOR R69,R115 on MAIN 1
F5399195 470K J RESISTOR R44,R94 on MAIN 2
F5399158 47K J RESISTOR R18,R21,R29,R32,R37,R38,R39,R114,R117 on
MAIN
9
F5399914 6.8KF RESISTOR R9,R58 on MAIN 2
F5399116 82K J RESISTOR R71 on MAIN 1
F5399166 82K J RESISTOR R27,R16 on MAIN 2
# F5399139 1.8K MTL.FLM RESISTOR R128 on MAIN 1
# F5399120 150 MTL.FLM RESISTOR R111 on MAIN 1
F5399129 1.5K J MTL.FILM RESISTOR R119,R127 on MAIN 2
F5399104 10 J MTL.FILM RESISTOR R10,R59,R93 on MAIN 3
F5399170 100K J MTL.FILM RESISTOR R24,R35,R63,R64,R85,R116 on MAIN 6
F5399140 10K J MTL.FILM RESISTOR R2,R6,R12,R14,R17,R20,R25,R28,R31,R36,R4
1,R42,R45,R49,R52,R53,R57,R66,R72,R76,R8
2,R83,R87,R88,R89,R134,R141,R142,R148,R1
49,R153,R154,R155,R156 on MAIN
34

14
Dec.2004
F5399128 1K J MTL.FILM RESISTOR R22,R23,R33,R34,R60,R61,R80,R84,R110,R1
21,R160,R161,R162 on MAIN
13
F5399200 1M J MTL.FILM RESISTOR R7 on MAIN 1
F5399130 2.2K J MTL.FILM RESISTOR R70,R123 on MAIN 2
F5399190 220K J MTL.FILM RESISTOR R50 on MAIN 1
F5399118 330 MTL.FILM RESISTOR R26,R40,R75 on MAIN 3
F5399107 75 MTL.FILM RESISTOR R113 on MAIN 1
F5429374 33K OHM F RANK (1%) CHIP RESISTOR (1608 TYPE) R56,R62 on MAIN 2
F5429375 47K OHM F RANK (1%) CHIP RESISTOR R54,R65 on MAIN 2
F3829254 47OHM(2W) CARBON RESISTOR R13,R15 on MAIN 2
# 13749787 390 (1/6W) CARBON RESISTER R1,R2,R3,R4,R5,R6,R7,R8,R10,R11,R12,R13,
R14,R15,R16,R18,R19,R20,R21,R22,R23,R24,
R25,R26,R27,R28,R29,R30
28
# 13749789 470 (1/6W) CARBON RESISTER R31,R32,R33,R34,R35,R36,R37,R38,R39,R40,
R41,R42,R43,R44 on SW
14
RESISTOR
POTENTIOMETER
F3279802 RD901-40-125F-B54-00D POTENTIOMETER NO CLICK 50KB VR3,VR4,VR5,VR6,VR7,VR8,VR9,VR11,VR
12,VR13,VR14,VR15,VR16 on SW
13
F3279803 RD901-40-125F-B54-11D POTENTIOMETER 11 CLICKS 50KB VR2,VR10 on SW 2
F3279782 RK11K1140(10K SPECIAL B-CURVE POTENTIOMETER VR1 on SW 1
# F3229161 RK09K12A0 (50KAX2) 9M/M ROTARY POT. VR1 on MAIN 1
CAPACITOR
F3587451 ERZVA7V330 VARISTOR CAPACITOR C157 on MAIN 1
# 13649101 1/50 NON POLAR CHEMICAL CAPACITOR C200, C201 on MAIN 2
02341489 ECPU1C474MA5 MYLAR CAPACITOR(SUBMICRON) C5 on MAIN 1
13519694 RPE132-901F104Z50 MLT.LAY.CERAMIC CAPACITOR C1,C2,C3,C4,C5,C7 on SW 6
F5359732 GRM39B102J50PT CHIP CAPACITOR (1608 TYPE) C21,C33,C55,C67,C130 on MAIN 5
F5359780 GRM39B103K50PT CHIP CAPACITOR (1608 TYPE) C1,C46,C134,C135,C187,C188 on MAIN 6
F5359373 GRM39CH271J50PT CHIP CAPACITOR (1608 TYPE) C197 on MAIN 1
F5359725 ECJ1VC1H151J 150P J CHIP CAPACITOR C32,C43,C161 on MAIN 3
# F3629275 0.33UF/50V CHEMICAL CAPACITOR C189 on MAIN 1
13629550KM 100/16V CHEMICAL CAPACITOR C17,C29,C41,C164,C165,C167,C169 on
MAIN
7
F3629680 47/16V CHEMICAL CAPACITOR C4,C18,C25,C26,C27,C36,C38,C39,C49,C51,
C53,C58,C146,C153 on MAIN
14
# F3639555 470/6.3 CHEMICAL CAPACITOR C45,C160 on MAIN 2
F535970601 10P CERAMIC CAPACITOR C3,C7,C23,C24,C34,C35,C48,C52,C54,C68,C
172 on MAIN
11
F5359707 15P CERAMIC CAPACITOR C125,C123 on MAIN 2
# F5359801 ECJ1VF1E104Z 0.1Z CERAMIC CAPACITOR C9,C10,C11,C13,C16,C19,C20,C22,C31,C57,
C61,C63,C66,C69,C70,C71,C72,C74,C75,C76
,C77,C79,C80,C83,C84,C85,C86,C87,C88,C8
9,C90,C91,C93,C94,C95,C96,C97,C98,C99,C
100,C101,C102,C103,C104,C105,C106,C107,
C108,C109,C110,C111,C112,C113,C114,C11
5,C116,C117,C120,C121,C122,C124,C126,C1
27,C128,C132,C133,C136,C138,C139,C140,C
143,C144,C145,C147,C150,C151,C154,C155,
C163,C168,C185,C186,C190,C191,C198 on
MAIN
85
13639195 2200/35 CAPACITOR (ELECTOLYTIC) C158 on MAIN 1
F3629678TS 10/16V CAPACITOR C12,C14,C15,C28,C37,C40,C44,C50,C59,C60
,C62,C64,C65,C81,C82,C92,C118,C119,C129,
C131,C137,C141,C142 on MAIN
23
F3639637 470UF/35V CAPACITOR C149,C162,C166 on MAIN 3
INDUCTOR,COIL,FILTER
F2449220 TSL1112SRA-471KR72 INDUCTOR L17 on MAIN 1
F5409102 N1608Z601T02 FERRITE-BEAD L10,L11 on MAIN 2
13529246 DSS310-91D223S-50ATL12-134 EMI FILTER FL1,FL2 on MAIN 2
12449386 SBT-0180W EMI FILTER L15 on MAIN 1
CRYSTAL,RESONATOR
00891801 MA-406 24.000MHZ TE24 CRYSTAL X2 on MAIN 1
02672401 SG-8002JC 67.7376MHZ PC CRYSTAL X1 on MAIN 1
ENCODER
01905467 EVE GC1 F20 24B ROTARY ENCODER EN1 on SW 1
CONNECTOR
F3439123 A2001WR2-3P CONNECTOR 3P CN5 on MAIN 1
F3439121 A2541WR2-2A16NP CONNECTOR 16P CN1 on MAIN 1
# F3439231 A2001WR2-12P CONNECTOR 12P CN2 on MAIN 1
# F3439232 A2001WR2-13P CONNECTOR 13P CN4 on MAIN 1
F3439179 A2001WR2-7P CONNECTOR 7P CN6 on MAIN 1

15
GT-8
F3439164 A2001WR2-8P CONNECTOR 8P CN3 on MAIN 1
CONNECTOR
WIRING, CABLE
# F3467038 WIRING 12P P=2MM L=120MM CN5 on SW 1
# F3467039 WIRING 13P P=2MM L=65MM CN8 on SW 1
G3467178 WIRING 8P P=2MM L=65MM CN7 on SW 1
G3477156 RIBBON CABLE 7P P=2MM L=140MM CN3,CN2 on SW 1
G3467175 WIRING 3P P=2MM L=115MM CN1 on SW 1
G3477146 RIBBON CABLE 3P L=40X5X5 MM P=2MM CN4,CN6 on SW 1
G3467180 LCD WIRING 16P L=160MM 1
G3467176 WIRING 7P P=2MM L=115MM CN9 on SW,CN6 on MAIN 1
TRANSFORMER
02563501 PT-10 (2280-T008) PULSE TRANS TR1 on MAIN 1
SCREWS
H5039515 NUT M6 U BZC 1
# H5019428 SCREW M3X6 PAN MACHINE W/SW+SMALL PW BZC 10
H5019130 SCREW M3X6 PAN MACHINE W/SW+PW ZC 5
H5029854 BOLT M3X12 HEX BUTTON FENI 6
H5039510 NUT M9X12X2 FENI for Phone Jack 8
# H5030008 HEX BOLT M6X85 BZC 1
# H5029843 SCREW 2.3X8 BINDING TAPTITE P ZC 1
# H5019434 SCREW M2.6X8 BINDING TAPTITE P BZC 1
H5029330 SCREW M3X8 BINDING TAPTITE P BZC 3
H5029331 SCREW 3X8 BINDING S-TIGHT FEBZC 21
H5019803 SCREW 3X8 BINDING P-TIGHT FECM 20
H5039122 PLAIN WASHER 6X13X1 BZC 2
40016523 INSULOK TIE 100M/M T-18R ((1000 PCS ORDERING PER)) 2
H5039520 M9 NUT for VR 15
H5039112 WASHER M9 for Phone Jack 8
PACKING
# G2607117 COLOR SLEEVE 1
# G2617305 OUTER PACKING CASE 0.5
# G2607116 PACKING CASE 1
G2237620 PAD L 1
G2237616 PAD R 1
MISCELLANEOUS
# F2569105 CR2032 220MAH/3V LITHIUM BATTERY 1
02567267 BATRY HOLDER BCR20H4 BT1 on MAIN 1
H2369431 LED SPACER 3-2 LED8 on SW 1
G2147118 AC JACK HOLDER on MAIN 1
# G2147874 BOLT HOLDER 2
F2367103 CORD HOOK 1
G2357111 CUSHION R 1
G2567119 DISPLAY COVER 1
G2567118 ESCUTCEON 1
G2237112 GUARD 1
G2237113 GUARD PLATE 1
G2257203 JACK COVER on MAIN 1
G2187904 PEDAL HOLDER 1
G2217138 PEDAL LABEL(1) 1
G2217139 PEDAL LABEL(2) 1
G2217140 PEDAL LABEL(3) 1
G2217143 PEDAL LABEL(4) 1
G2217144 PEDAL LABEL(CTL) 1
G2217142 PEDAL LABEL(DOWN) 1
G2217141 PEDAL LABEL(UP) 1
# G1889117 PIN STAY 1
# G2637107 RUBBER SW 1
G2567121 RUBBER SW ESCUTCHEON 1
H2369401 SPACER 3X6X10 LED1,LED2,LED3,LED4,LED5,LED6,LED7
on SW
7
G2147806 STAY 1
G2177103 SUPPORT SPRING 7
ACCESSORIES (Standard)
G2457142 AC ADAPTOR BRC-240AT 1
G245714101 AC ADAPTOR BRC-230T 1
G2457144 AC ADAPTOR BRC-120T 1
G2457143 AC ADAPTOR BRC-100T 1
00905234 EURO CONVERTER PLUG ECP01-5A (PLUG for 230V) 1

16
Dec.2004
# G6047001 OWNER’S MANUAL JAPANESE 1
# G6047002 OWNER’S MANUAL ENGLISH 1
# G6027107 PRESET PATCH LIST JAPANESE/ENGLISH 1
# G6047005 READ ME FIRST JAPANESE/ENGLISH 1
# G6027108 USER PATCH LIST JAPANESE/ENGLISH 1
40232389 WARRANTY CARD FOR BOSS JAPAN ONLY 1
ACCESSORIES (Standard)

17
GT-8
CHECKING THE VERSION
NUMBER
1. Simultaneously hold down the [OUTPUT SELECT], [TUNER] and
[MANUAL] buttons and turn on the power to the GT-8.
2. The version number and checksum appear in the lower row of the LCD
display.
fig.version
USERS DATA SAVE AND
LOAD
Transmitting and Receiving MIDI
Data
On the GT-8, you can use Exclusive messages to provide another GT-8 with
identical settings, and save effect settings on a MIDI sequencer or other device.
Transmitting data this way is called “Bulk Dump,” while receiving such data is
referred to as “Bulk Load.”
Transmitting Data to an External
MIDI Device (Bulk Dump)
The following types of data can be transmitted. You can transmit data by
specifying the range from the start to the end of transmission.
Making the Connections
When Saving to a MIDI Sequencer
Connect as shown in the figure below, and put the sequencer in the state where
it is ready to receive Exclusive messages.
fig.08-140
* For instructions on operating the sequencer, refer to the owner’s manual for the
sequencer you are using.
When Transmitting Data to Another GT-8
Connect as shown in the figure below, and match the Device ID for the
transmitting and receiving devices.
fig.08-150
Transmitting
fig.08-160
1. Press [SYSTEM] twice, then press PARAMETER [ ] [ ] so that
“MIDI: Bulk Dump” is displayed.
fig.08-170d
2. Press PARAMETER [ ] [ ] to move the cursor, and rotate the
PATCH/VALUE dial to select the start and end of the data to be
transmitted.
3. When the data to be sent has been determined, press [WRITE].
The data is transmitted.
fig.08-180d
When the transmission is completed, the screen prior to transmission
returns to the display.
4. Press [EXIT] to return to the Play screen.
Displayed Data Transmitted
System System Parameters, Harmonist scales, Auto
Riff phrases, and Preamp/Speaker,
Overdrive/Distortion, and Wah Custom Edit
parameter settings
#1-1-#35-4 Settings for Patch Number 1-1 through 35-4
Temp Settings for the patch the is currently called up
GT-8
Ver. *.** [****]
MIDI OUT
MIDI IN
MIDI OUT
MIDI IN
1
1,2
4 3

18
Dec.2004
Receiving Data from an External
MIDI Device (Bulk Load)
Making the Connections
When Receiving Data Saved on a MIDI
Sequencer
Connect as shown below. Set the GT-8’s Device ID to the same number that
was used when the data was transmitted to the MIDI sequencer.
fig.08-190
* For instructions on operating the sequencer, refer to the owner’s manual for the
sequencer you are using.
Receiving
fig.08-191
1. Press [SYSTEM] twice, then press PARAMETER [ ] [ ] so that
“MIDI: Bulk Load” is displayed.
fig.08-200d
2. Transmit the data from the external MIDI device.
The following appears in the display when the GT-8 receives the data.
fig.08-210d
The following appears in the display when the GT-8 finishes receiving
the data.
fig.08-220d
At this stage, even more data can be received.
3. Press [EXIT] to quit Bulk Load.
After you press [EXIT], “Checking...” appears in the display, indicating
that the GT-8 is checking the received data. When the check is completed,
the Play screen returns to the display.
FACTORY RESET
INSTRUCTIONS
Restoring the Factory Settings
(Factory Reset)
Restoring the GT-8 to the settings made at the factory is referred to as “Factory
Reset.”
Not only can you return all of the settings to the values in effect when the GT-8
was shipped from the factory, you can also specify the range of settings to be
reset.
fig.09-060
1. Turn off the power.
2. While holding down PREAMP/SPEAKER On/Off button and [TYPE
VARIATION], turn on the power.
The Factory Reset range setting screen appears in the display.
fig.09-070d
* To cancel Factory Reset, press [EXIT].
3. Press PARAMETER [ ] [ ] to move the cursor, and rotate the
PATCH/VALUE dial to specify the range of settings you want to restore
to factory settings.
4. If you want to proceed with the factory reset, press [ENTER].
The specified range of data will be returned, and return to the Play
screen.
MIDI IN
MIDI OUT
1,2
3
value Explanation
System
System parameters, Harmonist scales, Auto Riff phrases, and Preamp/
Speaker, Overdrive/Distortion, and Wah Custom Edit parameter settings
Quick
Content of the Settings Made with User Quick Setting
#1-1-#35-4
Settings for Patch Number 1-1 through 35-4
4
3123
The range of data you wish to factory reset

19
GT-8
SYSTEM SOFTWARE
UPDATING INSTRUCTIONS
Required Equipment
• Sequencer (MC-80 or other)
• MIDI cable
• Update disk (#17041564)
Cautionary Note
Do not turn off the power to the GT-8 during writing of the system software.
This will prevent the system from being written properly to the flash ROM,
and as a result, the GT-8 will not operate.
Cautionary Note
Carry out Factory Reset after completing the update.
Updating the System with SMFs
The GT-8 system is provide in Standard MIDI File (SMF) format. The disk
contains the following SMF data; transfer the files to the GT-8 in sequence,
starting from GT8_01.mid.
GT-8 System Ver.*.** SMF Disk:
GT8_01.mid GT8_02.mid GT8_03.mid GT8_04.mid GT8_05.mid GT8_06.mid
GT8_07.mid GT8_08.mid GT8_09.mid GT8_10.mid GT8_11.mid GT8_12.mid
GT8_13.mid GT8_14.mid GT8_15.mid GT8_16.mid
Update the GT-8 system using the following procedure.
1. Connect the sequencer’s MIDI OUT connector and the GT-8’s MIDI IN
connector with a MIDI cable.
2. Hold down the ASSIGN [CTL/EXP], [NAME], and [MANUAL] buttons
and turn on the power to the GT-8.
fig.2-01up
appears in the LCD display, indicating the GT-8 is in standby mode.
3. Transmit the SMF data in GT8_01.mid from the sequencer to the GT-8.
When MIDI signals are received by the GT-8, the write address and
checksum appear in the LCD display.
fig.3-01up
When reception of GT8_01.mid is completed,
fig.3-02up
appears in the GT-8’s LCD display. Subsequently, the following is displayed.
fig.3-03up
Transmit the SMF data in GT8_02.mid from the sequencer.
In the same manner, continue to play back the SMF data in the remaining
files until the data in GT8_16.mid is loaded.
4. After the GT-8 has received all of the SMF data, a checksum (4-digit
number) of the system software is run; confirm the checksum value.
fig.4-01up
TEST MODE
If the GT-8 contains any user data, be sure to back up the data to a sequencer
(MC-80 or other) before servicing (for instructions on holding user data, refer
to “Saving Data” and “Loading Data”).
Test Categories
1.DSP Check
2.Display
3.LCD Contrast
4.Switch
5.VR Check
6.EXP PEDAL
7.Battery
8.MIDI IN/OUT
9.AMP CTRL
10.OUTPUT D/A
11.EXT LOOP
12.INPUT A/D
13.DSP INT0
14.Noise(IN->OUT)
15.Noise(LOOP)
16.Calibrate EXP
17.Factory Load
Required Equipment
• Expression Pedal (Roland EV-5)
• MIDI cable
• Oscilloscope
• Audio instrument which has DIGITAL in and Analog out.
• Guitar amp (equipped with jacks for switching channels/channel-
switching jack)
• Oscillator
•2monitor amps
• Noise meter
• Blank plug
Entering Test Mode
Simultaneously hold down the [DELAY] and [REVERB] buttons and turn on
the power to the GT-8.
The version number and checksum appear in the lower row of the LCD
display.
fig.test
Press the PARAMETER [>] button to proceed to “1. DSP Check.”
FJ: Waiting SMF
[GT8_01.mid]
GT8_01.mid SUM
******** ****
Now Updating...
******** ****
FJ: Waiting SMF
[GT8_02.mid]
All Completed.
Sum=****
GT-8 Build***
Ver. *.** [****]

20
Dec.2004
Quitting Test Mode
Power off the unit.
1. DSP Check
Press [WRITE]; the DSP is checked, and the results of the check are displayed.
If an error has occurred, the type of error is indicated; if the DSP is operating
properly, “OK” is displayed.
If operating properly
fig.1-01test
If an error has occurred (NG: No Good)
fig.1-02test
Press the [EXIT] button, then press the PARAMETER [>] button to proceed to
“2. Display.”
2. Display
Press [WRITE]; all of the LCD segments light up, and all LED indicators and
seven-segment LEDs remain lit.
Press [EXIT] to proceed to “3. LCD Contrast.”
3. LCD Contrast
fig.3-01test
Rotate the [PATCH/VALUE dial] in the following procedure to confirm the
corresponding changes in the LCD contrast.
1) Rotate the dial counterclockwise; the contrast decreases and the screen
darkens. Rotate the dial until the contrast reaches 0.
2) Rotate the dial clockwise; the contrast increases and the screen brightens.
Rotate the dial until the contrast reaches 15.
Press the [EXIT] button, then press the PARAMETER [>] button to proceed to
“4. Switch.”
4. Switch
Press the [WRITE] button; all of the LEDs light up, and the name of the button
being checked appears in the lower row of the LCD.
fig.4-01test
Press the switch corresponding to the indicated button.
“Wrong Switch” appears in the display if the incorrect switch is pressed.
For buttons with LEDs, confirm the following.
1) The LED is lit before the button is pressed.
2) The LED is off after the button is pressed.
Press the switches in the following sequence.
[1] Check of the effect select buttons and edit buttons:
[PREAMP] -> [PRE VARIATION] -> [PRE Ch A] -> [PRE Ch B] -> [PRE
SOLO] -> [PRE SPEAKER] -> [OD/DS] -> [OD/DS VARIATION] ->
[DELAY] -> [DELAY TAP] -> [CHORUS] -> [REVERB] -> [FX-2] -> [FX-1]
-> [WAH] -> [COMP] -> [EQ] -> [LOOP] -> [AMP CTL] -> [MASTER] ->
[ASSIGN CTL/EXP] -> [FX CHAIN] -> [EXIT] -> [PARAMETER (<)] ->
[PARAMETER (>)] -> [WRITE] -> [NAME] -> [ASSIGN VARIABLE] ->
[MANUAL] -> [TUNER/BYPASS] -> [SYSTEM] -> [OUTPUT SELECT]
[2] Check of the pedal switches and expression switches:
[BANK DOWN] -> [BANK UP] -> [BANK UP(EXP)] -> [CTL PEDAL] ->
[PEDAL 4] -> [PEDAL 3] -> [PEDAL 2] -> [PEDAL 1]
[3] Seven-Segment LEDs
Confirm that the segments in the seven-segment LEDs go off one at a time
each time [WAH] is pressed.
All of the segments should be off after the [WAH] button is pressed 14
times.
Press the PARAMETER [>] button to proceed to “5. VR Check.”
5. VR Check
Confirm that all of the VRs are turned down to the MIN position.
Press the [WRITE] button; the name of the VR being checked appears in the
bottom row of the LCD. Rotate the indicated display.
fig.5-01test
[1] Clicking VRs
[PRE TYPE] -> [OD/DS TYPE]
Rotate the knob from MIN to MAX and back to MIN, and confirm that the
value indicated in the seven-segment LEDs matches the corresponds notch
position.
[2] Non-clicking VRs
[PATCH LEVEL] -> [PRE LEVEL] -> [PRE PRESENCE] -> [PRE TREBLE] ->
[PRE MIDDLE] -> [PRE BASS] -> [PRE GAIN] ->
[OD/DS DRIVE] -> [OD/DS LEVEL] -> [DELAY FEEDBACK] -> [DELAY
LEVEL] -> [CHORUS LEVEL] -> [REVERB LEVEL]
Rotate the knob from MIN to MAX, and confirm that the segments in the
seven-segment LEDs light in sequence from the bottom in correspondence
with the change in knob position. After all have been checked, “OK”
appears in the display.
Press the PARAMETER [>] button to proceed to “6. EXP PEDAL.”
6. EXP PEDAL
Confirm the changes in the GT-8’s EXP pedal as an expression pedal connected
to the [SUB EXP PEDAL/SUB CTL 1,2] jack. Connect an EV-5 to the [SUB EXP
PEDAL/SUB CTL 1,2] jack.
Press the [WRITE] button. The display changes to the following.
fig.6-01test
Press the GT-8 EXP pedal and confirm that content shown in the LCD changes
as described below.
1) When the pedal is position approximately midway:
fig.6-02test
2) When the pedal is pressed fully forward:
fig.6-03test
3) When the pedal is brought back fully:
fig.6-04test
If the pedal is functioning properly, the display changes to the following; use
the same procedures to check the EV-5.
fig.6-05test
Press the PARAMETER [>] button to proceed to “7. Battery.”
1.DSP Check
--- OK ! ---
1.DSP Check
PRAM:NG ERAM:
1.DSP Check
PRAM:-- ERAM:NG
--
3.LCD Contrast
Contrast=15
4.Switch
PREAMP
5.VR Check
PRE TYPE
6.EXP PEDAL
[---][---][---]
6.EXP PEDAL
[---][***][---]
6.EXP PEDAL
[---][***][***]
6.EXP PEDAL
[***][***][***]
6.SUB EXP PEDAL
[---][---][---]

21
GT-8
7. Battery
Press the [WRITE] button; the voltage of the memory backup battery is
displayed.
fig.7-01test
Error indications:
“*.*V Low”: When the battery voltage is 2.0-2.6 V.
“No Battery!!”: When there is no battery, or when the battery voltage is below
2.0 V.
If the above occurs, supply the unit with a new lithium battery.
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “8. MIDI IN/OUT.”
8. MIDI IN/OUT
fig.8-01test
Connect the MIDI IN and MIDI out connectors with a MIDI cable.
Press the [WRITE] button. If the two connectors are not connected by the MIDI
cable, “No Connect” appears in the bottom row of the LCD display. If the two
connectors are properly connected, “Verify OK!” is displayed.
Press the PARAMETER [>] button to proceed to “9. AMP CTRL.”
9. AMP CTRL
Connect the AMP CTRL jack and the channel switching jack on the guitar amp.
Press the [WRITE] button; AMP CTRL automatically switches on/off.
fig.9-01test
Confirm that the guitar amp channels are switched.
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “10. OUTPUT D/A.”
10. OUTPUT D/A
Set the oscilloscope are follows.
1.0 V/DIV, 0.5 ms/DIV
Press the [WRITE] button; a rectangular wave is output from the OUTPUT
jack, and Mute is switched on/off.
fig.10-01test
Set the OUTPUT VR to MAX.
Connect only the OUTPUT L(MONO) jack to the oscilloscope (Channel 1), and
confirm that the waveform alternately changes as shown below.
Do not connect anything to OUTPUT R.
f
i
g
.
0
0
1
.
e
p
s
f
i
g
.
0
0
2
.
eps
Connect only the OUTPUT R jack to the oscilloscope (Channel 2), and confirm
that the waveform alternately changes as shown below.
f
i
g
.
0
0
3
.
e
p
s
f
i
g
.
0
0
2
.
eps
Connect the oscilloscope (Channel 1 and 2) to the PHONES jack, and use the
same procedure to confirm the waveform output.
Connect the oscilloscope (Channel 1 and 2) to the digital to analog converter,
and use the same procedure to confirm the waveform output.
Connect the oscilloscope (Channel 1) to the SEND jack, and confirm that the
waveform alternately changes as shown below.
f
i
g
.
0
0
4
.
e
p
s
f
i
g
.
0
0
2
.
eps
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “11. EXT LOOP.”
11. EXT LOOP
Connect the OUTPUT L/R jacks to the oscilloscope (Channel 1 and 2).
Press the [WRITE] button.
fig.11-01test
Confirm that the following type of waveform is output.
fig.005.eps
Insert the blank plug in the RETURN jack, and confirm that there is no
waveform.
After confirming this, remove the blank plug from the RETURN jack.
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “12. INPUT A/D.”
7.Battery
3.1V
8.MIDI IN/OUT
9.AMP CTRL
CTRL Off
9.AMP CTRL
CTRL On
<-->
10.OUTPUT D/A
Mute Off/-
10.OUTPUT D/A
Mute ---/On
<-->
<-->
<-->
<-->
11.EXT LOOP
[DSP>EXT>OUT]

22
Dec.2004
12. INPUT A/D
Input a rectangular wave, and observe the output waveform with the
oscilloscope.
INPUT: Rectangular wave, 400 Hz, 40 mVp-p
Press the [WRITE] button.
fig.12-01test
Confirm that the following type of waveform is output.
fig.006.eps
Rotate the OUTPUT VR from MAX to MIN and to MAX again, and confirm
that the amplitude of the waveform changes smoothly as the knob is turned.
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “13. DSP INT0.”
13. DSP INT0
Press the [WRITE] button; the DSP’s internal oscillator-generated pitch
interrupt signal is checked.
If an error occurs, the type of error is indicated in the display, and if operation
is normal, “OK!” is displayed.
If OK:
fig.13-01test
If an error occurs:
fig.13-02test
Press the PARAMETER [>] button to proceed to “14. Noise(IN->OUT).”
14. Noise(IN->OUT)
INPUT -> A/D -> DSP -> D/A -> OUTPUT
(Connect noise meter and observe)
Note: Check with both L(MONO) and R jacks.
When the OUTPUT jacks are used individually, the left and right channel
signals are mixed internally, so be sure to insert a blank plug in the R channel
output when measuring the L(MONO) channel; when checking the R channel,
insert the blank plug in the L(MONO) channel jack.
Press the [WRITE] button.
fig.14-01test
OUTPUT Level:MAX
Confirm that the residual noise is no more than -86.0 dB (JIS-A).
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “15. Noise(LOOP).”
15. Noise(LOOP)
INPUT -> A/D -> DSP -> D/A -> SEND -> RETURN -> A/D -> DSP -> D/A -
> OUTPUT
(Connect noise meter and observe)
Note: Check with both L(MONO) and R jacks.
When the OUTPUT jacks are used individually, the left and right channel
signals are mixed internally, so be sure to insert a blank plug in the R channel
output when measuring the L(MONO) channel; when checking the R channel,
insert the blank plug in the L(MONO) channel jack.
Press the [WRITE] button.
fig.15-01test
OUTPUT Level:MAX
Confirm that the residual noise is no more than -84.0 dB (JIS-A).
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to “16. Calibrate EXP.”
16. Calibrate EXP
Set the EXP pedal minimum and maximum values and the EXP pedal switch
threshold.
Press the [WRITE] button.
fig.16-01test
Bring the EXP pedal back completely, release, and press the [WRITE] button.
When set, “OK!” appears in the display, which subsequently shows the
following.
If operating properly:
fig.16-02test
If an error occurs:
fig.16-03test
Press the EXP pedal fully forward, release, and press the [WRITE] button.
When set, “OK!” appears in the display, which subsequently shows the
following.
fig.16-04test
Rotate the [PATCH/VALUE] dial to “6” and press the [WRITE] button.
When set, “OK!” appears in the display.
This completes Test mode.
Press the PARAMETER [>] button to proceed to “17. Factory Load.”
Press the [EXIT] button to quit Test mode.
12.INPUT A/D
[IN----->OUT]
13.DSP INT0
--- OK ! ---
13.DSP INT0
---ERROR!---
14.Noise(IN>OUT)
[IN----->OUT]
15.Noise(LOOP)
[RETURN->OUT]
16.Calibrate EXP
Set Pedal to MIN
16.Calibrate EXP
press [WRITE]
<-->
16.Calibrate EXP
Set Pedal to MAX
16.Calibrate EXP
press [WRITE]
<-->
16.Calibrate EXP
- Area Over ! -
16.Calibrate EXP
Threshold: 6